Biomimetic and Bioinspired Membranes: Preparation

Progress in Polymer Science 39 (2014) 1668–1720

Contents lists available at ScienceDirect

Progress in Polymer Science

j ournal homepage: www.elsevier.com/locate/ppolysci

Biomimetic and bioinspired membranes: Preparation

and application

a,b,1 a,b,1 a,b,∗ a,b

Jing Zhao , Xueting Zhao , Zhongyi Jiang , Zhen Li ,

a,b a,b a,b a,b

Xiaochen Fan , Junao Zhu , Hong Wu , Yanlei Su ,

a,b a,b b,c

Dong Yang , Fusheng Pan , Jiafu Shi

Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology,

Tianjin University, Tianjin 300072, China

Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China

School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China

a r t i c l e i n f o a b s t r a c t

Article history: By imitating the exceptional compositions, structures, formations and functions of bio-

Available online 20 June 2014

logical or natural materials, a myriad of biomimetic and bioinspired membranes have

been designed and prepared using cell membrane, lotus, mussel as representative proto-

types and biomineralization, bioadhesion, self-assembly as major tools. These membranes

have displayed fascinating properties and outstanding performances such as multi-

ple interactions, hierarchical organizations, multiple selective transport mechanisms,

Abbreviations: 8CP, cyclic peptide with the sequence of [d-Ala-l-Lys]4; AAO, anodic aluminum oxide; AIBN, azo-bis-isobutyrylnitrile; AQPs,

aquaporins; ATP, adenosine triphosphate; BCB, benzocyclobutene; BCP, block copolymer; BLM, bilayer lipid membrane; BMA, n-butyl methacrylate;

BPPO, poly(2,6-dimethyl-1,4-phenylene oxide); BSA, bovine serum albumin; C, cylindrical; CA, carbonic anhydrase; CBMA, 2-carboxy-N,N-dimethyl-

N-(2 -(methacryloyloxy)ethyl) ethanaminium; CNT, carbon nanotube; CP, carbopol; CS, chitosan; CVD, chemical vapor deposition; DA, dopamine;

DBSA, dodecylbenzenesulfonic acid; DCPD, dicyclopentadiene; DDT, d,l-dithiothreitol; DHN, 1,5-dihydroxynaphthalene; DMMSA, N,N-dimethyl-N-

methacryloxyethyl-N-(3-sulfopropyl) ammonium; DOPA, 3,4-dihydroxy-l-phenylalanine; EDC, N-(3-dimethylaminopropyl)-N -ethylcarbodiimide; G,

gyroid; GLPs, aquaglyceroporins; HA, hydroxyapatite; HABA, 2-(4 -hydroxybenzeneazo)benzoic acid; hb-PG, hyperbranched polyglycidol; HMTA,

hexamethylenetetramine; L, lamellar; LbL, layer-by-layer; MAPS, 3-(N-2-methacryloxyethyl-N,N-dimethyl) ammonatopropanesultone; MD, molec-

ular dynamics; Mefp-3, Mytilu edulis foot protein 3; MF, microﬁltration; MIP, major intrinsic protein; MMA, methyl methacrylate; MPC,

2-methacryloyloxyethylphosphorylcholine; MPDSAH, [3-(methacryloylamino) propyl]-dimethyl(3-sulfopropyl) ammonium hydroxide; MPEG, methoxyl

polyethylene glycol; MTPMS, 3-mercaptopropyltrimethoxysilane; NF, nanoﬁltration; NHS, N-hydroxysuccinimide; NIPS, non-solvent induced phase sep-

aration; NPS, poly(norbornenylethylstyrene); NR, nonrepetitive; ONB, ortho-nitrobenzyl; P2VP, poly(2-vinyl pyridine); P4VP, poly(4-vinylpyridine);

PAA, poly(acrylic acid); PAN, polyacrylonitrile; PANI, polyaniline; PB, polybutadiene; PBA, 1-pyrenebutyric acid; PC, phosphorylcholine; PCBM, [6,6]-

phenyl-C61-butyric acid methyl ester; PCL, polycaprolactone; PCOE, poly(cyclooctene); PCP, polycarbophil calcium; PDA, polydopamine; PDDA,

poly(diallyldimethylammonium chloride); PDMA, poly(dimethyl acrylamide); DMAEMA, N,N-dimethylamino-2-ethylmethacrylate; PDMS, polydimethyl-

siloxane; PDP, 3-pentadecyl phenol; PE, polyethylene; PEG, polyethylene glycol; PEGDA, poly(ethylene glycol) diacrylate; PEOM, poly(oxyethylene

methacrylate); PEMA, poly(ethylmethacrylate); PEMs, proton exchange membranes; PEO, poly(ethylene oxide); PES, polyethersulfone; PET, poly(ethylene

terephthalate); PFO, perﬂuorooctanoate; PI, polyisoprene; PLA, polylactide; PMB, poly(methyl butylene); PMCMA, poly(methyl methacrylate)-dibenzo-

18-crown-6-poly(methyl methacrylate); PMe(OE)xMA, poly(2-(2-methoxyethoxy)ethyl methacrylate); PMMA, poly(methyl methacrylate); PNIPAAm,

poly(N-isopropylacrylamide); P(Ns-S), poly(norborenylethylstyrene-s-styrene); POEGMA, poly[oligo(ethylene glycol) methyl ether methacrylate]; POSS,

polyhedral oligomeric silsesquioxane; PPO, poly(propylene oxide); PS, polystyrene; PSBMA, poly(sulfobetaine methacrylate); PSf, polysulfone; PSS,

poly(styrene sulfonate); PTFE, polytetraﬂuoroethylene; PVA, poly(vinyl alcohol); PVDF, poly(vinylidene ﬂuoride); PVP, poly(vinyl pyrrolidone); RO,

reverse osmosis; S, spherical; SBF, simulated body ﬂuid; SBMA, 2-(N-3-sulfopropyl-N,N-dimethylammonium)ethyl methacrylate; SEM, scanning electron

microscopy; SI-ATRP, surface-initiated atom-transfer radical polymerization; SI-RAFT, surface-initiated reversible addition-fragmentation chain transfer

polymerization; tBOS, tert-butoxystyrene; TEM, transmission electron microscopy; TNT, titania nanotube; UF, ultraﬁltration; UV, ultraviolet.

∗

Corresponding author at: Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology,

Tianjin University, Tianjin 300072, China. Tel.: +86 22 27406646; fax: +86 22 27406646.

E-mail address: [email protected] (Z. Jiang).

These authors contributed equally to this work.

http://dx.doi.org/10.1016/j.progpolymsci.2014.06.001

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1669

Keywords: superior stability/resistance and distinct adaptability. Meanwhile, these membranes have

Biomimetic made tremendous contributions in coping with energy and water stress, environment

Bioinspired

threats. Biomimetics focuses on the basic science by fundamentally exploring the prin-

Membrane

ciples of biological systems, while bioinspiration focuses on the applied engineering by

Biomineralization

technologically implementing the principles from biological systems. Biomimetics and

Bioadhesion

bioinspiration, as the complementary and interchangeable strategies for sustainable inno-

Self-assembly

vation and development of membrane technology, have great implications in exploring

membrane materials and intensifying membrane processes. This review will present a brief

overview on the prototypes, preparation, application as well as perspective of biomimetic

and bioinspired membranes.

Contents

1. Introduction ...... 1669

2. Natural prototypes for biomimetic and bioinspired membranes...... 1670

2.1. Cell membranes ...... 1670

2.1.1. Lipid bilayer ...... 1672

2.1.2. Membrane proteins ...... 1672

2.2. Biomineralization ...... 1674

2.3. Bioadhesion ...... 1674

2.4. Self-assembly ...... 1676

2.5. Self-cleaning ...... 1677

3. Fabrication of biomimetic and bioinspired membranes ...... 1679

3.1. Based on compositions of natural prototypes ...... 1679

3.1.1. Based on zwitterion and glycosyl ...... 1679

3.1.2. Challenges and shortcomings ...... 1681

3.2. Based on structures of natural prototypes ...... 1681

3.2.1. Based on biological channel...... 1681

3.2.2. Challenges and shortcomings ...... 1684

3.3. Based on formations of natural prototypes...... 1684

3.3.1. Based on biomineralization ...... 1684

3.3.2. Based on bioadhesion ...... 1687

3.3.3. Based on self-assembly ...... 1691

3.3.4. Challenges and shortcomings ...... 1699

3.4. Based on functions of natural prototypes ...... 1699

3.4.1. Based on self-cleaning ...... 1699

3.4.2. Challenges and shortcomings ...... 1702

4. Applications of biomimetic and bioinspired membranes...... 1702

4.1. Water treatment ...... 1702

4.2. Clean energy ...... 1706

4.2.1. Fuel cell...... 1706

4.2.2. Alcohol fuel...... 1707

4.2.3. Clean gasoline ...... 1708

4.3. Carbon capture ...... 1709

4.4. Health care ...... 1710

5. Conclusion and outlook ...... 1710

Acknowledgements ...... 1711

References ...... 1711

1. Introduction scale or operation mode can be adjusted expediently [2].

Nowadays, membrane technology has become one of the

Membrane technology has evolved as a green, perva- most important technologies in a broad range of applica-

sive technology over the past few decades owing to its tions, particularly in chemical and biological separation,

inherent advantages such as easy scale-up, mild condi- from industrial-scale separations, such as wastewater

tions, no or fewer additives and lower energy consumption treatment, seawater desalination and atmospheric gases

over conventional technologies such as distillation, adsorp- separation, to smaller-scale separations, such as biological

tion and extraction [1,2]. Most membrane processes are active components enrichment and puriﬁcation [3].

often performed without phase transition and at ambi- Learn from nature has become a popular philosophy in

ent conditions. In addition, membrane processes can scientiﬁc and technical communities. As we know, to imi-

provide favorable adaptability, which means the process tate something already proven to work well may increase

1670 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

the probability of successfully creating an analogous mate- Biomimetic and bioinspired membranes are those mem-

rial or process synthetically. Accordingly, biomimetics branes that are fabricated with natural or natural-like

and bioinspiration have grown as burgeoning research (inorganic, organic or hybrid) materials via biomimetic and

forefront in materials science, chemistry and chemical bioinspired approaches (biomineralization, bioadhesion,

engineering, of course, the afﬁliated membranes and self-assembly, etc.) to tailor speciﬁc properties (sophis-

membrane processes. The term biomimetics, which was ticated structures, hierarchical organizations, controlled

introduced in the 1960s, refers to the study of the struc- selectivity, antifouling or self-cleaning properties, etc.).

tures and functions of biological systems as models for the Research on biomimetic and bioinspired membrane has

design of engineering solutions [4]. Biomimetics is primar- developed rapidly during the last decade, with enhanced

ily limited to copying or imitating natural solutions, which knowledge on mechanisms, models, and functions from

work but may not be the easiest or most ideal answers. the contributions of many scientiﬁc disciplines. Ideally,

While biomimetics plays an important part in exploratory biomimetic and bioinspired membranes and membrane

research, its technological implementation is somewhat should possess the following features:

restricted. The transition from basic science to applied

•

engineering is just where bioinspiration takes over [5]. Membrane fabrication is often conducted through

Bioinspiration extracts fundamental ideas and principles self-assembly under mild conditions close to natural

from biological systems but without apparent resemblance environment, such as atmospheric pressure, room tem-

to the biological prototypes, quite often, the end use of perature, and aqueous environment.

•

bioinspiration differs from that of the original biological Membrane materials are usually common materials

prototypes. In this way, bioinspiration establishes a bridge with excellent hydrodynamic, mechanical, wetting, and

between basic science and applied engineering [5]. adhesive properties, primarily composed of the lightest

For either biomimetics or bioinspiration, biological elements – the ﬁrst two rows of the periodic table.

•

materials are always the exceptional prototypes. As is well Membrane structures are of hierarchical organization,

known, biological materials are organized in a hierarchi- spanning from molecular scale to nanoscale, microscale,

cal manner, with an intricate architecture that ultimately and macroscale, and bearing controlled conﬁguration,

makes up a number of different functional elements. mutable surface as well as robust interface.

•

The properties of the materials, which are arisen from a Membrane properties are often highly dependent on

complex interplay of physical and chemical interactions, the content and state of water in the structure, and

provide multifunctionalities of commercial potential [6]. membrane processes can be intensiﬁed by rationally

Particularly, cell and cell membranes become one of the manipulating the multiple selectivity mechanism in a

most prominent prototypes for biomimetic and bioinspired facile way.

membrane research [7]. Generally speaking, cell mem-

brane compositions (phospholipids, liposomes, membrane Although there are still many severe challenges to con-

proteins, etc.), structures and functions are indeed a school front, biomimetic and bioinspired membranes may turn

for membrane scientists. The biological cell is ﬁlled with into the next-generation membranes, and biomimetics

many different types of pores and channels that control and bioinspiration may open novel and efﬁcient avenues

the exchange of ions and molecules between subcellu- to advanced membrane technology. In this paper, an

lar compartments. These pores and channels are of vital overview is present from new conceptual perspectives

importance to cellular function. Examples include: ion for the current research and development of biomimetic

channels at the cell surface that regulate the ﬂow of ions; and bioinspired membranes with emphasis on natural

the nuclear pore complex that controls the transport of prototypes, membrane fabrication and structure manipu-

mRNA and proteins across the nuclear envelope of eukary- lation, and applications in water treatment, clean energy

otic cells [6]. Other biological materials with multiscale and carbon capture. The selected state-of-the-art examples

bio-structures, sophisticated bio-process control, and inge- shown in Fig. 1 illustrate the great diversity of biomimetic

nious bio-functions, such as teeth and bones, plant leaves, and bioinspired membranes based on imitation of com-

seashells, also brings wealthy inspirations for the research positions (zwitterion and glycosyl), structures (biological

and development of membranes and membrane processes. channel), formations (biomineralization, bioadhesion, self-

Synthetic membranes that mimic diverse structures, mate- assembly) and functions (self-cleaning) of the natural

rials, formations and functions found in biological systems prototypes. It should be noted that, the references provided

will greatly increase our chances of achieving membranes are by no means exhaustive, but serve as a starting point

that efﬁciently work within all energy and environmental for more detailed studies.

application realms. Furthermore, the design and fabrica-

tion of bioinspired membranes allow for incorporating the 2. Natural prototypes for biomimetic and

novel properties which does not exist in the biological bioinspired membranes

prototypes. Thus, it is probable to engineer bioinspired

membranes with performance superior to that of their bio- 2.1. Cell membranes

logical prototypes.

There are exciting and tremendous opportunities Among all the natural prototypes, cell membranes

to introduce both biomimetic and bioinspired con- are always the most important due to their incompa-

cepts, principles, models, designs into the research and rable abilities in mass transfer, energy transformation

development of membranes and membrane process. and signal transduction. Cell membranes are the frontier

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1671

Fig. 1. Overview of biomimetic and bioinspired membranes prepared by the imitation of materials, structures, formations and functions of natural

prototypes.

that separates the cell interior from the outside envi- membranes. According to the current knowledge, the

ronment, and play a crucial role in almost all cellular delicate structures and potent function of cell mem-

phenomena. Each cell consists of ∼63,000 ␮m membranes are mostly based on the ﬂuid lipid bilayer and

brane area and a human body with 10 cells means its embedded proteins (Fig. 2). Cell membranes are

7 2

a total of 10 m of membrane area [8]. Scientists are constructed with amphipathic lipids (phospholipids, gly-

always amazed by the high degree of sophistication, colipids, cholesterols and cholesterol esters), membrane

miniaturization and multi-functionalization found in cell proteins (integral proteins, lipid anchored proteins and

Fig. 2. Exuberant version of the ﬂuid mosaic model with different lipid species shown in different colors.

1672 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

peripheral proteins), and carbohydrates (polysaccharide forms a hydrophilic water gate responsible for the selec-

and oligosaccharides). tivity of AQP1: the oxygen atom of the water molecule

here will form hydrogen bonds with these amide groups

2.1.1. Lipid bilayer by changing the hydrogen-bonding partner from adjacent

The formation of cell membranes is a self-assembly pro- water molecules (Fig. 3b); the arrangement of the molecu-

cess driven by the amphipathic nature of phospholipid lar orbital for water results in the ﬁnely tuned water dipole

molecules. The nonpolar groups of phospholipids are inte- rotation (Fig. 3c). In addition, the diameter of the narrowest

grated into planar bilayers driven by hydrophobic effect. point is about 0.28 nm, which also forms a steric hindrance

In a planar lipid bilayer, the nonpolar groups are largely for other molecules. Collectively, the hydrophobic channel

buried in the hydrophobic interior of the bilayer, and the wall, hydrophilic nodes, and the narrow size of constric-

polar head regions are oriented to the external aqueous tion region confer the rapid and speciﬁc transport of water

phase [10,11]. The lipid bilayer is normally highly ﬂui- molecules [17].

dic with assemblies of lipids and amphiphilic proteins Ion channels are a series of pore-forming proteins for

(or lipoproteins) in the lipid matrix. Moreover, a number controlling the voltage gradient across cell membrane of

of biological processes occurring at cell membrane level living cells. Selective ion conduction and gating are two

are induced by interactions of the membrane lipids with key features of ion channels. Selective ion conduction reg-

exogenous peptides and proteins [12]. Zwitterionic phos- ulates the channel’s performance to select a certain ionic

phatidylcholine, as the major phospholipid located on the species among those present in the cellular environment

exterior surface, displays excellent nonthrombogenic and and catalyze them rapid ﬂow through [23]. Gating process

non-fouling features [12,13]. Such dynamic assembly of cell regulates the activity of ion channels by turning on or off.

membranes provides exceptional and precious examples Potassium (K ) channels, for example, have a selective ﬁl-

for rational design of antifouling membranes. ter near the extracellular side of the pore and a gate near

the intracellular side (Fig. 4) [24,25]. When K ion enters

2.1.2. Membrane proteins the selective ﬁlter, it dehydrates completely. The prodi-

Cell membranes exhibit outstanding permselectivity gious selectivity in K channels is due to the main chain

that promote certain substances permeating cell mem- atoms with a stack of customized polar oxygen cages that

branes. There are three means through which water and afford numerous closely spaced sites of suitable dimen-

other small molecules cross into or out of cells, known sions for precisely coordinating a dehydrated K ion. The

as simple diffusion, facilitated diffusion and active trans- protein packing around of the selective ﬁlter stretches out-

port. Small molecules, like water, oxygen, carbon dioxide, ward radially to hold the pore open at its proper diameter

ethanol and urea, can readily cross cell membranes by via hydrogen bonding and extensive van der Waals interac-

simple diffusion due to their higher solubility in the tions [26]. The electrostatic inﬂuence of four helix dipoles

oily interior phase of lipid bilayers. These molecules pass also ensures the cation selectivity by producing a negative

either directly through the lipid bilayer or through pores electrostatic (cation attractive) potential near the entrance

created by certain integral membrane proteins. Other sub- to the narrow selectivity ﬁlter [24]. Amino-acid sequence

stances like ions or small organic molecules are transported conservation provides a common structural basis for gating

through cell membranes via facilitated diffusion or active of K channels and the gating stimulus can be derived from

transport with protein-mediated carriers [14]. All these both ligand binding and membrane electric ﬁeld [25]. These

+ +

processes play a crucial role in regulating the movement delicate structures of the K channels insure that K ion can

of solutes and water. diffuse from one site to the next within only a very small

One important family of integral membrane protein is distance, and further prevent the accommodation of other

the major intrinsic protein (MIP) family. MIPs are mainly ions, that is, rapid conduction in the setting of high selectiv-

classiﬁed into aquaporins (AQPs) that are only permeable ity. Ion transport in nature also occurs via ion pumps. Ion

to water, and aquaglyceroporins (GLPs) that facilitate pas- pumps are large protein complexes with a central chan-

sive diffusion of small solutes such as glycerol or urea nel portion spanning in cell membrane [27]. Unlike ion

[15,16]. Among them, water channels have received the channels simply enabling the downhill movement of ions

most intensive research for their unique transport mecha- (passive diffusion), ion pumps are active transporters that

nism. Many types of water channels have been found [17]. fulﬁll different functions. The pumps transport ions against

For example, AQP1 water channels allow water to move their electrochemical gradient by coupling the “uphill”

freely and bidirectionally across cell membrane by osmo- transport process to an energy source, such as adenosine

sis, but not other small organic, inorganic molecules, ions or triphosphate (ATP) hydrolysis or the “downhill” movement

even protons [17–19]. The rate of water transport through of another ion or substrate molecule [28].

AQP1 (3 × 10 water molecules per subunit per second) is A cell membrane is one of most exquisite designs in

considerably faster than that in other described channels nature, that has cherished an inspiration source for fab-

[20]. The crystallographic and dynamic structures of AQP1 rication of artiﬁcial/synthetic membranes with designed

facilitate rapid water transport. It has been revealed that components, tailored structures, specialized functions and

the selective ﬁlter in AQP1 is rather hydrophobic, punc- targeted performance for diverse application ﬁelds. Par-

tuated by hydrophilic nodes. The channel is formed by ticularly, the sophisticated components and structures of

6 completely spanning ␣-helices and the junction of two lipids, membrane proteins, and multi-subunit assemblies

shorter helices [21]. This junction is held together by inter- in cell membranes offer abundant solutions in design-

actions between Asn 76 and Asn 192 amino acids and ing artiﬁcial membranes with speciﬁc components and

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1673

Fig. 3. Schematic representations of the water molecules transport in AQP1. (a) Diagram illustrating how partial charges from the helix dipoles restrict the

orientation of the water molecules passing through the constriction of the pore. (b and c) Diagram illustrating hydrogen bonding of a water molecule with

Asn 76 and/or Asn 192.

Fig. 4. Approximate cross-section of K channels with wide-open intracellular vestibule and pore helix dipoles (left) and the high resolution structure for

a closed channel.

1674 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

Fig. 5. A simplistic view of the roles the inorganic and organic constituents played in biomineral formation process.

hierarchical structures through different physically and formation process [31]. Generally, inorganic mineral reac-

chemically controlled mechanisms. The excellent and tants and insoluble organic matrix are essential factors

unique features of cell membranes, such as antifouling, because the former is the sources of inorganic elements,

self-healing, controllable permeability, may have great while the latter provides substrate, compartment and acts

implications in exploitation of artiﬁcial membranes. as an inducer and template for the deposition of the min-

eral. In addition, the crystallographic control could be

regulated by incorporation of inorganic impurities and/or

2.2. Biomineralization

organic additives. Although it is impossible to understand

the authentic mechanisms that lead to the formation of

Biomineralization demonstrates how organisms make

each speciﬁc biomineral, there are still some common

hard stuffs under mild and green conditions. Biomin-

strategies for mineralization manipulation which encom-

eralization refers to the mineral-formation process in

pass chemical control, spatial control, structural control,

organisms, during which inorganic elements aggregate on

morphological control, and constructional control [30,36].

speciﬁc organics from the surrounding and form miner-

Compared with artiﬁcially synthesized materials, the

als under the inducing and modulating of organics. The

materials formed through biomineralization generally

most signiﬁcant feature of biomineralization is that the

have more complex structure with hierarchical organiza-

biomolecules such as protein, polysaccharide and peptide

tion, and consequent superior physicochemical properties

secreted by cells dictate the formation of minerals with

for the molecular-level control of organisms over the

speciﬁc shape, size, orientation and structure through the

nano- and microstructure of the biominerals [29,37,38].

ordered assemblies of biomolecules and the interaction

For instance, the ordered brick-and-mortar arrangement

between organic and inorganic phases [29].

of proteins and CaCO3 tablets in seashell nacre com-

Biomineral was a name invoked by mineralogist in

bines the elasticity of proteins and the strength of CaCO3,

the 20th century when they studied minerals formed by

endowing the seashell nacre with hardness, strength and

living organisms. Living organisms are famous for exploi-

toughness superior to many man-made ceramics [39].

ting the material properties of minerals when producing a

Moreover, the physiological environment in living orga-

broad range of organic–inorganic hybrid materials for spe-

nisms determines that the biominerals can be synthesized

ciﬁc applications [30]. There widely exist biomineralization

under mild and environmental-friendly conditions (nearly

phenomena in each of ﬁve major organism groups in nature

neutral pH, atmospheric pressure, room temperature, and

[30]. About 70 kinds of biominerals have been identiﬁed

aqueous environment) [40]. In short, the biomineralization

forming in vivo to date [31], such as the silica in diatoms

process combines fascinating morphology with superior

[32], the calcium carbonate in the skeletons of the inverte-

properties and environmental-friendly conditions, that are

brate [33], the calcium phosphate in the bones and teeth of

all attractive features for material synthesis [37]. Conse-

the vertebrate [34], as well as the iron oxide and iron sulﬁde

quently, mimicking the biomineralization process has been

in the magnetotactic bacteria [35]. Among them, calcium-

a promising and effective strategy for the design and syn-

based and silicon-based minerals are the most widely

thesis of advanced inorganic and organic–inorganic hybrid

existed, and calcium-based mineral almost constitutes half

materials via a green and low-energy input process [41].

of the biominerals [36]. Materials with same chemical com-

position may present diverse morphologies if they are

formed under different circumstances. For instance, the 2.3. Bioadhesion

calcium carbonate formed in the leaves of plants is amor-

phous, while it is calcite in the shell of mollusk [36]. Bioadhesion demonstrates how natural materials

Fig. 5 shows a simplistic view of the roles that the adhere to a broad variety of solid surfaces in rapid and

inorganic and organic constituents play in biomineral robust way. In nature, there exist abundant intriguing

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1675

Fig. 6. (a) A community of mussels afﬁxed to rocks. (b) Mussels adhering to glass. The picture shows their byssus adhesive system consisting of threads

and plaques. (c) An [Fe(DOPA)3] complex.

bioadhesion phenomena especially in marine organisms foot protein 3 (Mefp-3) and Mefp-5, which are rich in

such as mussels, sandcastle worms, barnacles, giant clams, 3,4-dihydroxy- -phenylalanine (DOPA) with the content

limpets, tube worms, star ﬁsh, sea cucumbers, and kelp of 21 mol% and 27 mol%, respectively [44,48,49]. As for

[42,43]. For instance, marine mussels can secrete adhe- sandcastle worms, nearly 10 mol% DOPA is detected in

sive proteins along the abundant threads fanning out from the polyanion protein Pc3B in cement [47,50]. DOPA plays

shells, and then form the outer coating of thread and the crucial roles in adhesive proteins: participating in the reac-

adhesive plaques terminating each thread [42]. The adhe- tions leading to the hardening of bulk adhesive proteins;

sive proteins can adhere to solid surfaces and harden in forming strong covalent and noncovalent interactions with

a short period of time to form a solidiﬁed layer in water substrates due to the chemically multi-functional property

so that the mussels can be attached on virtually all types of catechol groups on DOPA [44]. Moreover, metal ions

of substrates including the hulls of ships and rocks ﬁrmly in non-mineral form are found to be essential in various

even in the most wave-swept habitats [43–45]. Fig. 6b bioadhesive processes. Iron–DOPA complexes are formed

showed the attachment of mussels on glass with an adhe- in the byssus of mussel (Fig. 6c) and show at least two

sive system consisting of threads and plaques, which is functions [42]: improving the hardness and extensibility

called “byssus” or “beard”. Other representative examples of the threads simultaneously via the reversible formation

are the sandcastle worm (Phragmatopoma californica), and of iron–DOPA bonds; inducing the oxidation and the subse-

the related species of marine polychaetes, which can secret quent reactions of DOPA, and then achieving the formation

cement from the “building organ” on their thoraces to glue of outer coating of threads and adhesive plaques. Calcium

particles such as sand grains and shell fragments together, and magnesium are major metal ions in cement secreted

and then construct a tube-like shelter [43,46,47]. The glu- by sandcastle worm, which play a complex and multifunc-

ing process occurs rapidly and is applicable for a variety tional role in preserving the structure and stickiness of the

of solid materials in seawater environment [43]. As shown cement.

in Fig. 7, when portion of a worm’s tube is removed, and Compared with synthetic adhesives, bioadhesives

meanwhile building blocks such as glass beads are sup- possess a lot of advantages, such as the superior strength,

plied, the worm will perform the gluing process to repair durability, nontoxicity, universality, as well as the rapi-

its tube judiciously. der formation process, and milder formation condition

The adhesive systems mentioned above have a few sim- [42,43,48]. Moreover, all the bioadhesion processes in

ilarities in composition. It has been investigated that the living organisms occur in the presence of water [51],

mussels’ adhesive capacity may lie in the proteins found yet underwater adhesion is a pervasive problem for

near the plaque-substrate interface, including Mytilu edulis most man-made adhesives. Consequently, the bioadhesion

Fig. 7. Sandcastle glue. (a) A tube rebuilt on top of the natural tube with 0.5 mm glass beads in the laboratory. (b) Close-up of the rebuilt tube. (Arrows

indicate spots of glue holding beads together.)

1676 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

Fig. 8. High oligomeric assemblies from silk proteins.

phenomena and mechanisms have attracted enormous the well-known examples is the spider silk for its tremen-

attention in recent years. Many researchers have attempted dous strength and ﬂexibility [60]. Spiders can produce

to screen or synthesize analogs of bioadhesives by imitating several types of spider silks from amphiphilic silk proteins

the constitutions and properties of bioadhesives because (spidroins) with repetitive hydrophilic and hydrophobic

of the huge difficulty and cost to obtain purified natural amino acid stretches flanked by conserved nonrepeti-

bioadhesives [43,44,52]. For instance, dopamine (DA) has tive (NR) amino-terminal and carboxy-terminal regions

been widely utilized as adhesive due to its similar structure [61–63]. The assembly of charged N-terminal domain can

and properties with DOPA [52,53]. The burgeoning stud- be precisely controlled by pH, allowing the intrinsic pH

ies about bioadhesion mechanisms offer rich inspirations gradient of spider silk glands to regulate silk formation.

for exploring a variety of biomimetic adhesion strategies, The C-terminal domain, indifferent to pH, affects silk for-

which may have promising application prospects in fabri- mation by ordering assembly of repetitive segments into

cating composite membranes with robust interface [54]. ﬁbers [61,62]. The larger hydrophilic NR terminal regions

render these silk protein molecules surfactant-like with the

2.4. Self-assembly ability to form micelles (or hexagonal columns), followed

by larger globular structures which are elongated by the

Self-assembly demonstrates how organisms form a changes in their extensional ﬂow and shear forces, form-

broad variety of advanced structures with high level of ing the precursors of the subsequent spider silk ﬁber (Fig. 8)

precision and complexity. Self-assembly is the sponta- [64].

neous organization of molecules under thermodynamic Self-assembly, as a common property of extracellu-

equilibrium conditions into structurally well-deﬁned lar organic matrix macromolecules, is always facilitated

arrangements [55]. Nature is genius to design chemically by speciﬁc intermolecular interactions. The formation

complementary and structurally compatible constituents of natural inorganic–organic composites starts with the

for molecular self-assembly [56], such as peptide/proteins, assembly of the extracellular matrix followed by selec-

DNA/RNA, and polysaccharides. The ubiquity of self- tive transportation of inorganic ions to discrete organized

assembly phenomenon in nature at both microscopic and compartments, subsequent mineral nucleation, and ﬁnally

macroscopic scales describes the spontaneous association mineral growth delineated by the conﬁned cellular com-

of numerous individual entities into coherent organiza- partments [65,66]. For example, self-assembly for protein

tions and well-deﬁned structures via numerous speciﬁc scaffolds plays a role in the rich diversity of compos-

and nonspeciﬁc inter-/intramolecular interactions [56,57]. ite seashells [67]. During shell formation, the mineral

Cell membrane is a typical example of molecular phase forms within an assembled organic matrix composed

␤

self-assembly in nature (described in Section 2.1). The of polysaccharide -chitin, relatively hydrophobic silk

lipid bilayer structure can exhibit complex morphological proteins, and hydrophilic acidic glycoproteins rich in aspar-

changes by phospholipids assembly. For example, prim- tic acid, which determines mineralized shell structures

itive cells maintain the basic cellular functions, such as [66,68,69]. Shell nacre comprises an ordered multilayer

growth and division, with the assistance of lipid assem- structure of crystalline calcium carbonate platelets sepa-

bly [58]. The lipid bilayer also plays important role in the rated by porous organic layers (Fig. 9) [70]. The process

assembly and organization of amphiphilic transmembrane of assembly was certainly orchestrated by mantle cells.

proteins, which driven by hydrophobic (or hydrophilic) Mantle cells produce and release matrix components into

interactions [59]. the extracellular environment. Then these matrix compo-

Natural peptides and proteins can self-assemble into nents can ﬁnd their correct locations through spontaneous

highly ordered supramolecules because of their exquisite assembly. The last stage of assembly is the introduction

structures and evolutionarily ﬁne-tuned functions. One of of the silk-like protein gel to space ﬁlling to keep the

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1677

Fig. 9. (a) Photograph of the bright iridescence of nacre (scale bar, 5 mm). (b) Fractured surface scanning electron microscopy (SEM) image of a stack of

mineral tablets (scale bar, 2 ␮m). (c) Organic inter-crystalline, ﬁlm which allows for vertical crystal continuity between tablets (scale bar, 500 nm).

successive interlamellar sheets separated at uniform dis- nanoscale branch-like growths occurring on the epidermal

tances from each other [71]. Likewise, the natural pearl is cells (Fig. 10a and b) [76,77]. Hierarchical roughness built

also composed of CaCO3 interspersed between layers of by convex cell papillae and randomly oriented hydrophobic

an organic material, such as chitin and matrix proteins. wax tubules are vital for the maintenance of self-cleaning

Matrix proteins are in charge of the crystal phase, shape, properties (Fig. 10c) [78,79]. Contaminating particles on

size, nucleation and aggregation of CaCO3 crystals [72]. The lotus leaves can be picked up by the water droplets and

beautiful luster of natural pearl is also provided by the lay- removed with the droplets [80]. Different plant surfaces

ered structure of the materials. always appear very different surface structures as shown

Self-assembly has been proposed as an intelligent and in Fig. 11. The unique structures in two scales are beneﬁcial

bioinspired strategy for producing membranes with con- to trapping air, lowering surface energy, and forming the

trolled architecture and composition, and highlighted for self-cleaning surfaces [81]. The physical adhesion forces

incorporating a variety of building blocks into artiﬁ- between contaminating particles and the structured sur-

cial/synthetic membranes. faces can be largely reduced.

In nature, the self-cleaning is not restricted to plant sur-

faces. A great variety of self-cleaning surfaces have also

2.5. Self-cleaning

been found in insect wings, water strider legs, insect eyes,

ﬁsh scales, shark skin, gecko feet, spider silks, bird feathers,

Self-cleaning demonstrates how organism surfaces

etc. [75,84].

exhibit low adhesion for a broad variety of foulants in

Beautiful examples are butterﬂy wings. For the Mor-

ﬂuid ﬂow. The attributes of biological surfaces from a

pho butterﬂy wings, the speciﬁc multiscale and highly

complex interplay between chemistry and surface mor-

ordered photonic structures enhance superhydrophobicity

phology often play a pivotal role in determining the

and self-cleaning features (Fig. 12) [85,86]. The directional

wettability of biological materials. Superhydrophobic non-

easy-cleaning property of the Morpho butterﬂy wings is

wetting capability is a fundamental property of typical

attributed to the direction-dependent arrangement of ﬂex-

self-cleaning biological surfaces. In plants, the self-cleaning

ible nano-tips on the lamella-stacked nano-stripes and

phenomenon is widely known as the “Lotus effect”. Water

micro-scales overlapped on the wings [87].

drops on lotus leaves bead up with a high contact angle

Gecko feet can keep self-cleaning while walking with

and roll off, collecting dirt along the way, in a mechanism

sticky toes. The self-cleaning ability could be attributed

known as self-cleaning [73].

to the microstructure (setae on overlapping lamellar pads

Micro- and nano-structures of plant surfaces take

in uniform arrays) and nanostructure (single seta with

an important part in self-cleaning property. Some plant

branched structure terminating in hundreds of spatular

surfaces are superhydrophobic and self-cleaning due to

tips). Non-adhered lamellar surfaces appear to be highly

the hierarchical roughness and hydrophobic epicuticular

non-wettable, and particles contacting the unloaded sur-

waxes. The lotus leaf is one of the best-known and typical

face should wash away easily in the presence of water.

biological objects owing to the combination of hydropho-

Moreover, gecko feet contaminated with microspheres

bic epicuticular wax and the micro/nanoscale hierarchical

could also recover their ability to cling within only a few

architectures on the surface [74,75]. The ﬁrst structure con-

steps on dry clean glass. Self-cleaning is derived from

sists of micro-level mound-like protrusions with papillose

the energetic disequilibrium between the adhesive forces

epidermal cells and the secondary structure consists of

1678 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

Fig. 10. (a) Large-area SEM image of the lotus leaf surface. Every epidermal cell forms a papilla and has a dense layer of epicuticular waxes superimposed

on it. (b) Enlarged view of a single papilla from panel [76]. (c) SEM image of 3D epicuticular wax tubules on lotus leaf surfaces, which create nanostructures

[79].

respectively.

Fig. 11. SEM images of the surface of (a) hierarchically structured papillae arranged in quasi-one-dimensional order parallel to the leaf edge [82], (b)

periodic array of close-packed hexagons and strips on Chinese Kaﬁr lily petal [83], (c) periodic array of parallel lines and helices on sunﬂower petal [83],

and (d) unitary web of micro-ﬁbers on ramee rear face [81].

Fig. 12. Hierarchical micro- and nanostructures on the surface of the Morpho butterﬂy wings. (a) Secondary electron image of overlapping scales possess

an overall rectangular shape with pointed tips. (b) Secondary electron image of the porous architecture of the scale with parallel microscale ridges aligning

along the scale length and nanoscale ribs lying on each ridge.

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1679

Fig. 13. Surface structures of fish scales. (a) Optical image of the fish scales. (b) SEM image of fish scales.

attracting a dirt particle to the substrate and those attract- 3.1. Based on compositions of natural prototypes

ing the same particle to one or more spatula [88–90].

Apart from nature superhydrophobic surfaces in air, 3.1.1. Based on zwitterion and glycosyl

nature also create low adhesive surfaces in water environ- 3.1.1.1. Fabrication of membranes via surface zwitteri-

ments, such as the surface of ﬁsh composed of hydrophilic onization. Zwitterions involved a series of compounds

ﬂexible mucus and tough scales, acting as the inspiration to that consist of an equal number of positively and nega-

develop underwater self-cleaning surfaces. Sector-like carp tively charged groups, thus exhibiting apparently neutral

scales are covered by oriented micropapillae with nano- state. It is known that there exist biological zwitterionic

␮ ␮

structures with 100–300 m in length and 30–40 m in phospholipids located at the outside lipid layer of cell

width, arrange in the radial direction (Fig. 13) [91]. When membrane to prevent the adhesion of exterior matters

the ﬁsh scales come in contact with the oil droplets in in biological ﬂuids and improve biocompatibility with

water, the ﬁne-scale hierarchical structures can trapped the surrounding tissues [13]. In case of biomimetic and

water molecules and form an oil/water/solid interface with bioinspired membranes, diverse zwitterionic compounds

superoleophobic property. Another example of underwa- have been utilized for membrane surface zwitterioniza-

ter self-cleaning surface is shark skin, covered by very small tion. Considering the superior fouling resistant nature

individual tooth-like dermal denticles ribbed with longitu- of zwitterionic head group in cell membranes, the

dinal grooves [92]. These grooved scales aligned parallel to objective of surface zwitterionization is to prevent the

the local ﬂow direction of the water could reduce the for- foulants from attaching onto the membrane surface. Since

mation of vortices over the smooth skin surface, improving the phospholipid coated antifouling membranes were

water movement efﬁciently [84]. reported by Reuben and coworkers [93], several typical

Collectively, the micro- or nano-structures and the zwitterionic moieties has been successfully introduced

chemical nature of biological surfaces are responsible for onto membrane surface, such as N-(3-sulfopropyl)-N-

repelling contaminant matters from their surfaces, and can (methacryloxyethyl)-N,N-dimethylammonium betaine

serve as an intriguing route to construct biomimetic and (SBMA), 3-(N-2-methacryloxyethyl-N,N-dimethyl)

bioinspired self-cleaning membrane surfaces. ammonatopropanesultone (MAPS), 2-carboxy-N,N-

dimethyl-N-(2 -(methacryloyloxy)ethyl) ethanaminium

(CBMA), [3-(methacryloylamino) propyl]-dimethyl(3-

3. Fabrication of biomimetic and bioinspired sulfopropyl) ammonium hydroxide (MPDSAH),

membranes 2-methacryloyloxyethyl phosphorylcholine (MPC), etc.

The strong hydration of the zwitterionic moieties would

Nature, that evolves commonly found materials with generate strong hydration layer on membrane surfaces via

desired functionality by highly sophisticated methods, electrostatic interactions, which endow high hydrophilic-

has been illuminated as a source of inspiration for the ity and good fouling resistant abilities to membranes

exploitation of advanced membrane materials. Given that [94].

biological compositions, structures, formations, and func- Grafting zwitterionic moieties onto/from membrane

tions always span multiple scales from molecular scale to surfaces offers an effective approach to realize sur-

nanoscale, microscale, or macroscale in a hierarchical and face zwitterionization by covalent bonding and has been

smart manner to ultimately make up a myriad of different received a great deal of attention. Various chemical

functional elements, the fascinating aspects of biomimetic reactions were employed to ﬁx zwitterionic moieties

and bioinspired approach has been particularly appealing on membrane surfaces after membrane formation. Graft

for the creation of novel synthetic membranes with excep- polymerization is a promising and attractive route of mem-

tional compositions, structures, formations and functions. brane surface modiﬁcation due to the broad diversity of

The brief introductions of the six types of biomimetic and monomer species. As one of the conventional approaches

bioinspired membranes in this review and the correspond- to graft functional polymer brushes from membrane sur-

ing natural prototypes are listed in Table 1. faces, high energy radiation-initiated graft polymerization

1680 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

Table 1

The brief introduction of natural prototypes and the corresponding biomimetic and bioinspired membranes.

Classiﬁcations Natural prototypes Biomimetic and bioinspired membranes

Based on composition Zwitterion and glycosyl: the functional groups on the Antifouling membranes with functionalized surfaces

outside of cell membrane which render antifouling resembling the composition of cell membrane through

properties surface zwitterionization and glycosylation

Based on structure Biological channel: the transmembrane proteins or protein Nanoporous membranes with ordered transport

assemblies which provide the fastest and speciﬁc transport channels for ions and small molecules through

channels for ions and small molecules via passive transport incorporating biological channel proteins and/or

artiﬁcial nanochannels

Based on formation Biomineralization: the formation process of biominerals in Organic–inorganic hybrid membranes with inorganic

organisms through precise hierarchical assembly of nanoparticles formed within polymeric matrix

nanoscale building blocks under regulation of through the in situ mineralization reaction of inorganic

biomolecules precursors under the inducing and modulating of

organics

Bioadhesion: the high-strength conglutination of Composite membranes with high interfacial strength

organisms (especially marine organisms) onto solid between different layers or different moieties through

surfaces under mild condition and aqueous environment incorporating biomimetic adhesion strategy to form

through the combination of multiple interactions multiple interactions on interfaces

Self-assembly: the spontaneous organization of molecules Nanoporous membranes with ordered channels

under thermodynamic equilibrium conditions into through self-assembly of block copolymers;

structurally well-deﬁned arrangements based on nanoporous membranes with hydrophilic surface

numerous speciﬁc and nonspeciﬁc inter-/intramolecular through self-assembly and spontaneous segregation of

interactions amphiphilic copolymer (surface segregation)

Based on function Self-cleaning: the capacity of some biological surfaces to Self-cleaning membranes with superhydrophobic or

clear dirt away and keep themselves clean due to their superhydrophilic/oleophobicity surfaces through

superhydrophobic and non-wetting attributes incorporating low surface energy moieties or high

hydration energy moieties

has attracted considerable attention, by which radia- has been developed to grant the membranes high

tion grafted zwitterionic brushes can be achieved with hydrophilicity and ensure the overall charge neutrality.

simple control. With the help of plasma pretreatment Most recently, the use of click chemistry for surface

and UV-irradiated technique, surface zwitterionization has modiﬁcation provided a new route to membrane surface

been conducted using the graft polymerization of the zwitterionization, thanks to the mild reaction conditions,

zwitterionic monomer on the highly hydrophobic sur- good control, and high yield. The surface attachment of

face of poly(vinylidene ﬂuoride) (PVDF) microﬁltration both short-chain and long-chain zwitterionic moieties has

(MF) membrane [95], polypropylene MF or nonwoven been readily achieved via surface-initiated thiol-ene cou-

fabric membrane [96–99], polytetraﬂuoroethylene (PTFE) pling chemistry [119,120] and azide-alkyne cycloaddition

MF membrane [100], polyethersulfone (PES) ultraﬁltra- reactions [121,122].

tion (UF) membranes [101,102] and polysulfone (PSf) UF The physical blending and adsorbing of zwitterionic

membranes [103]. However, the high-energy excitation copolymers with membrane forming polymers are facile

will also cause undesirable branched or cross-linked brush methods for surface zwitterionization. Considering that

structure and photodegradation of substrate membrane zwitterionic brushes have the characteristics of high water

[104]. In comparison, chemical-initiated graft polymeriza- afﬁnity, several amphiphilic zwitterionic copolymers were

tion is considered to be more moderate and requires no synthesized and employed to increase the stability of

special equipment. Zhang et al. [105,106] grafted zwitteri- zwitterionic brushes with the mediation of hydrophobic

onic SBMA and CBMA monomers from the surface of PVDF interaction between hydrophobic chains and membrane

membranes via physisorbed free radical grafting technique matrix. During the process of membrane preparation by

using azo-bis-isobutyrylnitrile (AIBN) as initiator. Besides, in situ blending, the amphiphilic zwitterionic copolymers

grafting of zwitterionic MPC and MPDSAH monomers from can induce surface segregation of zwitterionic brushes onto

hydroxyl-containing membrane surface was also carried membrane surface with hydrophobic chains anchored in

out using ceric ammonium nitrate as a redox initiator in an membrane matrix [123–132], the mechanism of which will

aqueous medium [107,108]. Still, challenges exist for the be introduced in Section 3.3.3. During the membrane mod-

high grafting densities and uniform zwitterionic brushes iﬁcation process, the amphiphilic zwitterionic copolymers

due to the steric effect of already grafted monomers. can be adsorbed on membrane surfaces with hydrophobic

In recent years, surface-initiated controlled radical poly- chains anchored on membrane surfaces [133–136].

merization, such as surface-initiated atom-transfer radical With the diversiﬁcation of surface modiﬁcation method,

polymerization (SI-ATRP) and surface-initiated reversible other innovative techniques or chemical reactions have

addition-fragmentation chain transfer polymerization (SI- been applied to construct composite zwitterionic mem-

RAFT), has been widely employed to produce well-deﬁned brane surfaces, such as interfacial polymerization of

zwitterionic brushes on membrane surfaces. Surface zwitterionic amide monomer [137,138], oxidative poly-

zwitterionization via surface-initiated controlled radical merization of zwitterionic amino acid 3,4-dihydroxy-l-

polymerization has been widely used, and the combi- phenylalanine (DOPA) [139,140], initiated chemical vapor

+ −

nation of different cationic/anionic pairs (N (CH3)2/SO3 deposition of zwitterionic polymers [141], and chemical

+ − + −

[109–116], N (CH3)2/COO [117], N (CH3)2/PO4 [118]) cross-linking of zwitterionic colloid particles [142,143].

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1681

Membrane surface zwitterionization could also be [17,22,150,151]. So far, mimicking the structure of bio-

derived from membranes containing pyridine [144] logical channels in cell membrane for the fabrication of

or N,N-dimethylamino-2-ethylmethacrylate (DMAEMA) artiﬁcial membranes with various functions and high per-

[145–147] moieties with tertiary amine reactive sites, formance has been of immense scientiﬁc and technological

which could be quaternized and converted to zwitter- interest [152,153].

ionic structures via reaction with propane sultone or

3-bromopropionicacid.

3.2.1.1. Fabrication of membranes via incorporating biolog-

3.1.1.2. Fabrication of membranes via surface glycosylation. ical channel proteins. The most immediate approach to

Highly hydrated glycocalyx lies outside the cell membrane construct biomimetic channel is to imitate the composition

and contributes to direct speciﬁc interactions (cell–cell and structure of cell membrane, i.e. embedding biological

recognition) and prevent undesirable non-speciﬁc pro- channel proteins in bilayer lipid membrane (BLM), which

tein adhesion via a combination of steric repulsion is a simpliﬁed model of the phospholipid bilayer in cell

effects and hydrogen bond indicated hydration [148]. In membrane [151]. Nevertheless, low stability is the inher-

case of biomimetic and bioinspired membranes, some ent drawback of BLM. As a solution, supported BLM on

glycopolymers or glycolmonomers have been used as various porous substrates are adopted [151,154–159]. The

biomimetic materials for membrane surface glycosylation. most frequently used substrates are gold [157] or other

Owing to the glycoside cluster effect and fouling resistant metal thin layers [154], glass, silicon [155], Si3N4, and

nature of glycocalyx on membrane surfaces, the objec- polymers [156,158]. Compared with organic substrates,

tives of surface glycosylation are the speciﬁc recognition inorganic porous substrates have more advantages in terms

of proteins or the prevention of nonspeciﬁc interactions of mechanical, chemical, thermal stability and lifetime

between proteins and membrane surfaces by generating [160]. Furthermore, the self-assembly of block copolymer

extended hydroxyl group rich chains surrounded with as another approach to form bilayer can be an alternative

water molecules. Xu and coworkers [149] have carried out of BLM for its higher stability, controllability, and ability

systematic researches on membrane surface glycosylation to prevent the direct contact of protein to solid substrate,

and recently contributed to a review paper comprehen- which otherwise will immobilize and inactivate the pro-

sively focused on biomimetic glycosylated membranes. To teins [160–163].

avoid overlapping with the existing reviews, we will not go The biomimetic membranes mentioned above can be

into membrane surface glycosylation exhaustively. fabricated through different methods such as vesicle

rupture [159,160,162,163], Langmuir–Blodgett/Langmuir–

3.1.2. Challenges and shortcomings Schaefer monolayer transfer methods, and spin-coating.

Although many extensive researches have been made Among them, vesicle rupture is a simple and commonly

on membrane surface zwitterionization and glycosyla- used technique. The schematic process of fabricating

tion, most of the researches were still carried out in biomimetic membrane by vesicle rupture is shown in

the lab-scale. Firstly, the scale-up of advanced poly- Fig. 14. Firstly, vesicle incorporated channel proteins are

mer synthesis/modiﬁcation strategy are challenged by formed by a ﬁlm rehydration method (Fig. 14a). Afterwards,

precision control of reaction conditions, such as veloc- the solution of vesicles were prepared and dropped onto

ity/temperature/residence time/catalyst distribution in substrates (Fig. 14c). Then the vesicles rupture through

reactors. Secondly, zwitterionic moieties are often too interfacial adsorption or covalent interaction, and the pla-

expensive to use at large quantity and the cheap, easily nar bilayer membranes are obtained (Fig. 14d) [160,162].

available zwitterionic moieties await for the breakthrough In order to form suitable interactions with solid substrates,

in chemical synthesis. Additionally, glucosyl moieties can the polymers constructing bilayers should be functional-

be mostly threaten by microbial degradation during long- ized without changing their self-assembly structure and

term, repeated use. Finally, the fundamental understanding functionality [160]. Besides, the substrates also need to

of membrane structural evolution with different condition be functionalized to be chemically active. In the previ-

has not been clearly explored. Nevertheless, membrane ous works of Chung et al. [160,162,163], diverse triblock

surface zwitterionization and glycosylation will undoubt- copolymers end-functionalized with acrylate, methacry-

edly provide the most promising prospect for biotechnical, late and disulﬁde groups were fabricated to interact with

environmental and engineering applications of membrane amine, silanization modiﬁed substrate and gold coated

technology. substrate via covalent interaction, respectively. Gold is

often chosen as a surface modiﬁer for the substrates

3.2. Based on structures of natural prototypes because it is stable, not cytotoxic, and highly active which

can react with polymers and provide reaction sites for

3.2.1. Based on biological channel further modiﬁcation [151]. As shown in Fig. 14b, poly-

There exist abundant channels formed by proteins carbonate tracked-etched membranes are coated with a

or protein assemblies in cell membrane which make gold layer to achieve the subsequent chemisorption of

the major contributions to the transmembrane transport cysteamine monolayer and the conversion to acrylate.

of ions, nutrients, and water [17,150]. The controllable The enhanced stability of biomimetic membrane can be

rapid and speciﬁc transport of ions, water and other acquired through the formation of covalent interactions

nutrients through biological channels guarantees the between the methacrylate groups on triblock copolymer

essential vital movements in organisms proceed normally and acrylate groups on substrate.

1682 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

Fig. 14. Schematic diagram of pore-spanning membrane design and synthesis.

Most recently, Chung et al. [164] and Tang et al. [165] [169], organic nanotubes by self-assembly [170], anodic

employed interfacial polymerization and layer-by-layer aluminum oxide (AAO) [171] and titania nanotube (TNT)

(LbL) self-assembly to produce robust and defect-free [151] by anodic oxidation, carbon nanotube (CNT) by

AQP-containing membranes that can be easily scaled up. chemical vapor deposition (CVD) [172] and so forth.

AQP-containing proteoliposomes were prepared ﬁrstly and Compared with top-down route, this route can prepare

then embedded into the membrane matrix, which ren- membranes with higher pore/channel density, which

dered a stable and compatible environment for AQP. These is advantageous for molecular separations and other

studies offered new approaches to fabricate biological research ﬁelds that need a large area of channel array

channel proteins-containing membranes with high efﬁ- [151]. For instance, AAO porous template could have a

15 −2

ciency. The distinct difference from the previous studies pore/channel density of 10 m , while TNT membrane

13 −2

was that AQPs acted as the dispersed phase in membrane, also got a 5–10 × 10 m pore/channel density, which

and did not penetrate the entire membrane. are even higher than ion-channel density in natural cells

12 −2

(nearly 10 m ) [151].

3.2.1.2. Fabrication of membranes via constructing arti- Nanopore/nanochannel refers to the pore or chan-

ﬁcial nanopores/nanochannels. Artiﬁcial nanopores/ nel with diameter in the range of 1–100 nm, which is

nanochannels with functional groups can act as analogs larger than the sizes of ions and molecules in most

of biological channel proteins for their mechanically and cases. Therefore, functionalization of inner surface or

chemically robust properties [151,166], high stability, entrance is necessary to decrease the effective size of

great ﬂexibility in terms of shape and size, as well as the nanopore/nanochannel or act as the smart “gate” resem-

tunable surface properties [166]. bling ion channels in cell membrane [173], thus achieving

Membranes with artiﬁcial nanopores/nanochannels the selective permeation ultimately. Moreover, for the

can be fabricated via top-down and bottom-up applications of nanoporous membrane in energy conver-

routes, which refer to making engineered solid-state sion or biorecognition, inner modiﬁcation is often required

nanopores/nanochannels on nonporous substrates by to immobilize or recognize biomolecules. A predominantly

micro-machining, and forming nanopores/nanochannels utilized approach is to immobilize functional molecules

by self-organization of atoms or molecules, respectively onto the interior surface of nanopores/nanochannels

[151]. The top-down route mainly includes electrochemical by various chemical covalent reactions [166,168,174].

etching, electron beam, laser and ion-track-etching tech- For instance, the Au nanopores/nanochannels are often

nologies, through which nanopores/nanochannels with modiﬁed by molecules bearing SH or S S groups to

different shapes and sizes on both inorganic and organic form S Au bonds, and oxides surface can be modi-

substrates can be obtained [167]. All of the technologies ﬁed by various silane derivatives [168]. Other methods

have been introduced in previous reports [166,168] and for nanopores/nanochannels modiﬁcation include electro-

will not be described speciﬁcally in this review. The static self-assembly [175], plasma modiﬁcation [176], as

nanopores/nanochannels fabricated via bottom-up route well as the deposition of metals by electroless deposition,

include hexagonally packed cylindrical block copolymer ion sputtering deposition, or electron beam evaporator

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1683

Fig. 15. (a) Simpliﬁed description of the brush-modiﬁed cylindrical nanochannel. Also indicated in the scheme is the chemical structure of poly(4-vinyl

pyridine) brushes. (b) pH-dependent pyridine–pyridinium equilibrium taking place in the brush environment. (c) Simpliﬁed illustration indicating the

conformational changes occurring in the brush layer upon variations in the environmental pH.

[177]. Fig. 15 shows a simple example of inner surface mod-

iﬁed nanochannel with pH-response by chemical covalent

reaction. Cylindrical nanochannels with a diameter of

15 nm on poly(ethylene terephthalate) (PET) membrane

were ﬁrstly obtained by ion-tracked technology. Then,

the nanochannels were modiﬁed with 4,4 -azobis(4-

cyanopentanoic acid) as a surface-conﬁned polymerization

initiator, and 4-vinyl pyridine as the monomer to form pH-

responsive polymer brushes [166]. The brushes can change

between the swollen, charged hydrophilic state and the

collapsed, neutral hydrophobic state upon alternating the

environmental pH between 2 and 10.

Xu et al. [169] fabricated thin membranes contain-

ing subnanometer organic nanotubes via the synergistic

coassembly of nanotube subunits (cyclic peptide, 8CP) and

block copolymers (BCPs). As shown in Fig. 16, polymers

were tethered onto 8CP ﬁrstly to increase solubility and

mediate the interactions between 8CP and one part of

BCP. After blending with BCPs, the 8CP–polymer conjugates

were conﬁned in BCP cylindrical microdomains which had

afﬁnity with the polymers and assembled into nanotubes

subsequently in the nanoscopic domains upon heating

by the hydrogen bonding between amino acid residues

on adjacent peptides. Finally, the membranes with sub-

nanometer channels oriented normal to the surface were

fabricated. The size and shape of the nanotubes can be tail-

ored by varying the molecular structure of the nanotube

subunits and beyond the limitation of block copolymer self-

assembly. Consequently, the rapid and selective molecular

transport can be achieved.

Among the various artiﬁcial nanopores/nanochannels,

CNT attracts more attentions and acts as an alternative

Fig. 16. Schematic illustration of the process to generate subnanometer

of both biological ion channel and water channel for the porous ﬁlms via directed coassembly of cyclic 8CP and a BCP forming

hydrophobicity, narrow-diameter and inherent smooth- cylindrical microdomains.

ness of the inner surface [178]. CNT has been investigated

American Chemical Society.

extensively since it was found in 1991, and applied in mem-

brane for the ﬁrst time by incorporating aligned CNT in

1684 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

polystyrene (PS) matrix to measure the diffusion of N2 and leave the self-assembly structure unaffected; (2) the activ-

Ru(NH3)6 in CNT in 2004 [172]. The potential applications ity of channel proteins must be maintained, which restricts

of CNT in various membrane processes, and the transport the conditions of preparation process [158,162]; (3) it is

mechanisms of ions and water in CNT have been studied difﬁcult to prepare defect-free bilayer in large-scale pro-

by molecular dynamics (MD) simulation [178–182]. It is duction [159,162]; (4) the cost is high due to the complex

stated that water molecules show single-ﬁle transport in process to extract proteins.

CNT due to the formation of robust hydrogen bond chain, Although nanoporous membranes with artiﬁcial

which resembles the water transport observed in AQP nanopores/nanochannels hold great promise for sep-

[180,181]. Hence, the water transport rate in CNT is com- aration applications due to their higher stability, they

parable to that in AQP [180,181]. In order to acquire high encounter several common challenges. For the mem-

selectivity, CNTs are often modiﬁed with organic groups in branes utilizing top-down routes, the homogeneous

the entrance to obtain decreased effective diameter and modiﬁcation of interior surfaces through the entire

selective interactions with ions [178,183]. Although the nano-scale channels, and the large-scale modiﬁcation are

practical applications of CNT-containing membrane, which difﬁcult to perform. Moreover, the relatively low channel

employs the nanochannels in CNT, is still very few, it has density and the expensive equipment also limited their

drawn growing attention, and will usher promising devel- applications. Among the membranes utilizing bottom-

opment. up routes, CNT-containing membranes drew the most

Due to the mechanical robustness, high control- research interests for its ultrahigh water permeability in

lability, as well as high channel density, biomimetic theory. Nevertheless, the difﬁculty to fabricate large-scale

membranes with artiﬁcial nanopores/nanochannels may membranes with aligned CNTs and the low selectivity

win extensive applications particularly in size-selective limited their development from theoretical research to

separations. practical application.

3.2.1.3. Fabrication of membranes via incorporating 3.3. Based on formations of natural prototypes

both biological channel proteins and artiﬁcial nanopores/

nanochannels. Besides the two types of porous biomimetic 3.3.1. Based on biomineralization

membrane described above, the membranes with hybrid Fabrication of biomimetic and bioinspired membranes

biological and artiﬁcial nanopores/nanochannels have based on biomineralization means inducing the forma-

also been explored [150,184]. In this type of biomimetic tion of inorganic nanoparticles within polymeric matrix

membranes, biological channels can offer an atomically through mineralization reaction resembling the biomin-

precise structure and intelligence resembling that in eralization process in vivo, thus achieving the in situ

living cells, while artiﬁcial nanopores/nanochannels offer fabrication of organic–inorganic hybrid membranes under

robustness, durability, size and shape control [184]. mild conditions.

Henn et al. [150] ﬁlled ion channel protein Gramicidin-A In the past decades, the organic–inorganic hybrid

in the track-etched nanopores (with a diameter of 15 nm) membrane has obtained tremendous concern and wide

on polycarbonate thin ﬁlm and measured the ion diffu- applications because it combines the rigidity and sta-

+ + 2+ 2+

sion coefﬁcient of Na , K , Ca and Mg ions to determine bility of inorganic moiety, with the versatility and

the permeability and selectivity of the nanoporous mem- good membrane-forming property of polymeric moiety

brane. The adsorption of Gramicidin-A in the nanopores [185,186]. Meanwhile, it generates some new properties

was favored by the surface hydrophilic treatment with arising from the hybrid structure.

ethanol, which led to the higher afﬁnity of Gramicidin- The simplest approach to fabricate hybrid membrane

A toward hydrophobic pores than toward hydrophilic is physical blending of inorganic nanoparticle and poly-

surface. Although the effective ion diffusion coefﬁcients mer, which is easy to process and regulate. Nevertheless,

were increased after the incorporation of Gramicidin-A, it the formation of nonselective voids as a result of the

was not as much as it might be. The explanation about agglomeration of inorganic nanoparticles and their poor

this result was that the nanopores were not fully ﬁlled compatibility with polymeric matrices is a drawback which

with Gramicidin-A, so the ions also diffused in the “free” cannot be neglected [187,188]. Another commonly used

electrolyte inside the nanopores. Therefore, further exper- approach named in situ sol–gel process could conquer

imental works are still required to ﬁll out the entire above problem, during which the hydrolysis and poly-

nanopores. condensation of the inorganic precursors occur under the

catalysis of acid or base to form inorganic nanoparticles in

3.2.2. Challenges and shortcomings polymeric casting solutions [189]. Compared with phys-

The performance of a biomimetic nanoporous mem- ical blending, the inorganic nanoparticles disperse more

brane mainly depends on the membrane integrity, the homogeneously and have better compatibility with poly-

channel density in membrane, and the efﬁciency of chan- meric matrixes. However, the sol–gel approach suffers

nels [159]. Although great efforts have been devoted to from the intrinsic drawbacks including harsh conditions

fabricating biomimetic and bioinspired membranes by (strong acid or alkali environment) and poor controllability

incorporating biological channel proteins, there are still [186]. The biomineralization process in vivo combines inor-

some challenges existed for their practical applications: (1) ganic materials with organics, and forms materials with

the channel density in membrane is not well controlled hierarchically complex structure and desirable physico-

[159], hard to determined [161] and limited in order to chemical properties at normal temperature and pressure,

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1685

almost neutral pH, and aqueous environment with sim- diameter less than 100 nm were formed homogeneously

ple chemical compositions [29,37,190]. Their functions are in gelatin matrix. Jiang et al. [199] employed chitosan

far superior to many artiﬁcially synthesized materials due (CS) as inducer to control the formation of CdS nanopar-

to the precise control over the structure, size, shape, and ticles for its excellent adsorption capacity of metal ions

assembly of the constituent parts [29,37,38]. The biominer- [200]. When mixing chitosan with CdCl2 solution, the

alization process in nature renders a wonderful inspiration CS–Cd complexes formed through the adsorption and

source for the facile fabrication of hybrid membranes. chelation of the amino and hydroxyl groups on chitosan

with Cd ions [200]. After the adsorption and chelation

3.3.1.1. Biomimetic mineralization. Biomimetic mineral- balance was achieved, fresh sulfocarbamide solution was

2−

ization means simulating the biomineralization approach dropped slowly. Then S ions were slowly released from

2+ 2+

in the material-synthesizing process, and utilizing organ- sulfocarbamide, and reacted with the Cd ions in CS/Cd

ics to induce the generation of inorganic nanoparticles, complexes to form chitosan/nano-CdS (CS/n-CdS). In the

thus fabricating materials with unique microstructure and above membrane fabrication processes, gelatin or chitosan

properties [37]. Inorganic precursor and organic inducer exhibited at least three functions: forming the ultrathin

are essential substances for the biomimetic mineralization membrane scaffold, inducing the in situ generation of inor-

process. The inorganic precursor can be metal salt or metal ganic nanoparticles, conﬁning the growing of inorganic

alkoxide. The organic inducers can be macromolecules or nanoparticles within the polymeric network and suppress-

small molecules with adequate functional groups to trig- ing their aggregation.

ger the reaction of inorganic precursors such as the amino For membrane-forming polymers without

group for silica and titania [186,191], as well as carboxylate, mineralization-inducing groups, there are two commonly

phosphate and sulfate groups for calcium carbonate and used strategies to implement biomimetic mineralization:

calcium phosphate [192]. For instance, the commonly used grafting functional groups on the polymers or adding other

inducers for the formation of silica include macromolecules organic inducers into the casting solution. By comparison,

like protein [186,193] and small molecules including some the latter strategy seems much easier, but the organic

types of amino acids and amines [194,195]. inducer must be chosen appropriately. If the catalytic

The in situ biomimetic mineralization is an attractive activity of inducer is too high, which means the inorganic

strategy for fabricating hybrid membranes, because it can nanoparticles form too fast, the nanoparticles will grow up

deter the ﬁller agglomeration and inhomogeneous ﬁller and aggregate in a short time, and then precipitate before

distribution in physical blending approach, as well as the casting membrane. Moreover, the added inducers should

harsh conditions (strong acid or alkali environment) and be compatible with the membrane-forming polymers in

poor controllability in in situ sol–gel approach [186,196]. certain range of compositions.

Two methods have been developed to fabricate hybrid In the fabrication of silica-containing hybrid mem-

membrane via in situ biomimetic mineralization. One is branes, amino group or analogous cationic groups are

simply adding inorganic precursor and organic inducer into indispensable. Liu et al. [201] and Xu et al. [202] imple-

the solution which contains membrane-forming polymer, mented quaternized modiﬁcation to poly(vinyl alcohol)

thus making the mineralization process occur simulta- (PVA) and poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO),

neously with the membrane formation process. The other respectively. The quaternary ammonium groups in poly-

is immersing the membrane with inducers into precursor- mers induced the formation of silica from different silica

containing solution. In both methods, organic inducers ﬁrst sources, and the network formed by silica and polymers

interact with inorganic precursors through electrostatic during the reaction rendered the hybrid membranes more

attraction or metal–organic chelation. As a result, inorganic compact. Functionalizing polymers with adequate neg-

precursors are enriched in the micro-domains near organic atively charged groups devote an approach of inducing

inducers, which provide appropriate places and conditions and controlling the formation of CaCO3 nanoparticles.

for the mineralization reaction, and then form inorganic Volkmer et al. [192] utilized hyperbranched polyglycidol

nanoparticles homogeneously. Our group has explored (hb-PG) functionalized with different groups (phosphate

diverse hybrid membranes employing both methods with monoester, sulfate and carboxylate groups) to prepare

different types of membrane-forming polymers, organic CaCO3 hybrid membranes via spray technique. It was

inducers and inorganic precursors [186,193,196–198]. revealed that the type of functional group exerted sig-

niﬁcant inﬂuence on the morphology and structure of

3.3.1.2. Fabrication of membranes via biomimetic miner- CaCO3. As shown in Fig. 17, the sulfate, carboxylate, and

alization during membrane formation. Blending of raw phosphate-ester-functionalized hb-PG led to the formation

materials is a simple approach to fabricate hybrid mem- of vaterite, calcite–vaterite composite, and calcite, respec-

branes via in situ biomimetic mineralization. Jiang et al. tively.

[186] fabricated gelatin–silica hybrid membranes by dis- Jiang et al. [198] fabricated silica-containing hybrid

solving gelatin and sodium silicate in water and then membrane by adding other organic inducers to the

solidifying the casting solution. In the solution, the posi- membrane casting solution. As a widely used membrane-

tively charged amino groups on gelatin molecules absorbed forming polymer, PVA is not able to induce the silica

silicic acid oligomers generated from sodium silicate formation, and meanwhile gelatin is a well-known siliﬁ-

via electrostatic attractions, which increased the local cation inducer and compatible with PVA at low content.

oligomer concentration and then accelerated the polycon- Therefore, gelatin was chosen as the inducer and added into

densation process. As a result, silica nanoparticles with the the PVA solution with the mass ratio of 9/1 (PVA/gelatin),

1686 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

Fig. 17. The molecular structure of hb-PG and SEM micrographs of CaCO3 hybrid membranes formed in the presence of differently functionalized hb-PGs.

then the membrane casting solution was prepared simply templates in protamine aqueous solution for several min-

by mixing the precursor silicate solution with PVA–gelatin utes, and then suspended them in silica source or titanium

solution. Ultimately, silica nanoparticles were generated source solutions subsequently after washing away the

homogeneously within the network of PVA chains. residual protamine. As a result, the inorganic silica or tita-

Biomimetic mineralization is a water-demanded pro- nia layer formed on the outside surface.

cess due to the participation of water in the reaction and In the cases that the inducers exist in the matrix

the water-solubility of inducers. Therefore, hybrid mem- of membrane, including the membrane-forming poly-

branes cannot be obtained by above methods for water mers possess mineralization-inducing functional groups or

insoluble polymers, in which case organic solvents are the inducers are blended and ﬁxed in membrane, inor-

necessary to dissolve polymers. To solve this problem, ganic nanoparticles can form in the membrane matrix

Jiang et al. [196] constructed W/O reverse microemul- after immersing the membrane in precursor-containing

sion through the addition of surfactant and trace water in solutions [193,206,207]. It is worth mentioning that min-

organic casting solution. Water soluble inducer contacted eralization occurs only if the precursors diffuse into

with oil soluble inorganic precursor in the interface of the membrane matrix and contact with the inducers,

two phases, induced the hydrolysis–condensation reaction, which means that the diffusion and reaction take place

and then formed silica nanoparticles in conﬁned space (as synchronously. Therefore, the distribution of inorganic

shown in Fig. 18), thus fabricating hydrophobic/oleophilic nanoparticles is closely related to the structure of mem-

polymer–silica hybrid membrane. The construction of brane matrix and the rate of mineralization reaction.

W/O microemulsion made the major contributions to Generally, the content of inorganic components in mem-

the realization of biomimetic mineralization process in brane gradually decreases from the surface to the interior.

hydrophobic/oleophilic polymer solution: ﬁrst, the water Kumar et al. [207] immersed CS membrane in simulated

in microemulsion can dissolve inducers; second, water is body ﬂuid (SBF) for three weeks to fabricate hydroxyapatite

indispensable for the hydrolysis reaction of silica precur- (HA). The cationic groups in CS membrane contribute to the

3−

sors; last, the water/oil interface provides reaction sites for adsorption of PO4 ions and the consequent nucleation.

the mineralization process. Jiang et al. [193] ﬁxed inducer protamine in the conﬁned

spaces formed by cross-linked PVA molecular chains. When

immersing the PVA-protamine membrane into precursor-

3.3.1.3. Fabrication of membranes via biomimetic mineral-

containing solutions, the inorganic precursor diffused into

ization after membrane formation. Immersing the mem-

the membrane matrix, and then formed silica nanopar-

brane with inducers into a precursor-containing solution is

ticles under the templating and catalysis of protamine

a post-treatment approach to fabricate hybrid membranes

(Fig. 19). The size of silica nanoparticles could be conve-

via in situ biomimetic mineralization. Inducers can exist on

niently adjusted by altering the concentration and pH value

the surface or in the matrix of the membrane, leading to the

of precursor solution. In addition, the formation of silica

different distribution of inorganic nanoparticles. Accord-

could be inﬂuenced by tuning the structure of membrane

ing to the existing reports, small molecular inducers like

matrix, such as varying the annealing temperature to reg-

amino acids are rarely used in this case due to their small

ulate the cross-linking of PVA and bulk polymer network

size and weak interactions with membranes, which make

(Fig. 20).

them prone to leaching out in aqueous solutions.

In summary, biomimetic mineralization provides a

If the inducers are adsorbed just on the membrane

novel, generic strategy to fabricate hybrid membranes with

surface, they will contact with inorganic precursors once

nano-scale ﬁller size, homogeneous dispersion, and desir-

the membrane is immersed into the solution, and thus

able interfacial interactions under mild conditions. With

leading to the formation of inorganic layer on the surface

the increasing researches on the mineralization mecha-

[191,203–205]. Jiang et al. [191,205] fabricated microcap-

nism of various biominerals, biomimetic mineralization

sule membranes by this method. They dispersed sacriﬁcial

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1687

Fig. 18. The formation mechanism of silica mediated by macromolecule inducer in reverse microemulsion.

will win greater development space in the fabrication of may lead to undesirable interfacial compatibility and weak

diverse hybrid membranes. interfacial interaction between the layers. In practical

applications, when the swelling degrees of the two lay-

ers are inconsistent, a large stress will emerge on the

3.3.2. Based on bioadhesion

interface. The stress may cause the two layers to peel off

Besides separation performance, stability is a critical

easily if it exceeds the interfacial interaction. Enhancing

index in investigating the practicability of a membrane.

the interfacial compatibility and the interfacial interac-

For composite membranes comprising two different lay-

tion between the two layers is a simple and effective

ers, the discrepant surface properties of the two layers

Fig. 19. The formation process of silica nanoparticles within PVA matrix.

1688 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

Fig. 20. Transmission electron microscopy (TEM) images of silica in the nanohybrid skin layer after annealed at (a) 293 K, (b) 333 K and (c) 373 K.

Fig. 21. Schematic representation of the interfacial interaction in CS/CP/PAN composite membrane.

strategy to achieve high stability of composite mem- carbopol (CP) as an intermediate layer bridging the CS sep-

brane [208–211]. For surface-functionalized membranes, aration layer and the polyacrylonitrile (PAN) support layer

the preservation of functional groups during long-time for the ﬁrst time. CP is a kind of mucoadhesive polymer

operation is a pivotal demand. For membranes with ﬂexible possessing plenty of carboxylic groups ( COOH) that par-

molecular chains and weak interactions between molecu- tially dissociate in water to endow a very ﬂexible structure

lar chains, the membrane structure will deteriorate when and high viscosity at low concentrations. Fig. 21 shows the

being exposed to water, solvent or other plasticizers during schematic representation of the interfacial interaction for

utilization, which consequently lowers the selectivity sig- CS/CP/PAN composite membrane: besides van der Waals

niﬁcantly. Increasing the cohesive energy of membrane is force, the carboxy group ( COOH) of CP, the hydroxyl group

valid to preserve the membrane structure and improve the ( OH) and the amino group ( NH2) of CS, as well as the

membrane stability. Inspired by the high strength, control- cyano group ( CN) of PAN can form abundant hydrogen

lable adhesive/cohesive capacity, and broad applicability bonds or electrostatic interactions. After the incorpora-

of bioadhesives, biomimetic adhesion strategies employing tion of CP layer, the highest peeling strength was four

bioadhesives or their analogs (biomimetic adhesives) have times larger than that of CS/PAN membrane. Moreover, the

been adopted to efﬁciently cope with the above-mentioned absolute values of interfacial energy for both CS/CP and

problems. CP/PAN interfaces were higher than that of CS/PAN inter-

face based on MD simulation. All the results revealed that

3.3.2.1. Fabrication of membranes via incorporating bioadhe- the interfacial interaction of CS/PAN composite membrane

sives. Introducing bioadhesives into composite membrane was strengthened by the introduction of CP intermediate

fabrication as an intermediate layer is a facile and effective layer. The SEM images in Fig. 22 revealed that the com-

approach to enhance the interfacial interaction between posite membrane had a distinct three-layered structure

the two layers [209,211]. Moreover, the bioadhesives (separation layer, intermediate layer and support layer).

obtained from nature like gelatin, dextrin, and shellac are The presence of an intermediate layer has multi-

more compliant with the requirement of environmen- functional effects on the structure and properties of the

tal protection. Jiang et al. [209] employed bioadhesive composite membranes: the additional layer may increase

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1689

Fig. 22. SEM images of cross-section: (a) GCCS(30)/CP(0.5)/PAN membrane, (b) GCCS(30)/CP(0.05)/PAN membrane.

the mass transfer resistance for permeating molecules; the by sandcastle worm contain DOPA, which makes the

strong interactions between the intermediate layer and the major contributions to the bioadhesion process [44,214].

other layers inﬂuence the structure of interfaces and the Dopamine is an analog of DOPA with almost the same

stability; the intermediate layer acts as a protective coat- structure and properties. Both DOPA and dopamine can

ing and creates a more compatible surface, which enables perform oxidation and self-polymerization process under

the casting of polymer solution with low concentration, and mild conditions in aqueous environment to form an

then achieves the fabrication of thinner separation layer. ultrathin coating possessing high hydrophilicity, favorable

In the above works, bioadhesives just acted as the bind- biocompatibility and robust interfacial binding force with

ing agent between the separation layer and the support diverse substrates, resembling the functional properties

layer. If some bioadhesive can form a thin membrane with of adhesive proteins in marine organisms [44]. The high

selective separation functions while tightly bound to the structural stability and adhesive capacity of as-prepared

support layer, which means the bioadhesive can act as the coating can be achieved through a multiplicity of physical

separation layer directly, then the composite membrane and chemical interactions including hydrogen-bonding

with simple fabrication procedure, high structural stabil- interaction, metal chelation, ␲–␲ interaction, and covalent

ity, and desirable separation performance can be acquired interaction [54,215].

[212,213]. Polydopamine (PDA) was deposited on different sup-

The bioadhesive acting as the separation layer must port layers (such as PSf [216], PES [208], PTFE [210] and

possess dual functions of adhesion and separation, which ceramic [217]) prior to the formation of separation layer.

have different demands for its physical and chemical prop- The multiple interactions between the intermediate PDA

erties. In order to form strong binding to the support layer, layer and the other two layers ensure the improved inter-

the bioadhesive should own some if not all of the following facial compatibility between the two contrasting layers and

characteristics: (i) numerous polar groups, e.g. COOH and the enhanced stability of membrane structure in long-time

OH; (ii) electronegativity; (iii) high molecular weight; (iv) operation. Recently, Chung et al. [216,217] utilized PDA

ﬂexible chain; (v) moderate surface tension [213]. Mean- layer to create a more appropriate surface for the subse-

while, the bioadhesive should have preferential adsorption quent interfacial polymerization reaction by manipulating

for one of the permeating molecules, desirable free volume the hydrophilicity, surface roughness and pore structure of

distribution and appropriate molecular chain rigidity to the support layer.

achieve high permeability and selectivity. Jiang et al. [213] Besides acting as the intermediate layer,

employed bioadhesive hyaluronic acid, a kind of acidic poly(DOPA)/PDA has also been utilized as the skin

polysaccharide, as the separation layer of composite mem- layer of membrane such as the separation layer of compos-

brane for dehydration of organic solvents due to its high ite membrane [54,215] or the surface modiﬁcation coating

negative charge density, excellent chain ﬂexibility, high [218–225]. Compared with commonly used approaches,

molecular weight, strong afﬁnity to water, and favorable the deposition of poly(DOPA)/PDA is green and efﬁcient

membrane-forming property. Both experimental and MD with desirable durability. Our group [54,215] fabricated

simulation investigations were carried out to conﬁrm the composite membrane with ultrathin and defect-free PDA

favorable interfacial compatibility and strong interfacial separation layer (as shown in Fig. 23) by immersing

interaction of as-prepared composite membrane. the support layer into dopamine aqueous solutions and

making the self-polymerization reaction take place on the

surface. The thickness and structure of separation layer can

3.3.2.2. Fabrication of membranes via incorporating

be regulated controllably through changing coating num-

biomimetic adhesives. Besides the bioadhesives extracted

ber, coating time, as well as the pH value and concentration

from organisms, biomimetic adhesives with similar struc-

of dopamine solution. To date, poly(DOPA)/PDA coating

ture and functional groups can be utilized as substitutions

has been used in membranes with diverse materials and

if the corresponding bioadhesives are difﬁcult and costly to

pore sizes [218–224,226]. In all cases, the hydrophilicity

extract. It has been introduced in Section 2.3 that both the

of membrane acquired obvious improvement, but as to

adhesive proteins in mussel byssus and cement secreted

1690 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

Fig. 23. SEM image of the cross-section area of the PDA/PSf composite membranes: (a) single coating (inset: the uncoated PS membrane), (b) double

coating.

DOPA has a unique characteristic of zwitterionic [140],

which is favorable for constructing surface with high

hydrophilicity.

Poly(DOPA)/PDA derivatives with DOPA/dopamine

grafted on other molecules offers a new surface modiﬁ-

cation approach with facility, diversity, and stability. Gong

et al. [227] integrated the fouling resistance of cell mem-

brane and the anchoring ability of mussel adhesive proteins

by fabricating doubly biomimetic copolymer as anti-

fouling coating, which contains phosphorylcholine (PC)

side-groups and catechol groups simultaneously. Fig. 24

showed that the doubly biomimetic copolymer can be

adsorbed onto various substrates by the strong anchoring

force formed by catechol groups, while the PC groups pre-

sumably orient toward the outside forming the anti-fouling

surface resemble cell membrane. Thus the anti-fouling sur-

faces were fabricated on various materials and devices

Fig. 24. Schematic illustration of the structure and fouling resistance of

by facile dip-coating in the doubly biomimetic polymer

the doubly coating of biomimetic copolymers.

Wiley-VCH Verlag GmbH & Co. KGaA. riority of Poly(DOPA)/PDA is the high reactivity, which

provides reaction sites to achieve further modiﬁcation for

membrane surface. For instance, the catechol group can

the surface roughness, they varied with the pore sizes

chelate with metal ions in the original form [228], and react

on membrane surface. It has been demonstrated that

with thios and amines via Michael addition or Schiff base

poly(DOPA)/PDA-coated layer composed of aggregated

reactions after being oxidized to quinone [44,228,229].

nanoparticles [218]. For MF membrane, the pore sizes

Zhu et al. [229,230] modiﬁed polyethylene (PE) porous

are larger compared with poly(DOPA)/PDA nanoparticles,

membranes with PDA coating and subsequently immobi-

which therefore are formed inside the pores, leading to the

lized heparin and bovine serum albumin (BSA) respectively

surface smoothing [219]. As to membranes with compar-

via covalent bonds in aqueous environment to acquire

ative or smaller pore sizes such as UF, nanoﬁltration (NF)

high hydrophilicity and good biocompatibility. Fig. 25

and reverse osmosis (RO) membranes, the pore blocking

showed the schematic of the PDA deposition on PE porous

takes place and dominates at beginning, leading to the

membranes and the subsequent heparin immobilization.

increase of roughness [221]. Compared with dopamine,

Fig. 25. The schematic of the PDA deposition on PE porous membranes and subsequent heparin immobilization.

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1691

Fig. 26. Schematic illustration of the possible nanoscale structures of hybrid membranes with different Fe /DA. (a) DA monomers bearing abundant phenyl

3+ 3+

groups show high adhesion ability but weak cohesive ability. (b) Low Fe /DA leads to aggregated Fe –DA complexes with enhanced cohesive interaction

3+ 3+

and adequate adhesion ability. (c) High Fe /DA leads to robust Fe –DA nanoaggregates with few available phenyl groups and poor adhesion ability.

Abundant o-benzoquinonyl groups existed on the surface microphase-separate into aggregates of multiple mor-

of PDA layer after the oxidation and self-polymerization phologies with highly ordered structures [234,235], such

of dopamine, which reacted with the amino/imino groups as spheres or cylinders of one phase in a matrix of another,

on heparin upon immersing the membrane into hep- as well as gyroids or lamellar (Fig. 27) [236,237]. Mem-

arin solution. The deposition of poly(DOPA)/PDA and their branes with high ﬂux and selectivity can be fabricated

derivatives provides a convenient approach with facility, with self-assembled block copolymers. Although several

versatility and long-time durability to modify the mem- dense membranes deriving from self-assembly of block

brane surface and incorporate diverse functions, which is copolymer were reported to provide potential application

especially valuable for those membranes with chemical in CO2 membrane separation [238–241], pervaporation

inertness. [242–244] and fuel cells [245–247], most researchers focus

In order to increase the cohesive energy and then the on the manufacture of nanoporous membranes with high

structural stability of membrane, dopamine was incorpo- porosity, narrow pore size distributions, tunable chemi-

rated into membrane matrix as modiﬁer with its oxidation cal and mechanical properties, highly oriented and ordered

and polymerization process occurring before [231], during nanopores. For example, when the molecular weight and

[232], and after [233] the membrane fabrication process, composition of block copolymers are within speciﬁed lim-

respectively. Different oxidizing agents including oxygen, its, the spontaneous self-assemble process can lead to

iron ion, and sodium periodate have been utilized to induce ordered cylinders that are aligned perpendicularly to the

the reaction. The multiple interactions between PDA and surfaces and further transformed into ordered nanoporous

membrane matrix endowed the membrane with elevated membranes [248].

stability. Furthermore, the adhesive/cohesive balance of A wide variety of block copolymers have been used

PDA and the resultant membrane structure can be effec- to generate self-assembled nanoporous ﬁlms since Naka-

tively adjusted by varying the oxidation conditions, such hama ﬁrst fabricated nanoporous polymer ﬁlms from a

as the ratio of oxidizing agent to dopamine, if the forma- siloxane-functionalized polystyrene-b-polyisoprene (PS-

tion of PDA was during or after the membrane fabrication b-PI) system [249].

process (as shown in Fig. 26). Pioneering work has been carried out to fabricate

nanoporous membranes from the self-assembly of PS

3.3.3. Based on self-assembly block copolymers with hydrophilic poly(methyl methacry-

The self-assembly offers an excellent platform for dupli- late) (PMMA) or poly(ethylene oxide) (PEO) blocks. Two

cation of natural manufacturing process from biomimetic methods have been developed to obtain nanoporous

and bioinspired pathways since both share an impor- membranes stemming from their unique ability to self-

tant feature-spontaneous organization: phospholipids and assemble into cylindrical microdomains. The ﬁrst method

biomacropolymer self-assembly. The similar interaction lies in the removal of the minor PMMA component to

mechanisms and structures demonstrate that the self- generated cylindrical microdomains oriented normal to

assembly process dedicates a unique nano-scale method the membrane surface [250–257]. The representative

that allows for ﬁne control of the membrane structures and highly ordered nanoporous thin ﬁlms prepared from

chemistries. In this section, an overview of self-assembly self-assembled PEO-b-PMMA-b-PS were developed via

processes that are currently employed in the fabrication of initial solvent annealing followed by ultraviolet (UV) irra-

ordered nanoporous membranes and the modiﬁcation of diation to degrade the PMMA block [252,253]. The central

polymer membranes is provided. PMMA block endowed degradability and the terminal PEO

block permitted long-range order to the system. These

kinds of nanoporous membranes with narrow pore size

3.3.3.1. Fabrication of membranes via block copolymer self-

distribution had the potential of both high selectivity and

assembly. Synthetic block copolymers comprised of two

high ﬂux for ﬁltration. The second method involves

or more thermodynamically incompatible blocks can

1692 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

Fig. 27. Diagram of the microdomain morphologies of diblock copolymers. As the volume fraction of components in the diblock copolymer is varied, the

diblock copolymer self-assembles into morphologies ranging from spherical (S) to cylindrical (C) to gyroid (G) to lamellar (L). Note that G , C , and S have

the same morphologies but reversed polymer components of the G, C, and S systems.

removing homopolymer from block copoly- copolymer ﬁlm could lead to a perpendicular ori-

mer/homopolymer blends with the homopolymer more entation. Subsequently exposing the composite mem-

conﬁned to the center of cylindrical microdomains brane to a dilute aqueous base could selectively etch

[257–263]. Kim et al. [258] prepared a double-layered the PLA block, producing the porous structure. They

nanoporous membrane from a mixture of PS-b-PMMA also prepared nanoporous membranes from cylinder-

with cylindrical microdomains of homopolymer PMMA. forming triblock copolymer polystyrene-b-poly(dimethyl

The film was firstly assembled on sacrificial silicon oxide acrylamide)-b-polylactide (PS-b-PDMA-b-PLA) and PS-b-

layer, and then released in HF solution, transferred onto PI-b-PLA by etching the PLA block [248,266,267]. For

the PS membrane, and ﬁnally treated by selectively engineering tough nanoporous membranes, they demon-

removing the PMMA homopolymer from the cylindrical strated a novel approach to produce robust bicontinuous

PMMA microdomains with acetic acid (Fig. 28). An 80 nm nanoporous block copolymer self-assembled membranes

thick membrane was obtained with cylindrical pores of by ring-opening metathesis polymerization of norbornene-

diameter 15 nm for virus ﬁltration. functional PS-b-PLA and dicyclopentadiene (DCPD) addi-

Polylactide (PLA) represents an exciting class of base tive (polymerization induced phase separation), followed

degradable blocks and a versatile moiety in forming by selective removal of PLA block [268,269]. The cross-

well-ordered nanoporous block copolymer membranes. linked nanoporous membranes with narrow pore size

Hillmyer and Cussler developed a strategy for prepar- distributions were obtained. Moreover, PS-based block

ing monodisperse nanoporous membranes templated by copolymer composites (PS-b-PLA and PS-b-PEO) were

block polymer PS-b-PLA self-assembly [264,265]. Care- applied to prepare ordered nanoporous membranes with

ful control of the solvent evaporation rate of the hydrophilic pore surfaces. Pegylated pore surfaces were

Fig. 28. Schematic depiction of the procedure for the fabrication of asymmetric nanoporous membranes by removing homopolymer from block copoly-

mer/homopolymer blend ﬁlms.

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1693

Fig. 29. Preparation strategy of the nanoporous PE membrane whose pore wall is lined with PMe(OE)xMA by the PLA selective etching from the reactive

block copolymer blends.

prepared by the degradative removal of PLA block from a ﬁlms from PS-b-PEO block copolymer bearing a photo-

self-assembled PLA/PEO microdomains. Both hexagonally cleavable o-nitrobenzyl ester junction [274]. Russell et al.

packed cylindrical morphology [270] and bicontinuous [275] presented nanoporous ﬁlms from poly(styrene-ss-

gyroid morphology [271] were adopted depending on dif- ethylene oxide) (PS-ss-PEO) connected by a redox cleavable

ferent annealing conditions. PE-based block copolymer disulﬁde bond. After annealing in a benzene/water vapor

composites could also be used to create nanoporous mem- environment, the PS-ss-PEO ﬁlms oriented the PEO cylin-

branes with hydrophilic pore surfaces by crystallization- drical microdomains normal to the ﬁlm surface and the

induced self-assembly and subsequently PLA removal. PEO block could be easily cleaved by simply immersing PS-

The block copolymer composites of PLA-b-PE-b-PLA ss-PEO thin ﬁlms in a d,l-dithiothreitol-containing ethanol

and poly(2-(2-methoxyethoxy) ethyl methacrylate)-b- solution, generating nanoporous thin ﬁlms (Fig. 30). Films

polyethylene-poly(2-(2-methoxyethoxy) ethyl methacry- assembled from PS-b-PEO possessing a cleavable triph-

late) (PMe(OE)xMA-b-PE-b-PMe(OE)xMA) were reported enylmethyl ether juncture between PS and PEO could also

to produce a disordered bicontinuous structure with a create nanopores by the selective removal of PEO via tri-

mixed PLA/PMe(OE)xMA domains and a semicrystalline PE ﬂuoroacetic acid etching [276].

domains. A selective PLA etching from PLA/PMe(OE)xMA Another elegant method derived from block copoly-

domains by mild base treatment would successfully build mer supramolecular assemblies with hydrogen bond

a nanoporous PE having pore walls lined with PMe(OE)xMA donors and acceptors has been employed to create

polymer chains (Fig. 29) [272]. ordered nanoporous membranes via eliminating the minor

Self-assembled unique block copolymer with a cleav- component enriched nanodomains. Ikkala and Brinke

able covalent linking unit in the middle of the block et al. [277–279] used hydrogen bonding between 4-

copolymer have the potential of the successful removal of vinylpyridine monomer units and 3-pentadecyl phenol

minor component domains without the use of harsh chem- (PDP) to create a comb-like molecular architecture and

icals. Moon et al. [273] have demonstrated a novel route modify the gyroid/cylinder morphology of polystyrene-b-

to fabricate nanoporous PS ﬁlms using a selectively photo poly(4-vinylpyridine) (PS-b-P4VP). Two-dimensional ﬁlms

cleavable PS-b-PEO block copolymer (ONB-(PS-b-PEO)), constructed from these supramolecular assemblies could

in which a photochemically sensitive ortho-nitrobenzyl create nanopore membranes by removing amphiphile

(ONB) group was installed as a photocleavable linking PDP domains by washing with selective solvent (Fig. 31).

unit. The cylindrical PEO domains could be removed after Fahmi et al. [280] also used PS-b-P4VP/PDP comb-like

UV light irradiation and selective solvent rinse. The pro- block copolymer systems to obtain a lamellae-within-

posed strategy was also applied to form nanoporous thin cylinders ﬁlms with well-deﬁned and periodic nanoporous

1694 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

Fig. 30. Structure of the PS-ss-PEO block polymer connected by a disulﬁde bond and schematic representation of the preparation of nanoporous thin ﬁlm.

structures. 2-(4 -hydroxybenzeneazo)benzoic acid (HABA) pyrrolidone) (PVP) block, were also used to construct

was also used as hydrogen bond donors motivated by the ordered nanoporous ﬁlms via self-assembly of block

possibility to achieve thin ﬁlms with perpendicularly ori- copolymer-based supramolecules based on physical inter-

ented hexagonally ordered cylinders of P4VP. Luchnikov actions.

and Stamm [144,281–285] developed the supramolecu- Metallo-supramolecular block copolymers have won

lar assemblies from PS-b-P4VP/HABA system, consisting increasing interest in recent years and are appropri-

of cylindrical nanodomains formed by P4VP-HABA asso- ate to tailor the facile synthetic strategies for various

ciates surrounded by PS. The HABA molecules formed architectures. Fustin’s group [274,291–293] have carried

hydrogen bonds with the P4VP repeat units and evenly out a series of research to develop a simple two-step

dispersed within the P4VP(HABA) domains. The HABA approach to generate nanoporous structure from metallo-

could be easily removed from P4VP(HABA) domains when supramolecular block copolymers with amphiphilic blocks

washed in selective solvent, rendering the ordered array linked together by a metal–ligand complexes (see Fig. 32).

of nanochannels. Moreover, other activities, such as 1- The ﬁrst step involved the self-assembly of the block

pyrenebutyric acid (PBA) [286], dodecylbenzenesulfonic copolymer, yielding cylindrical microdomains oriented

acid (DBSA) [287], poly(methyl methacrylate)-dibenzo- normal to the substrate. The second step involved the open-

18-crown-6-poly(methyl methacrylate) (PMCMA) [288], ing of the metal–ligand complex by redox chemistry to

PMMA, 1,5-dihydroxynaphthalene (DHN) [289], and phe- release the minor PEO block and create the nanopores.

nolic resin [290] that could interact with the poly(vinyl Metallo-supramolecular block copolymers have already

Fig. 31. The schematics illustrate supramolecular self-assembly of PS-b-P4VP triblock copolymers and less than stoichiometric amounts of PDP into a

core–shell gyroid morphology with the core channels formed by the hydrogen-bonded P4VP(PDP) complexes. After structure formation, PDP domains

were removed using a simple washing procedure, resulting in well-ordered nanoporous ﬁlms that were used as templates for nickel plating.

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1695

Fig. 32. Schematic representation of the preparation of functionalized nanoporous thin ﬁlms from metallo-supramolecular block copolymers.

Fig. 33. Schematic diagram of the asymmetric ﬁlm formation process combining NIPS with the self-assembly of block copolymer PS-b-P4VP.

displayed much superiority in that the reversibility of the assembly techniques of block copolymer micelles con-

supramolecular bond endows the “smart materials” with tributed a versatile, facile and nondestructive means to

tunable properties [294]. form mesoporous block copolymer ﬁlms with well-deﬁned

The lack of sufﬁcient long-range order, the difﬁ- pore sizes. Phillip et al. [300] fabricated PI-b-PS-b-P4VP

culty of up-scaling and the time-consuming preparation triblock copolymer-derived mesoporous ﬁlms using a com-

steps pose serious problems for the production of block bination of controlled solvent evaporation (directing the

copolymer-based membranes. The straightforward, fast self-assembly of the terpolymer micelles to template the

and environmentally friendly procedure for membrane for- structure of the mesoporous selective layer) and NIPS (cre-

mation is undoubtedly needed. Peinemann et al. [295] ating the underlying macroporous support structure). The

reported an innovative and facile method to prepare mesoporous ﬁlms displayed distinct stimuli responsive

isoporous membranes with nanometer-sized pores by permeation behavior.

combining non-solvent induced phase separation (NIPS) The conﬁned swelling-induced pore-making process

with the self-assembly of block copolymer PS-b-P4VP has emerged recently as a new strategy to produce porous

(see Fig. 33). The solvent evaporation led to a concen- materials by exposing self-assembled block copolymers

tration gradient of block copolymer solution between the with solvents strongly selective to minority phase. Synergic

interface to the air and the bottom. At the higher concen- advantages include extreme simplicity, high pore regular-

tration region (surface), microphase separation occurred ity, no chemical reactions, no weight loss, reversibility of

and spread along the gradient, thus guiding the growth the pore forming process, etc. [301]. Wang et al. [302,303]

of the cylindrical domains into the still highly swollen reported on bicontinuous nanoporous polystyrene-b-

layer. During the phase separation process, the non- poly(2-vinyl pyridine) (PS-b-P2VP) membranes with sharp

solvent water ﬁrst migrated into the cylindrical domains size selectivity and active surfaces by swelling the minor-

of swollen P4VP blocks and exchanged with solvent in ity P2VP domains of the block copolymer with selective

these domains. The solvent from the swollen PS matrix solvents accompanied by reconstruction of the majority

mostly diffused to the channels because the interface PS component. During the subsequent drying, the swelling

area for the solvent/non-solvent exchange available in P2VP chains shrunk and collapsed, while the expanded vol-

these channels was much larger than that at the top ume of initial P2VP domains was ﬁxated by the glassy PS,

surface. They also described unique approaches to for- leading to the formation of pores along the continuous

mulate isoporous asymmetric membranes tailored by P2VP phase. These pores ranging from a few to several tens

complexation-directed supramolecular chemistry, solvent of nanometers could be tuned by changing the swelling

selectivity, and the supramolecular assembly of PS-b-P4VP conditions, e.g., swelling time, temperature, or using block

block copolymer micelles [296–299]. The supramolecular copolymers with different molecular composition.

1696 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

Fig. 34. (a) Schematic of the osmotic shock process acting on layers of spheres leading to the perforated multilayers. (b) Fracture cross-section of PS-b-PMMA

multilayer structures (scale bar, 200 nm).

Most recently, Zavala-Rivera and co-authors have One of the early reports on surface segregation of

reported a novel method of collective osmotic shock based amphiphilic copolymers for membrane hydrophilization

on self-assembled block copolymer micelles and swelling- was published by Mayes and coworkers [317,318]. They

induced expansion of the minority phase [304]. Spherical employed methyl methacrylate (MMA) and PEO-based

block copolymer, PS-b-PMMA, was used to create materials comb polymer as the surface-segregating additives to

susceptible to collective osmotic shock (Fig. 34a). The PS-b- increase the surface hydrophilicity of poly(vinylidene ﬂuo-

PMMA ﬁlm was built up with several layers of close-packed ride) (PVDF) membrane. PEO side chains have proved to be

PMMA spherical cores, discretely spaced and surrounded enriched onto membrane surfaces, due to the well-known

by a PS matrix. Subsequently exposure to UV light cross- afﬁnity to water. They also demonstrated the good dura-

linked the PS phase and broke the PMMA down to small bility of the surface hydrophilicity, thanks to the so-called

oligomers. Then, the ﬁlm was immersed in acetic acid (a self-healing capacity of surface segregation method [317].

solvent for PMMA oligomers) and generated much higher The PEO brushes removed from the surface during opera-

osmotic stresses within PS matrix because of the solvation tion or cleaning can be substantially regenerated by further

of degraded PMMA oligomers. The collective osmotic shock segregation of the residual amphiphilic additives upon sub-

resulted in the ruptures between the spheres and created sequent heat treatment or others driven by an emerging

a pathway for the complete release of PMMA oligomers. gradient in a chemical potential.

Coordinated explosive fracture within ordered materials Xu and Zhu have also used amphiphilic copoly-

led to nanoperforated multilayer structures (Fig. 34b) that mers as additives with different structures to fabricate

would ﬁnd application in ultraﬁltration and other mem- porous membranes following phase inversion method,

brane processes [236]. such as poly(methyl methacrylate-r-poly(oxyethylene

Based on the discussion in this section, preparation methacrylate)) P(MMA-r-PEOM) [319], block copoly-

of ordered porous membranes via self-assembly of block mers [116,147,320,321], hyperbranched-star polymer

copolymers are brieﬂy summarized in Table 2. This may [322–324] and comb-like copolymer [325–328]. These

serve as a useful reference and guideline for the develop- amphiphilic copolymers enriched at the membrane

ment of ordered porous membranes. surfaces via thermodynamic surface segregation of

hydrophilic chains onto polymer–water interface. They

◦

also annealed the blend membranes in water (60 C)

3.3.3.2. Fabrication of membranes via amphiphilic copolymer

to investigate the retaining stability of the different

surface segregation. As an in situ approach to membrane

amphiphilic polymers on the membrane surfaces [325].

surface modiﬁcation, surface segregation of amphiphilic

Only a slight change in water contact angles was observed

copolymers for membrane surface construction has the

for the blend membranes when the membranes had been

advantages of generating more efﬁcacious brush layers on

leached continuously in hot water for 30 days, suggesting

both membrane surface and pore surface [314]. The surface

the desirable robustness of the membrane surfaces.

segregation technique, as a self-assembly approach, can be

Our group has intensively proposed the use of

described as follows: amphiphilic copolymers are ﬁrstly

a Pluronic block copolymers, poly(ethylene oxide)-b-

blended in membrane casting solution, and during the sub-

poly(propylene oxide)-b-poly(ethylene oxide) (PEO-b-

sequent phase inversion process, the hydrophilic segments

PPO-b-PEO), as surface-segregating additives for prepara-

of the copolymers in proximity to the interface are seg-

tion of fouling resistant PES membranes. Hydrophobic PPO

regated to the membrane surface spontaneously until the

segments in Pluronic block copolymers ﬁrmly anchored

chemical potentials of the bulk and brush layers are bal-

in the PES matrix leading to the wrapping of Pluronic

anced, whereas the hydrophobic parts are ﬁrmly entrapped

block copolymers on PES and the hydrophilic PEO segments

in the membrane matrix through hydrophobic interaction

gradually ﬂoats to membrane surface which endowed

[315,316]. So far, many porous membranes have been fab-

the membranes surface with higher hydrophilicity as

ricated via surface segregation of amphiphilic copolymers

well as good stability (Fig. 35) [329–338]. A similar con-

coupled with the commercially utilized membrane forma-

clusion has also been derived independently by other

tion technique-wet phase inversion.

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1697

Table 2

Fabrication of membranes via block copolymer self-assembly.

Membranes Assemblies and assembly approaches Pore generation References

PS-b-PI PS-b-PI; coating PS-b-PI onto silicon substrates, followed Degrading PI by O3 and methanol rinsing [249]

by solvent evaporation

PS PS-b-PMMA; coating PS-b-PMMA onto PS-r-PMMA neutral Degrading PMMA by UV exposure and [251,256,258]

layer, followed by vacuum high-temperature annealing acetic acid rinsing

and rapid quenching

PS PEO-b-PMMA-b-PS; coating PEO-b-PMMA-b-PS onto Degrading PMMA by UV exposure and [252,253]

silicon substrates, followed by solvent annealing; PEO acetic acid rinsing

block permitting long-range ordering

PS (PS-r-BCB)-b-PMMA; coating (PS-r-BCB)-b-PMMA onto Degrading PMMA by UV exposure and [254]

P(S-r-BCB-r-MMA) neutral layer, followed by thermal acetic acid rinsing

annealing and cross-linking at elevated temperatures

PS PS-b-PMMA; coating PS-b-PMMA onto glass substrates Degrading PMMA by UV exposure and [250,255]

along with fast solvent evaporation acetic acid rinsing

PS PS-b-PMMA/PEO; coating PS-b-PMMA/PEO onto silicon Removing PMMA/PEO domains by UV [257]

substrates, followed by solvent annealing exposure and acetic acid rinsing

PS-b-PEO PS-b-PEO/PAA; coating PS-b-PEO/PAA onto porous Removing PAA by soaking in water [259]

supports along with fast solvent evaporation

PS-b-PMMA PS-b-PMMA/PMMA; coating PS-b-PMMA/PMMA onto Degrading PMMA by acetic acid rinsing [260,263]

PS-r-PMMA neutral layer, followed by vacuum

high-temperature annealing and rapid quenching

PS PS-b-PLA; coating PS-b-PLA porous support, followed by Removing PLA by dilute aqueous base [264,265]

controlled solvent evaporation rinsing

PS-b-PI PS-b-PI-b-PLA; coating PS-b-PI-b-PLA onto Removing PLA by dilute aqueous base [266,267]

hexamethyldisilazane neutral layer or porous supports, rinsing

followed by vacuum high-temperature annealing

PS-b-PDMA PS-b-PDMA-b-PLA; molding PS-b-PDMA-b-PLA, followed Removing PLA by dilute aqueous base [248]

by vacuum high-temperature annealing rinsing

PS NPS-b-PLA/DCPD; cross-linking NPS-b-PLA/DCPD using the Removing PLA by dilute aqueous base [268,269]

Grubbs catalyst, followed by controlled solvent rinsing

evaporation

PS/PS-b-PEO PS-b-PEO/PS-b-PLA; controlled solvent evaporation Removing PLA by dilute base or [270,271]

followed by vacuum high-temperature annealing concentrated HI solution rinsing

PE PLA-b-PE-b-PLA; melt molding, followed by cooling Removing PLA by dilute aqueous base [305]

induced PE crystallization rinsing

PE/PMe(OE)xMA-b-PE- PMe(OE)xMA-b-PE-b-PMe(OE)xMA/PLA-b-PE-b-PLA; melt Removing PLA by dilute aqueous base [272]

b-PMe(OE)xMA molding, followed by cooling induced PE crystallization rinsing

PE PS-b-PE; melt molding, followed by cooling induced PE Removing PS by fuming nitric acid [306–308]

crystallization

PB PB-b-PDMS; coating PB-b-PDMS onto glass substrates Removing PDMS by [309,310]

along with controlled solvent evaporation tetra-n-butylammonium ﬂuoride solution

PS (ONB-(PS-b-PEO); coating (ONB-(PS-b-PEO) onto silicon Removing PEO by UV cleavage of ONB and [273]

substrates, followed by solvent annealing methanol rinsing

PS PS-ss-PEO with disulﬁde juncture; coating PS-ss-PEO onto Removing PEO by DDT cleavage of disulﬁde [275]

silicon substrates, followed by solvent annealing juncture and ethanol rinsing

PS PS-b-PEO with triphenylmethyl ether juncture; coating Removing PEO by triﬂuoroacetic acid [276]

PS-b-PEO onto silicon substrates, followed by solvent cleavage of triphenylmethyl ether juncture

annealing and methanol rinsing

PS PS-b-PEO with o-nitrobenzyl ester juncture; coating Removing PEO by UV cleavage of [274]

PS-b-PEO onto silicon substrates, followed by solvent o-nitrobenzyl ester and methanol rinsing

annealing

PtBOS-b-PS-b-P4VP PtBOS-b-PS-b-P4VP/PDP; coating PtBOS-b-PS-b-P4VP/PDP Removing PDP by ethanol rinsing [279]

onto glass substrates, followed by solvent annealing

PS-b-P4VP PS-b-P4VP/PDP; molding along with vacuum Removing PDP by ethanol rinsing [280]

high-temperature annealing and rapid quenching

PS-b-P4VP PS-b-P4VP/HABA; coating PS-b-P4VP/HABA onto silicon Removing HABA by methanol rinsing [281–285]

substrates, followed by solvent annealing

PS-b-P4VP PS-b-P4VP/HABA; casting PS-b-P4VP/HABA on porous Removing HABA by ethanol rinsing [144]

supports, followed by nonsolvent induced phase inversion

PS-b-P4VP PS-b-P4VP/PBA; coating PS-b-P4VP/PBA onto silicon Removing PBA by ethanol rinsing [286]

substrates, followed by solvent annealing

PS-b-P4VP/DBSA PS-b-P4VP/DBSA/PDP; coating PS-b-P4VP/DBSA/PDP onto P4VP/DBSA domains collapsing upon [287]

silicon substrates, followed by controlled solvent annealing

evaporation

PS-b-P4VP/PMCMA PS-b-P4VP/PMCMA; coating PS-b-P4VP/PMCMA onto P4VP/PMCMA domains collapsing upon [288]

silicon substrates, followed by controlled solvent annealing

evaporation

PS-b-P4VP PS-b-P4VP/DHN; coating PS-b-P4VP/DHN onto silicon Removing DHN by methanol rinsing [289]

substrates, followed by controlled solvent evaporation

1698 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

Table 2 (Continued)

Membranes Assemblies and assembly approaches Pore generation References

Phenolic resin PS-b-P4VP/phenolic resin; coating PS-b-P4VP/phenolic Removing PS-b-P4VP by pyrolysis [290]

resin onto silicon substrates, followed by controlled

solvent evaporation

2+ 2+

PS PS-[Ru ]-PEO; coating PS-[Ru ]-PEO onto silicon Removing PEO by oxidizing the Ru(II) into [291,292]

substrates, followed by solvent annealing Ru(III)

2+ 2+

PS PS-[Ni ]-PEO; coating PS-[Ni ]-PEO onto silicon Removing PEO by methanol rinsing [293]

substrates, followed by solvent annealing

PS-b-P4VP PS-b-P4VP; casting PS-b-P4VP onto glass substrates, Solvent/non-solvent exchange [295–299,311]

followed by initial solvent evaporation and nonsolvent

induced phase inversion

PS-b-PEO PS-b-PEO; casting PS-b-PEO onto glass substrates, followed Solvent/non-solvent exchange [312]

by initial solvent evaporation and nonsolvent induced

phase inversion

PI-b-PS-b-P4VP PI-b-PS-b-P4VP; casting PI-b-PS-b-P4VP onto glass Solvent/non-solvent exchange [300,313]

substrates, followed by initial solvent evaporation and

nonsolvent induced phase inversion

PS-b-P2VP PS-b-P2VP; coating PS-b-P2VP onto silicon or porous Shrinkage of P2VP chains after ethanol [302,303]

supports substrates, followed by controlled solvent swelling

evaporation

PS PS-b-PMMA; coating PS-b-PMMA onto silicon substrates, Degrading PMMA by UV exposure and [304]

followed by high-temperature annealing acetic acid initiated collective osmotic

shock

researchers. Ulbricht et al. [339,340] prepared high per- minimize interfacial free energy. Furthermore, we pre-

formance PES/Pluronic membranes with a high ﬂux and sented a “forced surface segregation” method to in situ

stable hydrophilic character by vapor-induced phase sepa- engineering a porous amphiphilic membrane surface

ration coupled with non-solvent induced phase separation with hydrophilic fouling resistant domains and low sur-

method. Venault et al. [341,342] also reported PEO enriched face free energy fouling release (self-cleaning) domains

PSf and PVDF membranes by the surface segregation of [128,343–345]. Low surface energy segments, such as

Pluronic F108 additives by vapor-induced phase separa- ﬂuorine-containing segments and silicone-segments, are

tion. not able to spontaneously segregate onto the polymer-

Meanwhile, our group has pioneered the design and water interface during NIPS process through the “free sur-

construction of zwitterionic membrane surfaces using face segregation” due to the unfavorable thermodynamics

alternative amphiphilic zwitterionic ligands as surface- [346]. We developed several kinds of amphiphilic copoly-

segregating additives, such as soybean phosphatidyl- mer additives with non-polar low surface energy segments

choline [131,132], sulfobetaine copolymer [129,130], covalently bonded with hydrophilic segments. During NIPS

as well as phosphorylcholine copolymer [316]. Dur- process, hydrophilic segments were expected to segregate

ing the phase-inversion process for membrane fab- at the membrane surface controlled by the self-assembly

rication, surface segregation of zwitterionic segments of amphiphilic copolymers and the covalently binding

was spontaneously accomplished, generating zwitteri- non-polar hydrophobic segments were dragged onto mem-

onic brushes on membrane surface and pore surface to brane surfaces spontaneously by hydrophilic segments via

Fig. 35. The tentative illustration for dual roles of Pluronic F127 in the membrane formation process. (a) The self-assembly polymers lead to three existing

forms of Pluronic F127 in a homogeneous casting solution. (b) Immersing the ﬁlm in a water bath leads to phase separation and the formation of ordered

structure and pores within membrane.

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1699

structures and hydrophobic epicuticular waxes, inspired

by the surface features of lotus leaves (or some other plant

leaves and epidermis), confers a high water contact angle or

a small sliding angle, exhibiting superhydrophobic or low-

adhesion functions [347]. For the underwater oleophobic or

hydrophilic self-cleaning surfaces, the cooperation of phys-

ical heterogeneity and high hydration energy moieties,

inspired by the hydrated skin of marine organisms, confers

a high underwater oil contact angle to prevent oil-fouling

[348]. Due to the special properties of these self-cleaning

surfaces, such as anti-contamination and non-wetting, they

can be applied in many situations. A revolution in self-

cleaning membrane can be further anticipated.

3.4.1.1. Fabrication of membranes via incorporating low

surface energy moieties. Surface micro- and nanoscale geo-

metrical structures and low surface energy are the two

most important factors for a hydrophobic or oleophobic

Fig. 36. The tentative illustration of forced surface segregation process

during the membrane formation process. self-cleaning membrane [349]. The methods to make self-

cleaning membrane surface can be based on two strategies:

one is making a rough surface from low surface energy

“forced surface segregation” (Fig. 36). Long-term stability

materials, the other is modifying a rough surface with

of surface of the low surface energy segments presented

materials of low surface energy [350].

on membrane surfaces was also expected by the inherent

Design and fabrication of these bioinspired superhy-

self-healing capability of surface segregation methods.

drophobic membranes via electrospinning have become

an increasingly hot research topic [351]. Electrospinning

3.3.4. Challenges and shortcomings

is a versatile method of producing rough surfaces from

The formations of natural prototypes dramatically

low surface energy materials owing to the rough-

enrich the toolbox of artiﬁcial material synthesis. Extract-

ness (hierarchically textured surfaces with micro- or

ing fundamental ideas and principles from natural material

nanostructures) introduced during the spinning process

formation and then performing an imitating process is

[352,353]. One length scale of roughness is attributed

a smart strategy to construct similar physical/chemical

to the small diameters of the ﬁbers combined with

structures with organisms. Nevertheless, the complex and

hydrophobic polymers (similar with the micro-ﬁbers found

precise regulation of the material formation process by

in the ramee rear leaf in Fig. 11d), and essential to

organisms is hard to completely understand and imitate,

the superhydrophobicity of ﬁbrous membranes. Several

which indicates the development directions for the future

approaches have been reported for combining materi-

research. The challenges and shortcomings of membrane-

als of low surface energy with high surface roughness,

fabrication methods imitating the formations of natural

such as electrospinning poly(styrene-b-dimethylsiloxane)

prototypes were listed in Table 3.

block copolymers blended with homopolymer polystyrene

(PS-b-PDMS/PS) [354] and poly(3-phenyl-3,4-dihydro-2H-

3.4. Based on functions of natural prototypes 1,3-benzoxazine) blended with PAN [355]. Hardman et al.

[356] reported an in situ methodology for the produc-

3.4.1. Based on self-cleaning tion of superhydrophobic ﬁber mats by electrospinning

Self-cleaning surfaces can be classiﬁed as hydrophobic polystyrene containing ﬂuoroalkyl end-capped polymer

surfaces or hydrophilic (underwater oleophobic) surfaces. additives. Free surface segregation of such additives to

For the hydrophobic or oleophobic self-cleaning surfaces, polymer–air interface would endow ﬁbers with low surface

the cooperation of the multiscale surface geometrical energy, ﬂuorine-rich, superhydrophobic features. Inspired

Table 3

Challenges and shortcomings of membrane-fabrication methods imitating the formations of natural prototypes.

Membrane-fabrication Challenges and shortcomings

methods

Biomimetic Controllable regulation of nanoparticle morphology and surface composition within polymer matrix

mineralization In-depth analysis of mineralization reaction thermodynamics and kinetics with different inorganic precursors

and organic inducers

Biomimetic adhesion Unambiguous elucidation of formation mechanism and structure of PDA with convincing experimental

evidences

Long-term stability of PDA coating under extreme working environments

BCP self-assembly Facile synthesis of well-deﬁned block copolymers for rationally controlling the phase separation process

Precise control of defect-free self-assembly process and pore size/morphology

Surface segregation Synergistic control of the thermodynamics, kinetics, for selective surface segregation

Manipulating multiple interactions for hierarchical structure creation

1700 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

Fig. 37. (a) SEM image of an electrospun PANI/PS composite ﬁbrous membrane with lotus-leaf-like structure. (b) Magniﬁed view of a single sub-microsphere

from (a).

by biological superhydrophobic surfaces with the hierar- second level of roughness (associated with the beads) were

chical surface roughness on at least two different length found in the poly(caprolactone) (PCL) ﬁbrous membranes.

scales, a ﬁner-scale structure is needed to introduce a sec- The extremely low surface free energy of the coating

ond level of roughness. Many artiﬁcial superhydrophobic layers created by CVD yielded stable superhydrophobic-

◦

micro/nanoporous ﬁbrous membranes have been facilely ity with a contact angle of 175 . They also prepared

fabricated by creating the second level hierarchical surface double-roughened superhydrophobic ﬁbrous membrane

geometrical structure from nanohybrid systems. Nano- by decorating micrometer-scale electrospun ﬁbers with

materials, such as SiO2 nanoparticles [357–359], Al2O3 nanometer-scale pores or particles [366].

nanoparticles [360] TiO2 nanoparticles [361] and graphene Tuteja has conducted representative researches on

nanoﬂakes [361], assembled in the polymeric ﬁbers could the conjunction between re-entrant surface curvature,

change the surface morphology and chemistry, leading chemical composition and roughened texture to design

to superhydrophobicity with self-cleaning properties. Zhu the oleophobic self-cleaning fabric membranes, based on

et al. [362] fabricated an artiﬁcial composite ﬁbrous the extremely low surface energy polyhedral oligomeric

membrane from polyaniline (PANI) doped with azoben- silsesquioxane (POSS) molecules with the rigid silsesquiox-

zenesulfonic acid blended with PS via electrospinning ane cage surrounded by perﬂuoro-alkyl groups (ﬂu-

(Fig. 37). A web of nanoﬁbers with many sub-microspheres oroPOSS). A series of oleophobic membranes were

over the whole substrate was linked by many nanoknots, fabricated via a simple dip-coating and thermal anneal-

as well as the nanoscale protuberances covering each sub- ing procedure with the mixture of ﬂuoroPOSS and

microsphere. The composite ﬁbrous membrane surface PMMA, poly(ethylmeth acrylate) (PEMA), cross-linked

displayed a structural similarity to the surface of a lotus poly(ethylene glycol) diacrylate (x-PEGDA), or cross-linked

leaf with a distinct self-cleaning effect. These superhy- PDMS onto textured substrates (such as stainless steel

drophobic ﬁbrous membranes are particularly promising wire meshes), possessing re-entrant curvature on the

for ﬁltration and separation applications. Jiang et al. coarser length scale [367–370]. For example, different fab-

[363] created a series of micro/nanostructured poly(N- ric morphologies with the “beads on a string” morphology,

isopropylacrylamide) (PNIPAAm)/PS composite ﬁlms with multiple scales of roughness and high porosity could be

thermoresponsive properties via the electrospinning. The tuned by varying the concentration of the ﬂuoroPOSS

microparticles/nanoﬁbers hierarchical roughness could and PMMA blends [367]. The surfaces possessing multi-

enhance the temperature-responsive wettability switched ple scales of roughness enabled ﬁber membranes to confer

between superhydrophilicity and superhydrophobicity oleophobicity and superhydrophobicity at higher POSS

triggered by temperature. concentrations, as well as oleophobicity and hydrophilic-

Chemical vapor deposition, as a one-step, solvent-free ity at lower POSS concentrations. The re-entrant surface

deposition technique for surface modiﬁcation, can be used curvature, in conjunction with surface chemistry and

to introduce low surface energy features to nanoscale roughness was necessary for superoleophobicity of the

rough surfaces to produce hydrophobic self-cleaning membrane surfaces.

membrane surfaces. Jin et al. [364] demonstrated super- Self-cleaning membranes could also be constructed by

hydrophobic and superoleophobic self-cleaning nanocellu- other simple and available methods. Textile membranes

lose aerogel membranes using cellulose nanoﬁbers treated coated with thiol-ligand nanocrystals based on the inter-

with ﬂuorosilanes via CVD. The superhydrophobic and action between the VIII and IB nanocrystals and n-octadecyl

superoleophobic properties were primarily attributed to could be endowed with superhydrophobic and super-

the ﬂuorinated ﬁbrillar networks and aggregates with oleophilic properties [371]. PVDF membrane composed

structures at different length scales. Ma et al. [365] reported of linked pherical microparticles with microprotrusions

a signiﬁcant increase in the hydrophobicity of ﬁbrous mem- densely and evenly distributed on the surface could

branes by combining electrospinning and CVD. The ﬁrst be fabricated via an inert solvent-induced phase inver-

level of roughness (associated with the ﬁbers) and the sion, showing both superhydrophobic and superoleophilic

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1701

Fig. 38. (a) Temperature-controlled water/oil wetting behavior on a block copolymer-coated mesh. (b) A schematic showing reversible conformational

change of the PNIPAAm chain and the resultant surface roughness at different temperature leading to two states of wettability.

[372]. Yang et al. [373] employed nanoparticle-polymer porous metal substrates [376]. Recently, they directly cast

suspension coating to fabricate a self-cleaning stain- thermal-responsive block copolymer PMMA-b-PNIPAAm

less steel mesh membrane. Synergistic effect of the onto a steel mesh and obtained membrane with two

micro/nanoscale hierarchical structures created by SiO2 switchable states of wettability at different temperatures

nanoparticles and the hydrophilic–oleophobic groups of (Fig. 38a) [377]. PMMA-b-PNIPAAm self-assembled into

poly(diallyldimethylammonium chloride) (PDDA)-sodium a lamellar structure with PNIPAAm domains between

perﬂuorooctanoate (PFO) enabled the spray-coated mesh the hard walls of PMMA on a nanometer scale. A dis-

membrane to exhibit superhydrophilic–superoleophobic continuous conformational change of the PNIPAAm

property. In our recent study, amphiphilic self-cleaning chain determines the surface roughness around the

membrane surfaces, possessing mixed domains of mosaic lower critical solution temperature and the coopera-

hydrophilic and low surface energy characteristics, tion between PNIPAAm and PMMA domains, imparted

were constructed via the surface grafting perﬂuoroalkyl the ﬁlm with reversible switching between wettability

molecules [374,375] and forced surface segregating of low states of hydrophilicity/oleophobicity and hydropho-

surface energy amphiphilic copolymers [128,343,346]. The bicity/oleophilicity (Fig. 38b). Feng and coworkers also

low surface energy microdomains on the membrane sur- underwater superoleophobic chitosan-coated meshes

face, constructed with ﬂuorine-based polymers, were to from cross-linked chitosan network, and the stability of

minimize the intermolecular interactions between oil and chitosan-coated meshes could be improved by modifying

the membrane surface. The hydrophilic domains were to the CS coating by fully cross-linking, reduction, and PVA

bind water molecules and to generate hydration layer to addition [378].

form an oil/water/solid interface with oleophobicity. Most recently, Jin and coworkers reported under-

water superoleophobic membranes from PMAPS-g-PVDF

and PAA-g-PVDF. The superoleophobic and ultralow oil-

3.4.1.2. Fabrication of membranes via incorporating high

adhesion characteristics of PMAPS-g-PVDF membrane

hydration energy moieties. Superhydrophilic surfaces

were attributed to the higher surface energy and hydrated

immerged under water can also provide oleophobicity

behavior of grafted zwitterionic PMAPS chains in water.

and self-cleaning behavior. The high hydration states of

The extended conformation of hydrated PMAPS chains

hydrophilic moieties on membrane surfaces trap high ratio

would generate tightly bound hydration layer and pro-

of water molecules around by electrostatic or hydrogen

mote oil droplets rolling off from membrane surface

bond interaction, which effectively blocks the access of the

[109]. The underwater superoleophobic wetting behav-

oils to membrane surfaces. The methods to make under-

ior of PAA-g-PVDF membranes were determined by both

water oleophobic or hydrophilic self-cleaning membranes

the hierarchical micro/nanoscale structure and hydrophilic

focus on incorporating high hydration energy moieties

nature of PAA chains. The micro/nanoscale spherical

onto membrane surfaces.

microparticles on the membrane surface was generated

Jiang and coworkers depicted underwater self-

from PAA-g-PVDF micelle aggregates during the salt-

cleaning superoleophobic membranes with special

induced phase-inversion approach: in the coagulation step,

micro/nanoscale hierarchical structures. Underwater

rapid solvent exchange promoted the crystallization of

superoleophobic membranes were developed from

NaCl out from the water and the nascent small crystal seeds

polyacrylamide hydrogel-coated mesh membranes with

acted as accumulation points to aggregate surrounding

rough nanostructured hydrogel coatings and microscale

1702 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

PAA-g-PVDF micelles. It was proved that greater roughness The diversity and complexity of non-traditional water

could enhance anti-wetting behavior of underwater oils on will bring more difﬁculties to membrane processes for

membrane surfaces [379]. water and waste water treatment. Membrane fouling,

regarded as the bottleneck problem in widespread imple-

3.4.2. Challenges and shortcomings

mentation of water treatment membrane, always leads

The popular research topic of special wetting behavior

to drastic ﬂux decline, frequent cleaning, increased oper-

has provided valuable guidelines for self-cleaning mem-

ating cost and energy consumption. Fouling often occurs

brane design. However, the crucial challenges must be

when water containing typical foulants (e.g., particle,

kept in mind. For hydrophobic (or oleophobic) self-cleaning

colloidal, macromolecule, hydrocarbon mixtures, natural

membrane, ﬂuorinated moieties were employed in most

organic matter and microorganism) is ﬁltered through

cases to lower the surface energy. However, the synthesis

a membrane. These foulants can deposit and adsorb on

and use of ﬂuorinated moieties may raise the possibility of

the membrane surface or pore walls, which strongly

ﬂuorine contamination in ecosystem, which always cause

reduces water ﬂux and affects separation performance of

harmful effects on living organic bodies. Therefore, envi-

membranes. Biomimetic and bioinspired strategies have

ronmentally benign strategies for self-cleaning purpose

provided new insights into designing and developing

will be highly appreciated. For hydrophilic (or underwa-

various antifouling membranes for improved separation

ter oleophobic) self-cleaning membrane, the durability of performance.

surface hydrophilic feature is largely concerned. The struc-

Considering that oil wastewater generated by hydrocar-

tural evolution of hydrophilic layer under harsh condition,

bon processing, metallurgy, oil-spill mixtures, etc., always

such as high temperature, high salinity and high alka-

cause terrible environmental pollution, it is necessary to

linity/acidity, has not been well investigated. Combined

develop antifouling membranes to remove oil from water

strategies based on multiple interactions will be high-

efﬁciently. Inspired by the versatile anchoring ability of

lighted for enhancing the stability.

mussel adhesive proteins, hydrophilic PDA has been used

to impart oil fouling resistance to MF, UF, NF and RO

4. Applications of biomimetic and bioinspired

membranes [220–222,380–382]. Freeman et al. [220,382]

membranes

deposited PDA on PSf support polyester membranes in

pressure retarded osmosis and studied the antifouling abil-

From the above description, it can be deduced that

ity of PDA modiﬁed membranes in oil/water ﬁltration. The

the biomimetic and bioinspired membranes have no mys-

membranes modiﬁed with PDA at all dopamine concen-

tery but are made through a novel strategy or idea.

trations, deposition times, and alkaline pH values were

The application ﬁelds of the biomimetic and bioinspired

signiﬁcantly more resistant to oil fouling than uncoated

membranes are thus identical to those of the existing syn-

membranes during emulsiﬁed oil–water ﬁltration. PDA

thetic membranes. Due to the hierarchical structures, as

also enables a variety of reactions with functional organic

well as controlled selective transport, stability/resistance,

molecules, such as Michael addition or Schiff base reactions

the biomimetic and bioinspired membranes have strut

between catechols and amines [44]. Amine-terminated

their stuff in sustainable resources, environment, energy

poly(ethylene glycol) (PEG-NH2) could be anchored onto

aspects. Due to the length limitation, herein, we only

PDA modiﬁed MF, UF, NF, and RO membranes to improve

present the following three important application ﬁelds.

fouling resistance, taking advantage of the well-known

fouling resistance properties of PEG [221,380,381]. PDA

4.1. Water treatment

and PDA-g-PEG modiﬁed PTFE MF membranes had 20%

Water treatment is a worldwide challenge because of and 56% higher ﬂux, respectively, than unmodiﬁed mem-

the increasing amount of wastewater from both industrial branes after 1 h of emulsiﬁed oil/water ﬁltration. PDA

and municipal that has given rise to environmental issues and PDA-g-PEG modiﬁed PES UF membranes increased

of global concern. Water purification and wastewater oil emulsion filtration flux approximately 35% compared

treatment can be for discharge or to enable further reuse to their unmodiﬁed counterpart after 1 h of ﬁltration.

or recycling. The overarching goal for the future of water Both RO and NF membranes with PDA-modiﬁed mem-

reuse is to capture water directly from non-traditional brane exhibited approximately 30–50% higher ﬂux than

sources such as industrial or municipal wastewaters, and the unmodiﬁed membranes after one day of oil emul-

provide access to clean water [314]. sion ﬁltration and the PDA-g-PEG modiﬁed membrane

Membrane technology for producing high quality displayed no ﬂux decline during the ﬁltration. Short-term

water from non-traditional water (such as agricultural, BSA adhesion reduction was also observed on the PDA-

municipal, and industrial wastewater, brackish water g-PEG modiﬁed membranes in all cases and the general

and seawater) has been widely approved in recent years. trend of BSA adhesion was reduced with the increase of

The application of membranes has led to an excellent PEG graft molecular weight [221]. However, Freeman et al.

efﬂuent quality to ensure water scarcity, freshwater sup- [222] also demonstrated that PDA and PDA-g-PEG coat-

plies and beneﬁcial reuse. Conventional pressure-driven ings might not effectively control long-term membrane

membrane processes such as MF, UF, NF and RO have been fouling.

actively employed for municipal and industrial wastewater Conventional oil removing membranes are easily fouled

treatments. Particular attention has also focused on the uti- or even blocked up by oils because of their intrinsic

lization of next-generation high-performance biomimetic oleophilic property. Inspired by the self-cleaning lotus

and bioinspired membranes in water treatment. leaves with special wettability, the wetting/antiwetting

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1703

Fig. 39. Separation of oil-in-water and water-in-oil emulsions. (a) Separation apparatus with a 50:50 (v:v) hexadecane-in-water emulsion above the

membrane. Inset, hexadecane droplet on a surface spin-coated with ﬂuorodecyl POSS and x-PEGDA blend, submerged in water containing a dissolved

nonionic surfactant. (b) Water-rich permeate passed through the membrane whereas hexadecane-rich retentate was retained. (c) Separation apparatus

with a 30:70 (v:v) water-in-hexadecane emulsion above the membrane. Inset, hexadecane droplet on a surface spin-coated with ﬂuorodecyl POSS and x-

PEGDA blend, submerged in water containing dissolved PS80. (d) Water-rich permeate passed through the membrane whereas hexadecane-rich retentate

was retained. Water is dyed blue and hexadecane is dyed red.

behavior of oil droplets is very important to the design PDDA-PFO/SiO2 prepared by Yang et al. also exhibited

of membranes with low oil fouling. Tuteja et al. [368] desirable water permeation and oil repellency behav-

successfully applied oleophobic self-cleaning membranes iors, and could selectively separate water from oil–water

with re-entrant texture and amphiphilic characteristics mixtures with the features of good antifouling and easy-

to oil–water separation. The superhydrophilic and super- recycling [373]. Receiving beneﬁts from the development

oleophobic mesh membranes spin-coated with ﬂuorodecyl of bio-inspired special wettability, several superhydropho-

POSS and x-PEGDA blend could selectively separate water bic and superoleophilic membranes were also applied

from various oil–water mixtures solely driven by grav- effectively in the separation of oil and water [371,372].

ity. Membrane oleophobicity under water was the pivotal Ding et al. [357,358,360] realized high-throughput sep-

factor for the separation of oil-in-water emulsions. The aration of oil–water mixtures by employing ﬂuorinated

PEGDA chains of amphiphilic surfaces would reconﬁgure hybrid superhydrophobic and superoleophilic electrospun

when water phase of the emulsion contacted the mem- nanoﬁbers. When the oil–water mixture or emulsions

brane, allowing water passing through the membrane were poured onto these membranes, oils would quickly

while the hexadecane droplets retained above the mem- spread and permeate through the membranes with water

brane (Fig. 39b). Membrane oleophobicity, both in air and still remaining on the membrane surface. A promising

−2 −1

under water, was crucial for separating water-in-oil emul- ﬂux of 3311 L m h and high separation efﬁciency was

sions. The PEGDA chains of amphiphilic surfaces started reported [358]. Inspired by the hierarchical structures

to reconfigure when water droplets within the emul- of fish scale that enabled fish to keep their body clean

sion contacted the membrane, with hexadecane phase in oil-polluted water, underwater superoleophobic poly-

retained above the membrane while the water droplets acrylamide hydrogel-coated [376] and chitosan-coated

passed through the membrane (Fig. 39d). These mem- [378] mesh membranes has been used successfully in

branes could separate different oil–water emulsions with gravity-driven separation process of oil–water mixture

high separation efﬁciency. In both case, the permeate con- and exhibited separation efﬁciency higher than 99% for

∼

tained only 0.1 wt% hexadecane, whereas the retentate diverse oil. In water, the hydrophilic coatings could absorb

∼

contained only 0.1 wt% water. Furthermore, superoleo- water to its balance state. When the hydrogel coatings con-

phobic mesh membranes spin-coated with ﬂuorodecyl tacted with the oil droplets, water could be trapped in the

POSS and x-PDMS blend could also removes >99% of rough nanostructures and the new oil–water–solid com-

the emulsiﬁed oil droplets from various oil/water mix- posite interface showed superoleophobic property because

tures triggered by electric ﬁeld [369]. The low solid trapped water molecules would greatly decrease the con-

surface energy and the re-entrant texture of the mem- tact area between oil droplet and membrane surface

brane allowed it to support both water and hexadecane with discontinuous triple-phase contact line. The group of

in the Cassie–Baxter state (superomniphobic) without an Jin also proposed underwater superoleophobic polyelec-

electric ﬁeld. After applying an electric ﬁeld, the polar trolyte grafted PVDF membranes could effectively separate

water in the Cassie–Baxter state under gravity would tran- surfactant-free oil-in-water emulsion with high separa-

−2 −1

sit to the Wenzel state. Once the applied pressure was tion efﬁciency (>99.99%) and high ﬂux (>1500 L m h ,

larger than the maximum pressure that liquid–air interface 0.01 MPs) [109,379].

could withstand, water could permeate through the mem- Our group fabricated amphiphilic self-cleaning mem-

brane while the oil was retained. The superhydrophilic branes with compositional heterogeneity combining the

and superoleophobic nanocomposite-coated membranes fouling release property of low surface energy component

1704 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

Fig. 40. Tentative illustration of the ﬂux-decline resistant mechanism of amphiphilic membranes with compositional heterogeneity.

with the fouling resistant property of hydrophilic com- membranes with superhydrophobicity due to the hier-

ponents on the surface and applied these membranes to archical structures, which were desirable for membrane

oil/water emulsion separation [128,343,346,375]. Mem- distillation application [384]. The considerable water

brane fouling could be exquisitely suppressed: permeation ﬂux enhancement (2–3 times higher than commercial

ﬂuxdecline was decreased to an ultralow level (the mini- PVDF membrane) was attributed to the open surface pore

−1

mal value is less than 3.4%) and permeation ﬂux recovery structure, and stable low conductivity (<5 ␮s cm ) was

after simple hydraulic washing was retained at nearly attributed to the lack of pathways for NaCl to permeate

100%. During the dynamic ﬁltration process, the fouling through the superhydrophobic membrane. Mansouri

release property of low surface energy microdomains pre- et al. [385] reported the robust antifouling property of

vented coalescence, migration, and spreading of the holistic superhydrophobic ﬂuorosilanized TiO2 nanocomposite

hydrophobic oil droplets, remarkably reducing or even PVDF membranes toward different concentrations of both

eliminating the reversible ﬂux decline. The hydrophilic NaCl and humic acid solutions, which indicated the long

domains further improved the antifouling property by term antifouling performance in the complicated real sea

generating compact hydration layer and resisting the non- water environment.

speciﬁc interaction between the foulants and membrane For the effective treatment of various industrial

surface. Moderate shear force easily swept the oil droplets wastewater, incorporating nonfouling polymer brushes

from surface and pushed them back to the bulk feed solu- onto membrane surfaces is a promising approach to repel

tion (Fig. 40). different kinds of foulants: not only hydrocarbons but also

Bioinspired superhydrophobic self-cleaning mem- microorganisms, biomacromolecules and colloidals. Typi-

branes with micro/nanoscale hierarchical structures that cally, membrane surfaces modiﬁed with phospholipid-like

exhibit extreme water repellence could be also applied zwitterionic materials have been applied to fend off cells,

for membrane distillation. Wang et al. [383] applied proteins, or other organic compounds from adhering onto

electrospun PS micro/nano-ﬁbrous membranes with the the surface. The zwitterionized PSf membrane derived from

similar micro/nanoscale hierarchical structures of lotus PSf/PDMAEMA-b-PSf-b-PDMAEMA blend membranes was

leaf and silver ragwort leaf for desalination via direct found to be almost free of cell adhesion [147]. The PVDF-

contact membrane distillation. The high superhydropho- g-PCBMA and PVDF-g-PSBMA membranes derived from

◦

bicity (>150 ) avoided membrane wetting and ensured PVDF/PVDF-g-PDMAEMA blend membranes exhibited no

high liquid entry pressure for stable low permeate con- proteins deposition [145]. The PVDF membrane coated

ductivity. The reasonably high porosity (∼70%) enhanced with amphiphilic PPO-b-PSBMA was shown to effectively

vapor permeation, which was about 4–5 times higher resist nonspeciﬁc protein surface adsorption during the

than commercial PVDF membrane. By using combined dynamic ﬁltration process, with minimum irreversible ﬂux

fabrication method, the electrospun nanoﬁbers modiﬁed decline ratio of 4.1% [386]. The zwitterionic colloid parti-

with silver nanoparticle and 1-dodecanethiol using poly- cles coated PSf membrane was reported to have satisfying

dopamine as the “bio-glue” could endow the nanoﬁber antifouling property and stable nanoﬁltration performance

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1705

when challenged with humic acid and BSA in a 30 h of water or brackish water desalination. Recently, several

ﬁltration test [142]. To obtain durable antifouling proper- approach for fabricating AQP-based composite membranes

ties and separation performance of membranes that ensure with compatible NaCl rejection were reported. Chung et al.

the stable efﬂuent quality in water treatment processes [162] cross-linked ruptured AQP incorporated vesicles with

for long-term operation, membranes with self-healable acrylate-functionalized polycarbonate membrane support

antifouling properties have incited broad attention in to reduce the number of uncovered pores to an insigniﬁ-

recent years. Natural superhydrophobic plant leaves has cant level and increased the NaCl rejection to above 98.5%.

the ability to self-heal a damaged voids within the epicu- They also applied AQP-embedded vesicular membrane sta-

ticular wax layer by the rearrangement of wax molecules bilized through an optimized layer-by-layer PDA-histidine

into layered structures, which ensures the durability of the coating in speciﬁc forward osmosis testing mode using

nonwettability over their whole lifetime. Membranes fabri- 6000 ppm NaCl as the feed and 0.8 M sucrose as the draw

cated via the surface segregation of amphiphilic copolymer solute and reported high salt retention of 91.8% [388].

also have the advantages of providing self-healing capac- Tang et al. [165] found that 1,2-dioleoyl-sn-glycero-3-

ity, because the damaged antifouling brush layers would phosphocholine-based proteoliposomes displayed excel-

eventually be fully displaced by the surface segregation lent osmotic water ﬂux and NaCl reﬂection and obtained

agents from the membrane bulk and provide almost com- good NaCl rejection (∼97%) and high water permeabil-

−2 −1 −1

plete recovery of antifouling properties. The ﬂux recovery ity (4.0 L m h bar ) by incorporated AQP incorporated

ratio of the surface segregation membrane with the zwit- vesicles in well-established interfacial polymerization.

terionic SBMA content of 5.8 mol% was reported to be They also suggested a perspective design criteria for

retained at 92% even after three cycles of protein ultra- AQP-based composite membranes in the application of

ﬁltration [129]. The ﬂux recovery ratio of the surface desalination [390]: AQP-containing proteoliposomes were

segregation membrane with the near-surface coverage responsible for providing preferential water paths in the

of Pluronic F127 of 62 mol% exhibited ﬂux recovery as ion rejection layer (Fig. 41a) and fused AQP-containing

high as 90% within three repetitive operations of protein lipid bilayers were in charge of NaCl rejection (Fig. 41b).

ultraﬁltration [334]. Especially, low surface free energy Sophisticated combination of lipid bilayer and proteolipo-

membrane surfaces generated from forced surface segrega- somes embedded matrix were predicted to achieve both

tion of ﬂuorine-containing copolymers could also maintain high water permeability and high salt rejection (Fig. 41c).

the superior antifouling performance for oily foulants after Despite the notable achievements in AQPs based mem-

several cycles of ultraﬁltration operation [128,343,346]. branes, there are still limitations to scale up and large scale

In many water or wastewater treatment applications, employment due to the necessity of highly specialized and

metal ion, protein, bacterial and some other contam- prohibitively expensive nanofabrication techniques [153].

inants existed in water or wastewater were removed Moreover, the stability of AQP-containing proteoliposomes

mainly by the sieving mechanism based on the size of the under variable and extreme seawater condition must be

contaminants and the membrane pore size. Nanoporous taken into consideration. As alternative, carbon nanotubes

membranes are expected to be very useful to perform (CNT) are proved to exhibit a fast mass transport than

not only good resolution but also high throughput [3]. that calculated from continuum hydrodynamics models,

Inspired from the excellent selective transport attribute like aquaporin water transport [393]. The potential appli-

of cell membrane, several strategies have been developed cations of CNT as the selective layer at the surface of a

for fabricating biomimetic and bioinspired membranes for membrane for water treatment can be predicted with an

efﬁcient water treatment. array of high ﬂux molecular channel.

Nanoporous biomimetic membrane containing AQPs Membranes with ultrahigh density of uniform

is very promising for water puriﬁcation. The exceptional molecular-size pores easily produced in technical scale

selectivity and permeability of AQPs ensure them a poten- can bring a breakthrough in membrane-based water

tial candidate to design high-performance membranes treatment [297]. The self-assembly of block polymers

for desalination. Kumar et al. [161] ﬁrst reported that shows superiority in producing nanoporous membranes

AQP-incorporated triblock copolymer membranes could with narrow pore-size distributions, high porosity and

lead to more controllable, productive and sustainable the sharp molecular weight cut-off. On the basis of the

water treatment membranes with the variable levels of above features, many nanoporous membranes have been

permeability obtained with different concentrations of fabricated via the self-assembly of block copolymers and

AQPs. Permeability peaked at a protein-to-polymer ratio exhibited relative high ﬂuxes compare with commercial

of 1:50 with the permeability 3000 times greater than membranes, as summarized in Table 4. Such membranes

the pure polymer. Systematic researches have been car- possess great potentials for competitive macromolecular

ried out on active AQP based composite membranes, separation platform, because the monodispersed pores

which exhibited competitive water permeability and guarantee superior selectivity, high void fraction allows

enhanced ion rejections for existing RO, FO or NF system for high ﬂuxes and the smooth surfaces deter fouling [264].

[160,162–165,387–392]. The outstanding performance of The work by Stamm et al. was one of the speciﬁc application

AQP based NF membrane could offer the overall water example. The nanoporous PS-b-P4VP membrane derived

−2 −1 −1

ﬂux of 36.6 L m h bar with a MgCl2 rejection of from the self-assembly of PS-b-P4VP/HABA supramolec-

95% (1 bar) [391]. Usually, AQP-based composite mem- ular complexes contained monodisperse pore radius of

14 −2

branes showed exceptional multivalent ion rejections but 12.3 nm and high pore density of 2.43 × 10 pores m ,

lower NaCl rejection, which limited the application in sea which determined the high Congo red dye rejection

1706 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

Fig. 41. Conceptual designs of AQP-based composite biomimetic membranes.

−2 −1 −1

(>98%), fast pure water ﬂux (>600 L m h bar ). Fur- green, energy-saving, and high-efﬁcient features, mem-

ther quaternization and zwitterionization reactions on a brane technology has been widely applied in clean energy

P4VP moiety enhanced the antibacterial and antifouling production, and exhibits noteworthy technical and eco-

properties of membranes [144]. However, there is still a nomic advantages over some conventional technologies.

long way to go to bring the pore sizes down to molecular Furthermore, biomimetic and bioinspired membranes

dimensions for small-molecule separations [3] and to have found their way in broad applications and been show-

create long-range ordered, robust and highly selective ing promising prospects.

nanochannels for large-scale production.

4.2.1. Fuel cell

4.2. Clean energy Fuel cell is an electrochemical device which employs

the reaction between renewable fuel (hydrogen, alcohol,

The development of clean energy has attracted exten- and other hydrocarbon compounds) and oxidant (oxygen)

sive concerns due to the increasing demands for energy to transform the chemical energy of fuel to electric energy

and the deteriorating environmental problems. Due to the without going through heat engine process. In many types

Table 4

Summary of selective nanochannels of membranes based on block copolymer self-assembly.

a b −2 −1 −1

Assemblies Effective pore diameter (nm) Superstructure morphology Water permeability (L m h bar ) Reference

PS-b-PMMA ∼15 C ∼450 [258]

PS-b-PMMA ∼17 C ∼200 [251]

PS-b-PI-b-PLA ∼22 C ∼165 [267]

PS-b-P4VP ∼8 C ∼40 [295]

PS-b-P4VP ∼19 C ∼850 [296,297]

PS-b-P4VP ∼50 C ∼600 [298]

PS-b-P4VP ∼25, 38 C ∼450, 625 [311]

PS-b-PMMA ∼1–2 S ∼37 [304]

PI-b-PS-b-P4VP ∼16–36 C ∼150–850 [300,313]

PS-b-PEO ∼20–30 C ∼800 [312]

PS-b-P2VP ∼8–25 G ∼100–300 [303]

PS-b-P4VP ∼100 C ∼3200 [299]

PS-b-P4VP ∼25 C ∼600 [144]

C: vertically oriented cylindrical pores near the top surface, G: gyroid pores near the top surface, S: pores origin from close-packed spherical cores.

Pure water ﬂux under neutral pH condition.

Asymmetric pore morphology in the overall structure.

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1707

of fuel cells, the ion exchange membrane is a key compo- phases as supporting substrate. The membrane mor-

nent determining the fuel cell performance for its functions phology and the size of hydrophilic channel can be

of ion conduction. Meanwhile, the membrane plays a piv- manipulated expediently by controlling the molecular

otal role in preventing the diffusion of fuel from the anode weight, hydrophilicity/hydrophobicity, and rigidity of each

to the cathode, which otherwise will drastically reduce the segment [306,397]. Balsara et al. [397] fabricated PEMs

fuel cell performance due to the mixed potential effect employing poly(styrene sulfonate)-b-poly(methyl buty-

and catalyst poisoning [394,395]. Different biomimetic and lene) (PSS-b-PMB) with the width of dry hydrophilic phases

bioinspired strategies have been adopted to promote ion ranging from 2.5 nm to 39 nm. It was revealed that the

conduction and inhibit fuel diffusion. PEMs with diameters of hydrophilic phases less than 5 nm,

Xu et al. [202] and Liu et al. [201] utilized quaternized possessed higher water uptake and proton conductivity

polymer to induce the mineralization of silica precursor at high temperature compared with Naﬁon membrane

for the fabrication of hybrid anion exchange membrane. and the membranes with larger hydrophilic phases. For

After hybridization, the thermal stability and mechani- instance, with the temperature arising from 298 K to 363 K,

cal strength of membrane were improved owing to the the water uptake increased from 72.5 wt.% to 74.9 wt.%,

−1

stable structure of inorganic component and the interac- and the proton conductivity increased from 11 S m to

−1

tions between organic and inorganic phases, beneﬁting the 19 S m for membrane with hydrophilic phase of about

practical application in fuel cell. The methanol crossover 5 nm. By contrast, the membrane with 7 nm hydrophilic

−10 2 −1 −11 2 −1

decreased from 4.1 × 10 m s to 8.45 × 10 m s phase exhibited a decreased water uptake from 52.5 wt.%

due to the more tortuous methanol-transport pathways to 30.5 wt.%, and a decreased proton conductivity from

−1 −1

and the decreased free volume, which increased the dif- 8 S m to 6 S m under the same experimental condi-

fusion resistance of methanol [201]. tions. This phenomenon can be explained by the capillary

A promising type of ion exchange membrane is condensation in conﬁned spaces which suppressed the

microphase-separated membrane, which can form ion- evaporation of water. The desirable results provided a

cluster channels beneﬁting the rapid transport of ions. promising prospect for the application of PEMs at high tem-

However, the relatively high fuel permeability restricts perature.

its application [394,395]. Among the various methods to Besides forming ordered channels by self-assembly of

decreasing fuel permeability, coating a fuel-barrier layer block copolymers, several top-down approaches have also

has been demonstrated as a successful example because been explored to construct ordered channels for ion con-

of its facile manipulation and high efﬁciency [225]. The duction, in which porous substrates were grafted [398,399]

barrier layer can block the ion-rich hydrophilic domains or inﬁltrated [400] with polyelectrolytes for ion conduc-

in microphase-separated membranes, and then inhibit the tion. Moghaddam et al. [399] fabricated a silica membrane

crossover of fuel [395]. Nevertheless, the ion conductiv- with pores of 5–7 nm, and grafted sulfonic acid groups onto

ity may decrease if the coating layer is non-conductive the inner surface for proton conduction. The maximum

−1

and thick [394]. Therefore, constructing a fuel barrier layer conductivity of the silica membrane can reach 11 S m . To

with ion conduction capability and low thickness is desir- maintain the high conductivity at low humidity, an ultra-

able. Inspired by the bioadhesion phenomenon, Wang et al. thin silica layer with the thickness and pore size of ∼2 nm

[225] modiﬁed Naﬁon membrane (the most commonly was deposited at the mouths of the nanopores. The inner

utilized cation exchange membrane with microphase- surface was also modiﬁed with sulfonic acid groups to

separated structure) surface with PDA. The cross-linking conduct proton. The smaller pore size inhibited the water

structure of PDA layer can block the ion-cluster channels, release when being used in fuel cell. As a result, the pro-

and suppress the swelling of Naﬁon membrane. In addi- ton conductivity of the two-layer silica membrane could

tion, the low hydrophilicity of PDA was unfavorable for the maintain constant until the humidity was below 20%, while

solution of methanol on membrane surface. As a result, the proton conductivity of mono-layer silica membrane

the methanol crossover of the membranes decreased began to decline when the humidity decreased to 50–60%.

−10 2 −1 −10 2 −1

from 3.14 × 10 m s to about 0.65 × 10 m s . Fur- Moreover, the proton conductivity of the two-layer silica

thermore, the ultrathin thickness of PDA layer and the membrane was two to three orders of magnitude higher

numerous proton conducting groups (amino, imino and than that of Naﬁon at low humidity. Due to the rigidity

catechol groups) in PDA layer endowed the Naﬁon mem- and solvent resistance of porous substrates, the swelling of

brane with slight sacriﬁce of proton conductivity. the polyelectrolytes in pores can be suppressed effectively,

In recent years, the block copolymers comprising of which can otherwise lead to high fuel crossover. Moreover,

hydrophilic and hydrophobic segments have been under the membrane can exhibit favorable durability in practical

intense study for ion exchange membrane because they application.

are easy to form ordered ion-cluster channels resembling

biological nanopores/nanochannels and achieve high ion 4.2.2. Alcohol fuel

conductivity. Various block copolymers with sulfonic acid In recent years, alcohol fuel (mainly including methanol,

and quaternary ammonium groups have been prepared ethanol, propanol and butanol) produced from biomass

for proton exchange membranes (PEMs) [306,396,397] and has gained keen interest as an environmental friendly and

anion exchange membranes [246], respectively. Through renewable alternative for fossil energy. During the produc-

assembly, the hydrophilic segment form ordered channels tion process by fermentation, the produced alcohol must

with connected sulfonic acid or quaternary ammonium be removed timely due to its inhibitory effect on the activ-

groups while the hydrophobic segments form high-stable ity of yeast [242]. Pervaporation is a suitable approach to

1708 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

achieve the high-efﬁcient removal of alcohol in continuous increasing molecular weight of block copolymers led to

fermentation because it is operation simple, energy-saving, larger domain spacing, which was favorable for enhancing

poison-free for microorganism and easy to couple with the permselectivity of ethanol [242]. The solvent [244] and

reaction [242,401]. Moreover, water is also produced in the mass ratio of blocks [243] had signiﬁcant inﬂuence on the

fermentation process, which will exist in the crude alcohol self-assembled morphology (such as spherical, cylindrical

product and must be removed to obtain the high-puriﬁed and lamellar morphologies). It was revealed that the

alcohol. Pervaporation is also suitable for the separation continuous cylindrical morphology exhibited the best

of azeotropic mixtures (such as water–alcohol mixture), separation performance. When tested the membrane with

because it is not restricted by vapor–liquid equilibrium. fermentation broth as the feed solution, an enrichment of

Both alcohol- and water-permselective pervaporation ethanol from 8 wt.% to 40 wt.% was acquired [243].

membranes can be used in the production of alcohol fuel.

Presently, different biomimetic and bioinspired strategies

have been adopted to fabricate membranes with high sepa- 4.2.3. Clean gasoline

ration performance so as to strengthen the competitiveness For the foreseeable future, fossil fuels will continue to

of pervaporation process. play an important role in the generation of heat and power

In membrane separation processes, permeation ﬂux in daily life and industrial production. Consequently, the

represents the treatment capacity of membrane, which cleaning of fossil fuels is an important strategy to reduce

means high permeation ﬂux can reduce the required environmental pollution. The sulfur compound in gaso-

membrane area and hence lower the membrane cost line is one of the main sources of atmosphere pollution

in the investment. It is well accepted that the mem- and acid rain, which can also poison the catalysts for vehi-

brane thickness has a direct inﬂuence on the permeation cle exhaust gas converting [196]. Therefore, the sulfur

ﬂux of pervaporation membrane: the thinner membrane content in gasoline must be controlled strictly. In recent

can shorten the diffusion path of permeate molecules years, pervaporation desulfurization has attracted increas-

and then increase the membrane permeation ﬂux [402]. ing attention due to its advantages over conventional

Accordingly, composite membranes consisting of a thin hydrodesulfurization process, including higher selectivity,

dense separation layer and a thick porous support layer lower operating and energy costs, facile scale-up, main-

formed by different materials are generally adopted in taining the octane number, as well as without hydrogen

industrial-scale applications. In order to further decrease source and coproduct of H2S gas [196,197,403]. Various

the thickness of separation layer, the higher stability of biomimetic and bioinspired strategies have been adopted

separation layer, as well as the higher interfacial strength to develop membrane materials with superior separation

between separation layer and support layer are demanded performance and stability.

to obtain the acceptable selectivity and lifespan. PDMS is the dominant membrane material for per-

Inspired by the multi-interaction and high-strength fea- vaporation desulfurization of gasoline owing to its good

ture of bioadhesion phenomena, various bioadhesives and processability, superior permeability as well as high afﬁn-

biomimetic adhesives including CP [209], polycarbophil ity for sulfur components. However, pure PDMS membrane

calcium (PCP) [211], dopamine [208], hyaluronic acid [213] suffers from low selectivity and poor mechanical strength

and gelatin [212] have been ﬁrstly utilized by our group due to the high ﬂexibility of molecular chains [196,197].

in composite membrane as intermediate layer or separa- It has been conﬁrmed that the incorporation of inor-

tion layer of composite membranes for the dehydration ganic materials in polymeric matrix can enhance the

of ethanol aqueous solution. In the studies of employing mechanical properties and physicochemical stabilities of

CP and PCP as intermediate layers [209,211], the interfa- membrane. Furthermore, the hybrid membrane can cross

cial compatibility and interfacial strength were improved. the trade-off hurdle between the permeability and selec-

As a result, composite membranes with thin and intact tivity by manipulating the hydrophilicity/hydrophobicity

separation layers were fabricated. With the presence of of membrane and the arrangement of polymer chains

intermediate layer, the separation factor of composite (inﬂuencing the interchain spacing and chain rigidity)

membrane was elevated more than one order of magnitude [185,404]. PDMS–SiO2 hybrid membranes were fabricated

with desirable long-term operation stability. In particu- via in situ biomimetic mineralization method [196,197]. It

lar, the membrane utilizing PCP as the intermediate layer was revealed that employing silica precursor with higher

showed an excellent separation performance with the per- reactivity can form smaller silica nanoparticles, and the

3 −2 −1

meation ﬂux of 1.39 × 10 g m h and the separation consequent larger interfacial area engendered more hydro-

factor of 1279. gen bonds between the silanol groups on the silica surface

Membranes fabricated by self-assembly of diblock or and the oxygen atoms on the polymer chains, thus enhanc-

triblock copolymers have aroused great interest in perva- ing the mechanical strength of the membranes more

poration due to their capacity of offering continuous phase signiﬁcantly. Moreover, incorporation of silica into PDMS

for the permeate transport. PDMS [242] and polybutadiene matrix is beneﬁcial for increasing the size and number of

(PB) [242–244] are commonly utilized transporting blocks free volume cavities, which affords lower diffusion resis-

for ethanol-selective membranes. Balsara et al. [242,243] tance for the penetrant molecules. The as-prepared hybrid

and Buonomenna et al. [244] investigated the inﬂuence membrane exhibited an outstanding desulfurization per-

3 −2 −1

of molecular weight, solvent and mass ratio of different formance with a permeation ﬂux of 10.8 × 10 g m h

blocks on the morphology and ethanol/water separa- and a selectivity of 4.8 toward thiophene in model gaso-

tion performance of block copolymer membranes. The line.

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1709

Inspired by the high cohesive/adhesive energy features incorporated into polymeric matrix as the ﬁller to

of bioadhesives, dopamine nanoaggregates were prepared fabricate ultrathin and defect-free hybrid membranes

and incorporated into PDMS matrix [231]. As a result, [232]. The interfacial interaction between polymer matrix

the cohesive energy and chain rigidity of PDMS were and ﬁller was optimized by varying the molar ratio of

enhanced, which led to improved swelling resistance and Fe to DA, endowing the membrane with favorable free

thermal stability. The free volume properties of PDMS volume, which was conducive to the selective diffusion of

membrane were also optimized due to the appropriate CO2 molecules in membrane. As a result, the signiﬁcantly

intervening of dopamine nanoaggregates on the packing enhanced CO2/CH4 selectivity from 21 to 72, and the

of PDMS polymer chains. The simultaneous enhancement comprehensive performance surpassing the most recent

of permeation ﬂux and enrichment factor was achieved upper bound line were obtained. Furthermore, the mem-

3 −2 −1

with permeation ﬂux increasing from 2.78 × 10 g m h brane achieved a successful suppression of CO2-induced

3 −2 −1

to 6.90 × 10 g m h and enrichment factor increas- plasticization at high operating pressure

ing from 4.3 to 4.5, exceeding the upper-bound curve The self-assembly of block copolymer into membrane

of the PDMS control membrane. Jiang et al. [54] fabri- with highly ordered and continuous structure is attrac-

cated an ultrathin PDA coating on PSf substrate. Compared tive for mass transport through membrane and has been

with PDMS membrane, the PDA membrane exhibited investigated for the applications in CO2 separation. Cohen

higher hydrophilicity, lower thickness, higher cohesive et al. [408] studied the permeation of gases through PS-

energy, and higher adhesive strength with PSf substrate, b-PB block copolymer membranes with highly oriented

which endowed the PDA/PSf composite membrane with lamellar microstructure. The results demonstrated that

favorable pervaporation performance and long-term dura- the highest permeability was obtained when the lamel-

bility. Moreover, double or more coatings of PDA was lae were oriented parallel to the permeation direction.

necessary for pervaporation desulfurization because the The similar dependence of permeability on the direction

single-coated PDA displayed quite low selectivity toward of lamellae orientation was also discovered by Koﬁnas

thiophene. et al. [409]. Most recently, Gao et al. [407,409] synthe-

Besides PDMS, PEG is also an appropriate membrane sized block copolymers with PS segments and linear PEO or

material for pervaporation desulfurization of gasoline brush-type PEO (poly[oligo(ethylene glycol) methyl ether

according to the solubility parameter theory. Kong et al. methacrylate], POEGMA) segments. After self-assembly,

[403,405] prepared PEG-b-PAN membranes comprising of cylindrical structures were formed for both BCPs with

dispersed PEG microdomains and bulk PAN phases. An PEO cylinders oriented perpendicular to the surface. The

increase in total ﬂux and a decrease in sulfur enrichment perpendicular channel and the ether oxygen linkages

factor were obtained by decreasing PEG molecular weight in PEO segments were favor of CO2 permeation. Par-

or increasing the PEG weight content, which resulted in ticularly, the brush-type PEO segments possessed lower

higher proportion of PEG microdomains. Further research crystallinity compared with linear PEO segments, which

should be performed to elevate the pervaporation desul- endowed the cylindrical channels with high CO2 afﬁnity

furization permeability of PEG-based block copolymer and free volume, thus facilitated both the solution and

membrane. diffusion properties of CO2 molecules. As a result, the

membrane exhibited an extremely high CO2 permeance of

−7 3 −2 −1 −1

4.3. Carbon capture 5.92 × 10 m m s Pa and a comprehensive separa-

tion performance surpassing the Robeson’s upper bound

It is widely accepted that the increasing greenhouse line.

gases emissions in atmosphere, particularly CO2, caused As an enzyme existed in many organisms, carbonic

global warming in the past decades. Furthermore, the CO2 anhydrase (CA) play key roles in the transport of CO2

emissions are anticipated to increase dramatically for the in vivo. It is the fastest catalyst for CO2 hydration

foreseeable future [406,407]. International Panel on Cli- and dehydration process with a turnover number of

6 −1 −1

mate Change predicts that, by the year 2100, the level of 10 mol CO2 mol CA s , and appropriate to be utilized at

CO2 in atmosphere may rise to 570 ppmv, which is 1.5 low CO2 concentration [410]. Inspired by its high catal-

times the value of that in 2004 [407]. The technologies ysis efﬁciency, CA-immobilized membranes have been

for capturing CO2 from gaseous mixtures can be divided exploited for CO2 separation [411,412]. Zhang et al. [411]

into three categories – liquid absorption, solid adsorp- developed a hollow ﬁber membrane reactor by embed-

tion, and membrane separation [407]. Compared with ding CA in hydrogel, which exhibited a high performance

other two technologies, membrane technology offers a with CO2/N2 selectivity of 820, CO2/O2 selectivity of 330,

−10 3 −2 −1 −1

number of inherent advantages: simple operation, envi- and CO2 permeance of 3.70 × 10 m m s Pa . In

ronmentally benign process without hazardous chemicals, order to avoid the inactivation of CA in industrial-scale

small equipment, and lower energy consumption. Con- production, Wang et al. [413] prepared biomimetic poly(N-

siderable researches have been dedicated to fabricate vinylimidazole)–zinc (PVI–Zn(II)) complex to simulate the

high-performance robust membranes via biomimetic and active site of CA (a Zn(II) tetrahedral center bound to three

bioinspired strategies for the development of membrane- imidazole residues and a hydroxyl ligand) and acquire

based carbon capture technology. high-performance membrane for the separation of CO2/N2.

Intrigued by the adhesive capacity and iron-fortiﬁed The critical effect of PVI–Zn(II) complex on facilitating CO2

property of marine adhesive proteins, Fe –dopamine hydration reversibly was veriﬁed by varying the molar

organometallic nanoaggregates (Fe –DA) were ratio of PVI/Zn(II), the pH value of the PVI–Zn(II) solution,

1710 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

and replacing PVI by polyvinylpyrrolidone (PVP), which Phosphorylcholine is a biological zwitterion located at

considerably altered the amount and the structure of the the outside surface of cell membrane, which makes vital

complex. The CO2 permeance and CO2/N2 selectivity of contributions to the anti-fouling property of cell mem-

PVI–Zn(II) complex membrane were nearly three and two brane and possesses favorable biocompatibility due to

times higher than those of pure PVI membrane, respec- its zwitterionic nature and the electrostatically induced

tively. hydration [415]. Surface modiﬁcations with phospho-

rylcholine and other zwitterions have been extensively

4.4. Health care studied to improve the biocompatibility of membrane sur-

faces in recent years [95,97,98,100,110,111,118,145,147].

In recent years, health care has become an important Chang et al. [95,97,100] investigated the hemocompatibi-

application ﬁeld of membrane technology, which mainly lity of zwitterionic surfaces via grafting poly(sulfobetaine

includes diagnosis, treatment, and prevention of disease, methacrylate) (PSBMA) on membranes. The optimized

injury, and other physical and mental impairments in antifouling (low protein adsorption), anticoagulant (long

humans. Speciﬁcally, the applications of biomimetic and plasma-clotting time), and antithrombogenic (low hemol-

bioinspired membranes in health care center on artiﬁcial ysis of red blood cells solution) properties were rendered

organs including artiﬁcial kidney, lung, liver, etc. Besides when the membrane surface possessed the highest hydra-

good selective permeation and anti-fouling performance, tion capacity and the lowest charge bias. Moreover, the

the distinct requirement for membranes used in artiﬁ- PSBMA-grafted membranes exhibited excellent nonbioad-

cial organs is the compatibilities of membrane surfaces hesive characteristics in contact with tissue cells, bacterial

with surroundings, such as cytocompatibility and hemo- medium, and provided an appropriate microenvironment

compatibility [414,415]. To date, various biomimetic and for skin wound healing, which imparted the great potential

bioinspired approaches have been utilized to construct in the rational design and facile preparation of advanced

highly compatible surface by immobilizing natural or syn- wound dressings [100].

thesized macromolecules on membrane surface. Among the above approaches, the surface zwitteri-

PVP is a hydrophilic polymer with favorable biocom- onization seems to be a more attractive strategy for

patibility, which has ever been employed as blood plasma constructing biocompatible surfaces due to the excellent

substitute. Zhao et al. [414] modiﬁed PES membrane sur- performance, high diversity and easy processability.

faces with PVP through surface segregation of amphiphilic

triblock copolymer PVP-b-PMMA-b-PVP. Compared with 5. Conclusion and outlook

the PES membrane, the modiﬁed membranes exhibited

much better hemocompatibility (BSA adsorption decreased As an emerging area, biomimetics and bioinspiration

2 2

from 19 ␮g/cm to 10 ␮g/cm , platelet adhesion decreased have already won a foothold in the scientiﬁc and technical

7 2

from 25 × 10 cells/cm to nearly zero, blood coagulation arena. “Learn from nature” and “innovation through imi-

time increased from about 55 s to 90 s) and cytocompati- tation” have gradually evolved as the intriguing shortcut

bility (more ﬂat cell morphology, higher surface coverage, and pragmatic philosophy in research and development

and favorable cell viability), which endow the membranes of membranes and membrane processes. By imitating

with promising potential in the ﬁeld of blood puriﬁcation, the exceptional compositions, structures, formations and

such as hemodialysis and artiﬁcial liver. functions of biological or natural materials, a myriad

Heparin is a widely used blood anticoagulant with of biomimetic membranes and bioinspired membranes

remarkable cytocompatibility, hemocompatibility and cell have been designed and prepared using cell membrane,

proliferation capacity [230,416]. In order to graft heparin lotus, mussel as representative prototypes and biominer-

[230,416,417] and heparin analogs [416] on membrane alization, bioadhesion, self-assembly as major tools. The

surfaces, biomimetic adhesion strategy was utilized as typical progress includes: (1) By mimicking the composi-

a facile, green and effective method through coating tion, structure and formation principles of cell membrane,

dopamine-anchored heparins or precoating PDA followed different kinds of porous membranes with high perme-

by grafting heparin on the surfaces. Compared with PVP ation ﬂux and selectivity have been prepared through the

modiﬁed membranes, the dopamine-heparin modiﬁed self-assembly of block copolymer or the incorporation of

membranes exhibited more pronounced enhancement in biological/artiﬁcial nanochannels within the membrane

anticoagulation performance, with clotting time increased matrix. (2) By mimicking the composition, structure and

from 10 min to more than 60 min for PE/dopamine- formation principles of the shell of marine mussel, diverse

heparin membrane [230]. Moreover, the increased water kinds of organic–inorganic hybrid membranes have been

−2 −1 −2 −1

ﬂux (from 371.4 L m h to 644.9 L m h ) [230], visi- prepared through in situ generation of inorganic nanopar-

bly suppressed adhesion, activation and transmutation of ticles within polymer membrane matrix via biomimetic

platelets, and promoted cell attachment and growth on mineralization, and diverse kinds of composite membranes

membrane surface [230,416] were obtained due to the with robust interface between active layer and support

increased surface hydrophilicity and biological activities layer have been prepared through coating support layer

of heparin molecules. In comparison with the complex with polydopamine, etc. via biomimetic adhesion. (3) By

process and high cost of extracting heparin from animal mimicking the composition, structure and function of lotus,

body, the synthesized heparin analogs possessing similar diverse kinds of membranes with superior self-cleaning

structure and functions to heparin are more attractive for property have been prepared through electrospinning for

practical applications. hierarchically textured surfaces and surface segregation

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1711

for heterogeneous surfaces. The biomimetic and bioin- should penetrate into every corner of membrane technol-

spired membranes, which inherit high transport efﬁciency ogy from evolution to revolution.

and selectivity from biological systems, have displayed In summary, the future efforts on research and devel-

outstanding performances in almost all the energy and opment of biomimetic and bioinspired membranes will

environmental-related application spectra, whereas only be devoted to what we can understand, what we can

water treatment, clean energy production and carbon cap- recreate, what we can imitate, and what we can prepare.

ture are particularly emphasized herein. Doubtlessly, the scope of biomimetic and bioinspired

Biomimetics and bioinspiration have provided potent membranes is highly interdisciplinary, it should break

tools for the design of innovative membranes and mem- the barriers among diverse scientiﬁc disciplines, in other

brane processes. Biomimetic membranes are often limited words, the cooperative contributions from biologists,

to copying or imitating natural solutions in particular physicists, chemists, material scientists and chemical

the structure and function of cell membranes. Bioinspired engineers are deﬁnitely needed. Biomimetics and bioin-

membranes, on the other hand, expand upon biomimetic spiration, as the complementary and interchangeable

membranes, not only copying the concepts of cell mem- strategies, will play more and more crucial roles in sustain-

branes but also borrowing the preparation principles of able innovation and development of advanced membrane

natural materials for the engineering and technological technology.

implementation. Obviously, the scope of bioinspired mem-

branes is much broader and application-oriented. From this

Acknowledgements

perspective, the research and development of biomimetic

and bioinspired membranes may undergo the follow-

This work was supported by National Science Fund for

ing three transitions (1) from biomimicry, which entails

Distinguished Young Scholars (21125627), the National

merely superﬁcial imitation of the biological systems,

High Technology Research and Development Program of

(2) to biomimesis, which aims to copy and reconstruct

China (2012AA03A611), and the Program of Introducing

the structure–function relationships observed in biological

Talents of Discipline to Universities (No. B06006).

systems, and ﬁnally (3) to bioinspiration, through which

properties and performances are elevated to higher lev-

els, even surpass biological systems. In comparison to References

biomimetic membranes, bioinspired membranes are less

[1] Lipnizki F, Field RW, Ten PK. Pervaporation-based hybrid process:

mature albeit they may become more important in the

a review of process design, applications and economics. J Membr

future membrane technology. Moving from biomimetics

Sci 1999;153:183–210.

to bioinspiration will represent the translational nature of [2] Mulder M. Basic principals of membrane technology. 2nd ed. Dor-

membrane technology development. drecht, The Netherlands: Kluwer Academic Press; 1996, 564 pp.

[3] Gin DL, Noble RD. Designing the next generation of chemical sepa-

Apparently, a biomimetic and bioinspired approach

ration membranes. Science 2011;332:674–6.

to membranes and membrane processes is one of the

[4] Salta M, Wharton JA, Stoodley P, Dennington SP, Goodes LR, Wer-

most promising scientiﬁc and technological challenges winski S, Mart U, Wood RJK, Stokes KR. Designing biomimetic

antifouling surfaces. Philos Trans R Soc A 2010;368:4729–54.

in the coming decades. There are tremendous efforts

[5] Vullev VI. From biomimesis to bioinspiration: what’s the ben-

needed to input for fully exploiting the potentials of

eﬁt for solar energy conversion applications. J Phys Chem Lett

biomimetic and bioinspired membranes. First of all, new 2011;2:503–8.

[6] Kowalczyk SW, Blosser TR, Dekker C. Biomimetic nanopores: learn-

prototypes need to be excavated to establish the much

ing from and about nature. Trends Biotechnol 2011;29:607–14.

larger volume of prototype library for membrane scien-

[7] Tokarev I, Minko S. Multiresponsive, hierarchically structured

tists to choose and imitate. Second, the understanding of membranes: new, challenging, biomimetic materials for biosen-

sors, controlled release, biochemical gates, and nanoreactors. Adv

working principles and control strategies in biological sys-

Mater 2009;21:241–7.

tems should go more deeply into molecular, organelle,

[8] Abetz V, Brinkmann T, Dijkstra M, Ebert K, Fritsch D, Ohlrogge

cellular, tissue, organ, and organism levels, in particular, K, Paul D, Peinemann KV, Pereira-Nunes S, Scharnagl N, Schos-

sig M. Developments in membrane research: from material via

the structure–function relationships should be explored

process design to industrial application. Adv Eng Mater 2006;8:

more intensively. Strengthening biomimetic foundation is

328–58.

always beneﬁcial for bioinspired technology development. [9] Edidin M. Lipids on the frontier: a century of cell-membrane bilay-

Third, higher level imitation should be achieved to cre- ers. Nat Rev Mol Cell Biol 2003;4:414–8.

[10] Singer SJ, Nicolson GL. The ﬂuid mosaic model of the structure of

ate uniform or narrowly distributed membrane pores or

cell membranes. Science 1972;175:720–31.

free volume cavities, hierarchical membrane surfaces as

[11] Claassen DE, Spooner BS. Liposome formation in microgravity. Adv

well as bulk chemical and topological structures in order Space Res 1996;17:151–60.

[12] Vermette P, Meagher L. Interactions of phospholipid- and

to solve the tradeoff relation between membrane perme-

poly(ethylene glycol)-modiﬁed surfaces with biological systems:

ability and selectivity or eliminate the membrane fouling,

relation to physico-chemical properties and mechanisms. Colloids

hence, signiﬁcantly improving the membrane separation Surf B 2003;28:153–98.

[13] Andrew LL. Phosphorylcholine-based polymers and their use in the

performance. Fourth, the cost for large scale prepara-

prevention of biofouling. Colloids Surf B 2000;18:261–75.

tion of biomimetic and bioinspired membranes should

[14] Chrispeels MJ, Crawford NM, Schroeder JI. Proteins for transport of

be decreased signiﬁcantly for the practical applications, water and mineral nutrients across the membranes of plant cells.

Plant Cell 1999;11:661–75.

considering that biological materials are composed of only

[15] Zardoya R. Phylogeny and evolution of the major intrinsic protein

a few elements and the principal elements are hydrogen,

family. Biol Cell 2005;97:397–414.

carbon, nitrogen, oxygen, silicon, phosphorous, sulfur, and [16] Agre P, Bonhivers M, Borgnia MJ. The aquaporins, blueprints for

cellular plumbing systems. J Biol Chem 1998;273:14659–62.

calcium. Finally, the idea of biomimetics and bioinspiration

1712 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

[17] Sui H, Han BG, Lee JK, Walian P, Jap BK. Structural basis of [47] Stewart RJ, Wang CS, Shao H. Complex coacervates as a founda-

water-speciﬁc transport through the AQP1 water channel. Nature tion for synthetic underwater adhesives. Adv Colloid Interface Sci

2001;414:872–8. 2011;167:85–93.

[18] Preston GM, Carroll TP, Guggino WB, Agre P. Appearance of water [48] Lee H, Scherer NF, Messersmith PB. Single-molecule mechanics of

channels in xenopus oocytes expressing red cell CHIP28 protein. mussel adhesion. Proc Natl Acad Sci USA 2006;103:12999–3003.

Science 1992;256:385–7. [49] Lin Q, Gourdon D, Sun C, Holten-Andersen N, Anderson TH, Waite

[19] Meinild AK, Klaerke DA, Zeuthen T. Bidirectional water ﬂuxes and JH, Israelachvili JN. Adhesion mechanisms of the mussel foot pro-

speciﬁcity for small hydrophilic molecules in aquaporins 0–5. J Biol teins mfp-1 and mfp-3. Proc Natl Acad Sci USA 2007;104:3782–6.

Chem 1998;273:32446–51. [50] Wang CS, Stewart RJ. Multipart copolyelectrolyte adhesive of the

[20] Kozono D, Yasui M, King LS, Agre P. Aquaporin water channels: sandcastle worm, Phragmatopoma californica (Fewkes): catechol

atomic structure and molecular dynamics meet clinical medicine. oxidase catalyzed curing through peptidyl-DOPA. Biomacro-

J Clin Invest 2002;109:1395–9. molecules 2013;14:1607–17.

[21] Coleman AW, Silva ED, Nouar F, Nierlich M, Navaza A. The struc- [51] Waite JH. Nature’s underwater adhesive specialist. Int J Adhes

ture of a self-assembled calixarene aqua-channel system. Chem Adhes 1987;7:9–14.

Commun 2003;7:826–7. [52] Waite JH. Surface chemistry: mussel power. Nat Mater 2008;7:8–9.

[22] Murata K, Mitsuoka K, Hirai T, Walz T, Agre P, Heymann JB, Engel A, [53] Hong S, Na YS, Choi S, Song IT, Kim WY, Lee H. Non-covalent

Fujiyoshi Y. Structural determinants of water permeation through self-assembly and covalent polymerization co-contribute to poly-

aquaporin-1. Nature 2000;407:599–605. dopamine formation. Adv Funct Mater 2012;22:4711–7.

[23] Dutzler R, Campbell EB, MacKinnon R. Gating the selectivity ﬁlter [54] Li B, Liu WP, Jiang ZY, Dong X, Wang BY, Zhong YR. Ultrathin

in ClC chloride channels. Science 2003;300:108–12. and stable active layer of dense composite membrane enabled by

[24] Yellen G. The voltage-gated potassium channels and their relatives. poly(dopamine). Langmuir 2009;25:7368–74.

Nature 2002;419:35–42. [55] Whitesides G, Mathias J, Seto C. Molecular self-assembly and

[25] Jiang Y, Lee A, Chen J, Cadene M, Chait BT, MacKinnon R. The open nanochemistry: a chemical strategy for the synthesis of nanostruc-

pore conformation of potassium channels. Nature 2002;417:523–6. tures. Science 1991;254:1312–9.

[26] Doyle DA, Cabral JM, Pfuetzner RA, Kuo A, Gulbis JM, Cohen SL, Chait [56] Zhang S. Emerging biological materials through molecular self-

BT, MacKinnon R. The structure of the potassium channel: molecu- assembly. Biotechnol Adv 2002;20:321–39.

lar basis of K conduction and selectivity. Science 1998;280:69–77. [57] Seidel SR, Stang PJ. High-symmetry coordination cages via self-

[27] Fyles TM. Synthetic ion channels in bilayer membranes. Chem Soc assembly. Acc Chem Res 2002;35:972–83.

Rev 2007;36:335–47. [58] Hanczyc MM, Szostak JW. Replicating vesicles as models of primi-

[28] Gouaux E, MacKinnon R. Principles of selective ion transport in tive cell growth and division. Curr Opin Chem Biol 2004;8:660–4.

channels and pumps. Science 2005;310:1461–5. [59] Mouritsen OG. Self-assembly and organization of lipid–protein

[29] Sommerdijk N, Colfen H. Lessons from nature-biomimetic membranes. Curr Opin Colloid Interface Sci 1998;3:78–87.

approaches to minerals with complex structures. MRS Bull [60] Stone DA, Korley LTJ. Bioinspired polymeric nanocomposites.

2010;35:116–21. Macromolecules 2010;43:9217–26.

[30] Nudelman F, Sommerdijk NA. Biomineralization as an inspi- [61] Hagn F, Eisoldt L, Hardy JG, Vendrely C, Coles M, Scheibel T, Kessler

ration for materials chemistry. Angew Chem Int Ed Engl H. A conserved spider silk domain acts as a molecular switch that

2012;51:6582–96. controls ﬁbre assembly. Nature 2010;465:239–42.

[31] Gower LB. Biomimetic model systems for investigating the amor- [62] Askarieh G, Hedhammar M, Nordling K, Saenz A, Casals C, Rising

phous precursor pathway and its role in biomineralization. Chem A, Johansson J, Knight SD. Self-assembly of spider silk proteins is

Rev 2008;108:4551–627. controlled by a pH-sensitive relay. Nature 2010;465:236–8.

[32] Hildebrand M. Diatoms, biomineralization processes, and [63] Rising A, Hjälm G, Engström W, Johansson J. N-terminal nonrepet-

genomics. Chem Rev 2008;108:4855–74. itive domain common to dragline, ﬂagelliform, and cylindriform

[33] Michel FM, MacDonald J, Feng J, Phillips BL, Ehm L, Tarabrella spider silk proteins. Biomacromolecules 2006;7:3120–4.

C, Parise JB, Reeder RJ. Structural characteristics of syn- [64] Heim M, Keerl D, Scheibel T. Spider silk: from soluble protein to

thetic amorphous calcium carbonate. Chem Mater 2008;20: extraordinary ﬁber. Angew Chem Int Ed Engl 2009;48:3584–96.

4720–8. [65] Du C, Falini G, Fermani S, Abbott C, Moradian-Oldak J. Supramolec-

[34] Mahamid J, Sharir A, Addadi L, Weiner S. Amorphous calcium phos- ular assembly of amelogenin nanospheres into birefringent

phate is a major component of the forming ﬁn bones of zebraﬁsh: microribbons. Science 2005;307:1450–4.

indications for an amorphous precursor phase. Proc Natl Acad Sci [66] Li C, Kaplan DL. Biomimetic composites via molecular scale self-

USA 2008;105:12748–53. assembly and biomineralization. Curr Opin Solid State Mater Sci

[35] Matsunaga T, Sakaguchi T. Molecular mechanism of magnet forma- 2003;7:265–71.

tion in bacteria. J Biosci Bioeng 2000;90:1–13. [67] Zhang S. Molecular self-assembly: another brick in the wall. Nat

[36] Mann S. Biomineralization: principles and concepts in bioinorganic Nanotechnol 2006;1:169–70.

materials chemistry. New York: Oxford University Press; 2001, 210 [68] Muzzarelli C, Muzzarelli RAA. Natural and artiﬁcial

pp. chitosan–inorganic composites. J Inorg Biochem 2002;92:89–94.

[37] Xu AW, Ma Y, Cölfen H. Biomimetic mineralization. J Mater Chem [69] Levi-Kalisman Y, Falini G, Addadi L, Weiner S. Structure of the

2007;17:415–49. nacreous organic matrix of a bivalve mollusk shell examined in the

[38] Meldrum FC, Cölfen H. Controlling mineral morphologies and hydrated state using cryo-TEM. J Struct Biol 2001;135:8–17.

structures in biological and synthetic systems. Chem Rev [70] Finnemore A, Cunha P, Shean T, Vignolini S, Guldin S, Oyen M,

2008;108:4332–432. Steiner U. Biomimetic layer-by-layer assembly of artiﬁcial nacre.

[39] Tang Z, Kotov NA, Magonov S, Ozturk B. Nanostructured artiﬁcial Nat Commun 2012;3:966.

nacre. Nat Mater 2003;2:413–8. [71] Addadi L, Joester D, Nudelman F, Weiner S. Mollusk shell forma-

[40] Roth KM, Zhou Y, Yang W, Morse DE. Bifunctional small molecules tion: a source of new concepts for understanding biomineralization

are biomimetic catalysts for silica synthesis at neutral pH. J Am processes. Chem Eur J 2006;12:980–7.

Chem Soc 2004;127:325–30. [72] Liu X, Li J, Xiang L, Sun J, Zheng G, Zhang G, Wang H, Xie L, Zhang R.

[41] Dickerson MB, Sandhage KH, Naik RR. Protein- and peptide- The role of matrix proteins in the control of nacreous layer deposi-

directed syntheses of inorganic materials. Chem Rev tion during pearl formation. Proc R Soc B 2012;279:1000–7.

2008;108:4935–78. [73] Eadie L, Ghosh TK. Biomimicry in textiles: past, present and poten-

[42] Wilker JJ. The iron-fortiﬁed adhesive system of marine mussels. tial. An overview. J R Soc Interface 2011;8:761–75.

Angew Chem Int Ed Engl 2010;49:8076–8. [74] Pechook S, Pokroy B. Self-assembling, bioinspired wax crys-

[43] Silverman HG, Roberto FF. Understanding marine mussel adhesion. talline surfaces with time-dependent wettability. Adv Funct Mater

Mar Biotechnol 2007;9:661–81. 2012;22:745–50.

[44] Lee H, Dellatore SM, Miller WM, Messersmith PB. Mussel- [75] Liu K, Yao X, Jiang L. Recent developments in bio-inspired special

inspired surface chemistry for multifunctional coatings. Science wettability. Chem Soc Rev 2010;39:3240–55.

2007;318:426–30. [76] Feng L, Li S, Li Y, Li H, Zhang L, Zhai J, Song Y, Liu B, Jiang L, Zhu D.

[45] Waite JH, Andersen NH, Jewhurst S, Sun C. Mussel adhesion: ﬁnding Super-hydrophobic surfaces: from natural to artiﬁcial. Adv Mater

the tricks worth mimicking. J Adhes 2005;81:297–317. 2002;14:1857–60.

[46] Sun CJ, Srivastava A, Reifert JR, Waite JH. Halogenated DOPA in a [77] Sun T, Feng L, Gao X, Jiang L. Bioinspired surfaces with special wett-

marine adhesive protein. J Adhes 2009;85:126. ability. Acc Chem Res 2005;38:644–52.

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1713

[78] Koch K, Bhushan B, Jung YC, Barthlott W. Fabrication of artiﬁcial zwitterionic copolymer via UV-initiated polymerization. J Membr

lotus leaves and signiﬁcance of hierarchical structure for superhy- Sci 2009;342:6–13.

drophobicity and low adhesion. Soft Matter 2009;5:1386–93. [104] Ulbricht M, Yang H. Porous polypropylene membranes with

[79] Bhushan B, Jung YC, Niemietz A, Koch K. Lotus-like biomimetic hier- different carboxyl polymer brush layers for reversible protein

archical structures developed by the self-assembly of tubular plant binding via surface-initiated graft copolymerization. Chem Mater

waxes. Langmuir 2009;25:1659–66. 2005;17:2622–31.

[80] Koch K, Bhushan B, Barthlott W. Diversity of structure, morphology [105] Zhou Q, Lei XP, Li JH, Yan BF, Zhang QQ. Antifouling, adsorption and

and wetting of plant surfaces. Soft Matter 2008;4:1943–63. reversible ﬂux properties of zwitterionic grafted PVDF membrane

[81] Guo Z, Liu W. Biomimic from the superhydrophobic plant leaves prepared via physisorbed free radical polymerization. Desalination

in nature: binary structure and unitary structure. Plant Sci 2014;337:6–15.

2007;172:1103–12. [106] Li MZ, Li JH, Shao XS, Miao J, Wang JB, Zhang QQ, Xu XP.

[82] Zhu D, Li X, Zhang G, Zhang X, Zhang X, Wang T, Yang B. Mim- Grafting zwitterionic brush on the surface of PVDF membrane

icking the rice leaf-from ordered binary structures to anisotropic using physisorbed free radical grafting technique. J Membr Sci

wettability. Langmuir 2010;26:14276–83. 2012;405–406:141–8.

[83] Feng L, Zhang Y, Xi J, Zhu Y, Wang N, Xia F, Jiang L. Petal effect: [107] Li Q, Bi QY, Zhou B, Wang XL. Zwitterionic sulfobetaine-

a superhydrophobic state with high adhesive force. Langmuir grafted poly(vinylidene ﬂuoride) membrane surface with stably

2008;24:4114–9. anti-protein-fouling performance via a two-step surface polymer-

[84] Bhushan B, Jung YC. Natural and biomimetic artiﬁcial surfaces for ization. Appl Surf Sci 2012;258:4707–17.

superhydrophobicity, self-cleaning, low adhesion, and drag reduc- [108] Liu Y, Zhang S, Wang G. The preparation of antifouling ultraﬁl-

tion. Prog Mater Sci 2011;56:1–108. tration membrane by surface grafting zwitterionic polymer onto

[85] Weatherspoon MR, Cai Y, Crne M, Srinivasarao M, Sandhage KH. poly(arylene ether sulfone) containing hydroxyl groups membrane.

3D rutile titania-based structures with morpho butterﬂy wing scale Desalination 2013;316:127–36.

morphologies. Angew Chem Int Ed Engl 2008;47:7921–3. [109] Zhu Y, Zhang F, Wang D, Pei XF, Zhang W, Jin J. A novel zwit-

[86] Gu ZZ, Uetsuka H, Takahashi K, Nakajima R, Onishi H, Fujishima A, terionic polyelectrolyte grafted PVDF membrane for thoroughly

Sato O. Structural color and the lotus effect. Angew Chem Int Ed separating oil from water with ultrahigh efﬁciency. J Mater Chem

Engl 2003;42:894–7. A 2013;1:5758–65.

[87] Zheng Y, Gao X, Jiang L. Directional adhesion of superhydrophobic [110] Yuan J, Huang X, Li P, Li L, Shen J. Surface-initiated RAFT poly-

butterﬂy wings. Soft Matter 2007;3:178–82. merization of sulfobetaine from cellulose membranes to improve

[88] Liu K, Jiang L. Bio-inspired self-cleaning surfaces. Annu Rev Mater hemocompatibility and antibiofouling property. Polym Chem

Res 2012;42:231–63. 2013;4:5074–85.

[89] Hansen WR, Autumn K. Evidence for self-cleaning in gecko setae. [111] Yue WW, Li HJ, Xiang T, Qin H, Sun SD, Zhao CS. Grafting of zwitte-

Proc Natl Acad Sci USA 2005;102:385–9. rion from polysulfone membrane via surface-initiated ATRP with

[90] Autumn K, Gravish N. Gecko adhesion: evolutionary nanotechnol- enhanced antifouling property and biocompatibility. J Membr Sci

ogy. Philos Trans R Soc A 2008;366:1575–90. 2013;446:79–91.

[91] Liu M, Wang S, Wei Z, Song Y, Jiang L. Bioinspired design of a [112] Chiang YC, Chang Y, Higuchi A, Chen WY, Ruaan RC. Sulfobetaine-

superoleophobic and low adhesive water/solid interface. Adv Mater grafted poly(vinylidene ﬂuoride) ultraﬁltration membranes exhibit

2009;21:665–9. excellent antifouling property. J Membr Sci 2009;339:151–9.

[92] Bhushan B. Biomimetics: lessons from nature—an overview. Philos [113] Zhao YH, Wee KH, Bai R. Highly hydrophilic and low-protein-

Trans R Soc A 2009;367:1445–86. fouling polypropylene membrane prepared by surface modiﬁcation

[93] Reuben BG, Perl O, Morgan NL, Stratford P, Dudley LY, Hawes C. with sulfobetaine-based zwitterionic polymer through a combined

Phospholipid coatings for the prevention of membrane fouling. J surface polymerization method. J Membr Sci 2010;362:326–33.

Chem Technol Biotechnol 1995;63:85–91. [114] Liu PS, Chen Q, Liu X, Yuan B, Wu SS, Shen J, Lin SC. Grafting of

[94] Chen SF, Zheng J, Li LY, Jiang SY. Strong resistance of phosphoryl- zwitterion from cellulose membranes via ATRP for improving blood

choline self-assembled monolayers to protein adsorption: insights compatibility. Biomacromolecules 2009;10:2809–16.

into nonfouling properties of zwitterionic materials. J Am Chem Soc [115] Zhang Y, Wang Z, Lin W, Sun H, Wu L, Chen S. A facile method

2005;127:14473–8. for polyamide membrane modiﬁcation by poly(sulfobetaine

[95] Chang Y, Chang WJ, Shih YJ, Wei TC, Hsiue GH. Zwitterionic methacrylate) to improve fouling resistance. J Membr Sci

sulfobetaine-grafted poly(vinylidene ﬂuoride) membrane with 2013;446:164–70.

highly effective blood compatibility via atmospheric plasma- [116] Yi Z, Zhu LP, Zhao YF, Zhu BK, Xu YY. An extending of candi-

induced surface copolymerization. ACS Appl Mater Interfaces date for the hydrophilic modiﬁcation of polysulfone membranes

2011;3:1228–37. from the compatibility consideration: the polyethersulfone-

[96] Zhao J, Shi Q, Luan S, Song L, Yang H, Shi H, Jin J, Li X, Yin J, Stagnaro P. based amphiphilic copolymer as an example. J Membr Sci

Improved biocompatibility and antifouling property of polypropyl- 2012;390–391:48–57.

ene non-woven fabric membrane by surface grafting zwitterionic [117] Wang M, Yuan J, Huang X, Cai X, Li L, Shen J. Grafting of car-

polymer. J Membr Sci 2011;369:5–12. boxybetaine brush onto cellulose membranes via surface-initiated

[97] Chen SH, Chang Y, Lee KR, Wei TC, Higuchi A, Ho FM, Tsou CC, Ho HT, ARGET-ATRP for improving blood compatibility. Colloids Surf B

Lai JY. Hemocompatible control of sulfobetaine-grafted polypropyl- 2013;103:52–8.

ene ﬁbrous membranes in human whole blood via plasma-induced [118] Liu PS, Chen Q, Wu SS, Shen J, Lin SC. Surface modiﬁcation

surface zwitterionization. Langmuir 2012;28:17733–42. of cellulose membranes with zwitterionic polymers for resis-

[98] Zhao J, Song L, Shi Q, Luan S, Yin J. Antibacterial and hemocom- tance to protein adsorption and platelet adhesion. J Membr Sci

patibility switchable polypropylene nonwoven fabric membrane 2010;350:387–94.

surface. ACS Appl Mater Interfaces 2013;5:5260–8. [119] Azari S, Zou L. Fouling resistant zwitterionic surface modiﬁcation

[99] Yang YF, Li Y, Li QL, Wan LS, Xu ZK. Surface hydrophilization of of reverse osmosis membranes using amino acid -cysteine. Desali-

microporous polypropylene membrane by grafting zwitterionic nation 2013;324:79–86.

polymer for anti-biofouling. J Membr Sci 2010;362:255–64. [120] Cai T, Wang R, Neoh KG, Kang ET. Functional poly(vinylidene ﬂu-

[100] Jhong JF, Venault A, Hou CC, Chen SH, Wei TC, Zheng oride) copolymer membranes via surface-initiated thiol–ene click

J, Huang J, Chang Y. Surface zwitterionization of expanded reactions. Polym Chem 2011;2:1849–58.

poly(tetraﬂuoroethylene) membranes via atmospheric plasma- [121] Yu HY, Kang Y, Liu Y, Mi B. Grafting polyzwitterions onto polyamide

induced polymerization for enhanced skin wound healing. ACS by click chemistry and nucleophilic substitution on nitrogen: a

Appl Mater Interfaces 2013;5:6732–42. novel approach to enhance membrane fouling resistance. J Membr

[101] Razi F, Sawada I, Ohmukai Y, Maruyama T, Matsuyama H. The Sci 2014;449:50–7.

improvement of antibiofouling efﬁciency of polyethersulfone [122] Huang J, Wang D, Lu Y, Li M, Xu W. Surface zwitterionically func-

membrane by functionalization with zwitterionic monomers. J tionalized PVA-co-PE nanoﬁber materials by click chemistry. RSC

Membr Sci 2012;401–402:292–9. Adv 2013;3:20922–9.

[102] Susanto H, Ulbricht M. Photografted thin polymer hydrogel layers [123] Ye SH, Watanabe J, Iwasaki Y, Ishihara K. Antifouling blood puriﬁ-

on PES ultraﬁltration membranes: characterization, stability, and cation membrane composed of cellulose acetate and phospholipid

inﬂuence on separation performance. Langmuir 2007;23:7818–30. polymer. Biomaterials 2003;24:4143–52.

[103] Yu H, Cao Y, Kang G, Liu J, Li M, Yuan Q. Enhancing antifoul- [124] Wang L, Su Yl, Zheng L, Chen W, Jiang Z. Highly efﬁcient antifoul-

ing property of polysulfone ultraﬁltration membrane by grafting ing ultraﬁltration membranes incorporating zwitterionic poly

1714 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

([3-(methacryloylamino)propyl]-dimethyl(3-sulfopropyl) ammo- [146] Shen X, Zhao Y, Chen L. The construction of a zwitterionic PVDF

nium hydroxide). J Membr Sci 2009;340:164–70. membrane surface to improve biofouling resistance. Biofouling

[125] Li JH, Li MZ, Miao J, Wang JB, Shao XS, Zhang QQ. Improved surface 2013;29:991–1003.

property of PVDF membrane with amphiphilic zwitterionic copoly- [147] Zhao YF, Zhu LP, Yi Z, Zhu BK, Xu YY. Improving the hydrophilic-

mer as membrane additive. Appl Surf Sci 2012;258:6398–405. ity and fouling-resistance of polysulfone ultraﬁltration membranes

[126] Hasegawa T, Iwasaki Y, Ishihara K. Preparation of blood-compatible via surface zwitterionicalization mediated by polysulfone-based

hollow ﬁbers from a polymer alloy composed of polysulfone and 2- triblock copolymer additive. J Membr Sci 2013;440:40–7.

methacryloyloxyethyl phosphorylcholine polymer. J Biomed Mater [148] Holland NB, Qiu Y, Ruegsegger M, Marchant RE. Biomimetic engi-

Res 2002;63:333–41. neering of non-adhesive glycocalyx-like surfaces using oligosac-

[127] Su Yl, Li C. Controlled adsorption of bovine serum albumin on charide surfactant polymers. Nature 1998;392:799–801.

poly(acrylonitrile)-based zwitterionic membranes. React Funct [149] Hu MX, Fang Y, Xu ZK. Glycosylated membranes: a promising

Polym 2008;68:161–8. biomimetic material. J Appl Polym Sci 2014;131, 39658/1-13.

[128] Zhao XT, Chen WJ, Su YL, Zhu W, Peng JM, Jiang ZY, Kong L, [150] Balme S, Janot JM, Berardo L, Henn F, Bonhenry D, Kraszewski

Li YF, Liu JZ. Hierarchically engineered membrane surfaces with S, Picaud F, Ramseyer C. New bioinspired membrane made of a

superior antifouling and self-cleaning properties. J Membr Sci biological ion channel conﬁned into the cylindrical nanopore of a

2013;441:93–101. solid-state polymer. Nano Lett 2011;11:712–6.

[129] Sun Q, Su YL, Ma XL, Wang YQ, Jiang ZY. Improved antifoul- [151] Zhu B, Li J, Xu D. Porous biomimetic membranes: fabrica-

ing property of zwitterionic ultraﬁltration membrane composed tion, properties and future applications. Phys Chem Chem Phys

of acrylonitrile and sulfobetaine copolymer. J Membr Sci 2011;13:10584–92.

2006;285:299–305. [152] Shen YX, Saboe PO, Sines IT, Erbakan M, Kumar M. Biomimetic

[130] Wang T, Wang YQ, Su YL, Jiang ZY. Antifouling ultraﬁltration mem- membranes: a review. J Membr Sci 2014;454:359–81.

brane composed of polyethersulfone and sulfobetaine copolymer. [153] Tang CY, Zhao Y, Wang R, Hélix-Nielsen C, Fane AG. Desalination by

J Membr Sci 2006;280:343–50. biomimetic aquaporin membranes: review of status and prospects.

[131] Wang YQ, Wang T, Su YL, Peng FB, Wu H, Jiang ZY. Protein- Desalination 2013;308:34–40.

adsorption-resistance and permeation property of polyether- [154] Becucci L, Moncelli MR, Guidelli R. Ion carriers and channels in

sulfone and soybean phosphatidylcholine blend ultraﬁltration metal-supported lipid bilayers as probes of transmembrane and

membranes. J Membr Sci 2006;270:108–14. dipole potentials. Langmuir 2003;19:3386–92.

[132] Wang T, Wang YQ, Su YL, Jiang ZY. Improved protein-adsorption- [155] Atanasov V, Knorr N, Duran RS, Ingebrandt S, Offenhäusser A,

resistant property of PES/SPC blend membrane by adjustment of Knoll W, Köper I. Membrane on a chip: a functional tethered lipid

coagulation bath composition. Colloids Surf B 2005;46:233–9. bilayer membrane on silicon oxide surfaces. Biophys J 2005;89:

[133] Ye SH, Watanabe J, Ishihara K. Cellulose acetate hollow ﬁber 1780–8.

membranes blended with phospholipid polymer and their per- [156] Battle AR, Valenzuela SM, Mechler A, Nichols RJ, Praporski S, di Maio

formance for hemopuriﬁcation. J Biomater Sci Polym Ed 2004;15: IL, Islam H, Girard-Egrot AP, Cornell BA, Prashar J, Caruso F, Martin

981–1001. LL, Martin DK. Novel engineered ion channel provides controllable

[134] Akamatsu K, Okuyama M, Mitsumori K, Yoshino A, Nakao A, Nakao ion permeability for polyelectrolyte microcapsules coated with a

SI. Effect of the composition of the copolymer of carboxybetaine lipid membrane. Adv Funct Mater 2009;19:201–8.

and n-butylmethacrylate on low-fouling property of dynamically [157] Laredo T, Dutcher JR, Lipkowski J. Electric ﬁeld driven changes of a

formed membrane. Sep Purif Technol 2013;118:463–9. gramicidin containing lipid bilayer supported on a Au(1 1 1) surface.

[135] Nishigochi S, Ishigami T, Maruyama T, Hao Y, Ohmukai Y, Iwasaki Y, Langmuir 2011;27:10072–87.

Matsuyama H. Improvement of antifouling properties of polyvinyli- [158] Li X, Wang R, Tang C, Vararattanavech A, Zhao Y, Torres J, Fane T.

dene ﬂuoride hollow ﬁber membranes by simple dip coating of Preparation of supported lipid membranes for aquaporin Z incor-

phosphorylcholine copolymer via hydrophobic interactions. Ind poration. Colloids Surf B 2012;94:333–40.

Eng Chem Res 2014;53:2491–7. [159] Wang H, Chung TS, Tong YW, Meier W, Chen Z, Hong M,

[136] Ye SH, Watanabe J, Iwasaki Y, Ishihara K. In situ modiﬁcation on Jeyaseelan K, Armugam A. Preparation and characterization of

cellulose acetate hollow ﬁber membrane modiﬁed with phospho- pore-suspending biomimetic membranes embedded with Aqua-

lipid polymer for biomedical application. J Membr Sci 2005;249: porin Z on carboxylated polyethylene glycol polymer cushion. Soft

133–41. Matter 2011;7:7274–80.

[137] An QF, Sun WD, Zhao Q, Ji YL, Gao CJ. Study on a novel nanoﬁltration [160] Duong PHH, Chung TS, Jeyaseelan K, Armugam A, Chen Z, Yang

membrane prepared by interfacial polymerization with zwitteri- J, Hong M. Planar biomimetic aquaporin-incorporated triblock

onic amine monomers. J Membr Sci 2013;431:171–9. copolymer membranes on porous alumina supports for nanoﬁltra-

[138] Chiang YC, Chang Y, Chuang CJ, Ruaan RC. A facile zwitterionization. J Membr Sci 2012;409–410:34–43.

tion in the interfacial modiﬁcation of low bio-fouling nanoﬁltration [161] Kumar M, Grzelakowski M, Zilles J, Clark M, Meier W. Highly per-

membranes. J Membr Sci 2012;389:76–82. meable polymeric membranes based on the incorporation of the

[139] Nguyen A, Azari S, Zou L. Coating zwitterionic amino acid l-DOPA to functional water channel protein Aquaporin Z. Proc Natl Acad Sci

increase fouling resistance of forward osmosis membrane. Desali- USA 2007;104:20719–24.

nation 2013;312:82–7. [162] Wang H, Chung TS, Tong YW, Jeyaseelan K, Armugam A, Chen

[140] Azari S, Zou L. Using zwitterionic amino acid l-DOPA to mod- Z, Hong M, Meier W. Highly permeable and selective pore-

ify the surface of thin ﬁlm composite polyamide reverse osmosis spanning biomimetic membrane embedded with aquaporin Z.

membranes to increase their fouling resistance. J Membr Sci Small 2012;8:1185–90.

2012;401–402:68–75. [163] Zhong PS, Chung TS, Jeyaseelan K, Armugam A. Aquaporin-

[141] Yang R, Xu J, Ozaydin-Ince G, Wong SY, Gleason KK. Surface- embedded biomimetic membranes for nanoﬁltration. J Membr Sci

tethered zwitterionic ultrathin antifouling coatings on reverse 2012;407–408:27–33.

osmosis membranes by initiated chemical vapor deposition. Chem [164] Sun G, Chung TS, Jeyaseelan K, Armugam A. A layer-by-layer self-

Mater 2011;23:1263–72. assembly approach to developing an aquaporin-embedded mixed

[142] Ji YL, Zhao Q, An QF, Shao LL, Lee KR, Xu ZK, Gao CJ. Novel separa- matrix membrane. RSC Adv 2013;3:473–81.

tion membranes based on zwitterionic colloid particles: tunable [165] Zhao Y, Qiu C, Li X, Vararattanavech A, Shen W, Torres J, Hélix-

selectivity and enhanced antifouling property. J Mater Chem A Nielsen C, Wang R, Hu X, Fane AG, Tang CY. Synthesis of

2013;1:12213–20. robust and high-performance aquaporin-based biomimetic mem-

[143] Ji YL, An QF, Zhao Q, Sun WD, Lee KR, Chen HL, Gao CJ. Novel com- branes by interfacial polymerization-membrane preparation and

posite nanoﬁltration membranes containing zwitterions with high RO performance characterization. J Membr Sci 2012;423–424:

permeate ﬂux and improved anti-fouling performance. J Membr Sci 422–8.

2012;390-391:243–53. [166] Yameen B, Ali M, Neumann R, Ensinger W, Knoll W, Azzaroni

[144] Tripathi BP, Dubey NC, Choudhury S, Simon F, Stamm M. Antifoul- O. Synthetic proton-gated ion channels via single solid-state

ing and antibiofouling pH responsive block copolymer based nanochannels modiﬁed with responsive polymer brushes. Nano

membranes by selective surface modiﬁcation. J Mater Chem B Lett 2009;9:2788–93.

2013;1:3397–409. [167] Hou X, Guo W, Jiang L. Biomimetic smart nanopores and nanochan-

[145] Yi Z, Zhu LP, Xu YY, Gong XN, Zhu BK. Surface zwitterionicalization nels. Chem Soc Rev 2011;40:2385.

of poly(vinylidene ﬂuoride) porous membranes by post-reaction of [168] Gyurcsányi RE. Chemically-modiﬁed nanopores for sensing. Trends

the amphiphilic precursor. J Membr Sci 2011;385–386:57–66. Anal Chem 2008;27:627–39.

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1715

[169] Xu T, Zhao N, Ren F, Hourani R, Lee MT, Shu JY, Mao S, Helms BA. [195] Klaysom C, Moon SH, Ladewig BP, Lu GQM, Wang LZ. The inﬂu-

Subnanometer porous thin ﬁlms by the co-assembly of nanotube ence of inorganic ﬁller particle size on composite ion-exchange

subunits and block copolymers. ACS Nano 2011;5:1376–84. membranes for desalination. J Phys Chem C 2011;115:15124–32.

[170] Barboiu M, Gilles A. From natural to bioassisted and biomimetic [196] Li B, Yu SN, Jiang ZY, Liu WP, Cao RJ, Wu H. Efﬁcient desulfuriza-

artiﬁcial water channel systems. Acc Chem Res 2013;46:2814–23. tion by polymer–inorganic nanocomposite membranes fabricated

[171] Wang X, Smirnov S. Label-free DNA sensor based on surface charge in reverse microemulsion. J Hazard Mater 2012;211–212:296–303.

modulated ionic conductance. ACS Nano 2009;3:1004–10. [197] Li B, Liu WP, Wu H, Yu SN, Cao RJ, Jiang ZY. Desulfurization of model

[172] Hinds BJ, Chopra N, Rantell T, Andrews R, Gavalas V, Bachas gasoline by bioinspired oleophilic nanocomposite membranes. J

LG. Aligned multiwalled carbon nanotube membranes. Science Membr Sci 2012;415–416:278–87.

2004;303:62–5. [198] Cheng QL, Pan FS, Chen B, Jiang ZY. Preparation and dehumidiﬁca-

[173] Hou X, Zhang H, Jiang L. Building bio-inspired artiﬁcial function performance of composite membrane with PVA/gelatin–silica

tional nanochannels: from symmetric to asymmetric modiﬁcation. hybrid skin layer. J Membr Sci 2010;363:316–25.

Angew Chem Int Ed Engl 2012;51:5296–307. [199] Zhu H, Jiang R, Xiao L, Chang Y, Guan Y, Li X, Zeng G. Photocat-

[174] Han C, Hou X, Zhang H, Guo W, Li H, Jiang L. Enantioselective recog- alytic decolorization and degradation of Congo Red on innovative

nition in biomimetic single artiﬁcial nanochannels. J Am Chem Soc crosslinked chitosan/nano-CdS composite catalyst under visible

2011;133:7644–7. light irradiation. J Hazard Mater 2009;169:933–40.

[175] Ali M, Yameen B, Cervera J, Ramírez P, Neumann R, Ensinger W, [200] Copello GJ, Varela F, Vivot RM, Diaz LE. Immobilized chitosan as

Knoll W, Azzaroni O. Layer-by-layer assembly of polyelectrolytes biosorbent for the removal of Cd(II), Cr(III) and Cr(VI) from aqueous

into ionic current rectifying solid-state nanopores: insights from solutions. Bioresour Technol 2008;99:6538–44.

theory and experiment. J Am Chem Soc 2010;132:8338–48. [201] Xiong Y, Liu QL, Zhu AM, Huang SM, Zeng QH. Performance of

[176] Hou X, Liu Y, Dong H, Yang F, Li L, Jiang L. A pH-gating ionic organic–inorganic hybrid anion-exchange membranes for alkaline

transport nanodevice: asymmetric chemical modiﬁcation of single direct methanol fuel cells. J Power Sources 2009;186:328–33.

nanochannels. Adv Mater 2010;22:2440–3. [202] Lin X, Wu C, Wu Y, Xu T. Free-standing hybrid anion-exchange

[177] Tian Y, Hou X, Jiang L. Biomimetic ionic rectiﬁer systems: asym- membranes for application in fuel cells. J Appl Polym Sci

metric modiﬁcation of single nanochannels by ion sputtering 2012;123:3644–51.

technology. J Electroanal Chem 2011;656:231–6. [203] Junginger M, Kita-Tokarczyk K, Schuster T, Reiche J, Schacher F,

[178] Fornasiero F, Park HG, Holt JK, Stadermann M, Grigoropoulos CP, Müller AHE, Cölfen H, Taubert A. Calcium phosphate mineraliza-

Noy A, Bakajin O. Ion exclusion by sub-2-nm carbon nanotube tion beneath a polycationic monolayer at the air–water interface.

pores. Proc Natl Acad Sci USA 2008;105:17250–5. Macromol Biosci 2010;10:1084–92.

[179] Geng J, Kim K, Grigoropoulos C, Ajo-Franklin C, Noy A. Biomimetic [204] Liu L, He D, Wang GS, Yu SH. Bioinspired crystallization of

membrane channels based on carbon nanotubes. Biophys J CaCO3 coatings on electrospun cellulose acetate ﬁber scaf-

2013;104:545a–6a. folds and corresponding CaCO3 microtube networks. Langmuir

[180] Berezhkovskii A, Hummer G. Single-ﬁle transport of water 2011;27:7199–206.

molecules through a carbon nanotube. Phys Rev Lett [205] Zhang YF, Wu H, Li J, Li L, Jiang YJ, Jiang Y, Jiang ZY. Protamine-

2002;89:064503. templated biomimetic hybrid capsules: efﬁcient and stable carrier

[181] Joseph S, Aluru NR. Why are carbon nanotubes fast transporters of for enzyme encapsulation. Chem Mater 2007;20:1041–8.

water? Nano Lett 2008;8:452–8. [206] Chen XN, Wan LS, Wu QY, Zhi SH, Xu ZK. Mineralized

[182] Kalra A, Garde S, Hummer G. Osmotic water transport polyacrylonitrile-based ultraﬁltration membranes with improved

through carbon nanotube membranes. Proc Natl Acad Sci water ﬂux and rejection towards dye. J Membr Sci 2013;441:112–9.

USA 2003;100:10175–80. [207] Baskar D, Balu R, Kumar TSS. Mineralization of pristine chitosan ﬁlm

[183] Majumder M, Chopra N, Hinds BJ. Effect of tip functionalization on through biomimetic process. Int J Biol Macromol 2011;49:385–9.

transport through vertically oriented carbon nanotube membranes. [208] Chen J, Chen X, Yin X, Ma J, Jiang ZY. Bioinspired fabrication of com-

J Am Chem Soc 2005;127:9062–70. posite pervaporation membranes with high permeation ﬂux and

[184] Hall AR, Scott A, Rotem D, Mehta KK, Bayley H, Dekker C. Hybrid structural stability. J Membr Sci 2009;344:136–43.

pore formation by directed insertion of alpha-haemolysin into [209] Ma J, Zhang M, Wu H, Yin X, Chen J, Jiang ZY. Mussle-inspired

solid-state nanopores. Nat Nanotechnol 2010;5:874–7. fabrication of structurally stable chitosan/polyacrylonitrile com-

[185] Peng FB, Lu LY, Sun HL, Wang YQ, Liu JQ, Jiang ZY. Hybrid posite membrane for pervaporation dehydration. J Membr Sci

organic–inorganic membrane: solving the tradeoff between per- 2010;348:150–9.

meability and selectivity. Chem Mater 2005;17:6790–6. [210] Oh KH, Choo MJ, Lee H, Park KH, Park JK, Choi JW. Mussel-inspired

[186] Pan FS, Cheng QL, Jia HP, Jiang ZY. Facile approach to polydopamine-treated composite electrolytes for long-term oper-

polymer–inorganic nanocomposite membrane through a ations of polymer electrolyte membrane fuel cells. J Mater Chem A

biomineralization-inspired process. J Membr Sci 2010;357:171–7. 2013;1:14484–90.

[187] Li YF, He GW, Wang SF, Yu SN, Pan FS, Wu H, Jiang ZY. Recent [211] Zhao CH, Wu H, Li XS, Pan FS, Li YF, Zhao J, Jiang ZY, Zhang P, Cao XZ,

advances in the fabrication of advanced composite membranes. J Wang BY. High performance composite membranes with a poly-

Mater Chem A 2013;1:10058–77. carbophil calcium transition layer for pervaporation dehydration

[188] Aroon MA, Ismail AF, Matsuura T, Montazer-Rahmati MM. Perfor- of ethanol. J Membr Sci 2013;429:409–17.

mance studies of mixed matrix membranes for gas separation: a [212] Zhao J, Ma J, Chen J, Pan FS, Jiang ZY. Experimental and

review. Sep Purif Technol 2010;75:229–42. molecular simulation investigations on interfacial characteristics

[189] Zhao J, Wang F, Pan FS, Zhang MX, Yang XY, Li P, Jiang ZY, Zhang of gelatin/polyacrylonitrile composite pervaporation membrane.

P, Cao XZ, Wang BY. Enhanced pervaporation dehydration perfor- Chem Eng J 2011;178:1–7.

mance of ultrathin hybrid membrane by incorporating bioinspired [213] Ma J, Zhang MH, Jiang ZY, Nie MC, Liu GX. Facile fabrication of

multifunctional modiﬁer and TiCl4 into chitosan. J Membr Sci structurally stable hyaluronic acid-based composite membranes

2013;446:395–404. inspired by bioadhesion. J Membr Sci 2010;364:290–7.

[190] Studart AR. Towards high-performance bioinspired composites. [214] Yu ME, Hwang JY, Deming TJ. Role of l-3,4-dihydroxyphenylalanine

Adv Mater 2012;24:5024–44. in mussel adhesive proteins. J Am Chem Soc 1999;121:5825–6.

[191] Zhang L, Shi JF, Jiang ZY, Jiang YJ, Meng RJ, Zhu YY, Liang YP, [215] Pan FS, Jia HP, Qiao SZ, Jiang ZY, Wang JT, Wang BY, Zhong YR.

Zheng Y. Facile preparation of robust microcapsules by manipulat- Bioinspired fabrication of high performance composite membranes

ing metal-coordination interaction between biomineral layer and with ultrathin defect-free skin layer. J Membr Sci 2009;341:279–85.

bioadhesive layer. ACS Appl Mater Interfaces 2011;3:597–605. [216] Han G, Zhang S, Li X, Widjojo N, Chung TS. Thin ﬁlm compos-

[192] Malinova K, Gunesch M, Montero Pancera S, Wengeler R, Rieger ite forward osmosis membranes based on polydopamine modiﬁed

B, Volkmer D. Production of CaCO3/hyperbranched polyglycidol polysulfone substrates with enhancements in both water ﬂux and

hybrid ﬁlms using spray-coating technique. J Colloid Interface Sci salt rejection. Chem Eng Sci 2012;80:219–31.

2012;374:61–9. [217] Shi GM, Chung TS. Thin ﬁlm composite membranes on ceramic

[193] Pan FS, Jia HP, Cheng QL, Jiang ZY. Bio-inspired fabrication of com- for pervaporation dehydration of isopropanol. J Membr Sci

posite membranes with ultrathin polymer–silica nanohybrid skin 2013;448:34–43.

layer. J Membr Sci 2010;362:119–26. [218] Cheng C, Li S, Zhao W, Wei Q, Nie S, Sun S, Zhao C. The hydrodynamic

[194] Kayser MJ, Reinholdt MX, Kaliaguine S. Amine grafted silica/SPEEK permeability and surface property of polyethersulfone ultraﬁltra-

nanocomposites as proton exchange membranes. J Phys Chem B tion membranes with mussel-inspired polydopamine coatings. J

2010;114:8387–95. Membr Sci 2012;417–418:228–36.

1716 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

[219] Xi ZY, Xu YY, Zhu LP, Wang Y, Zhu BK. A facile method of surface [241] Buonomenna MG, Golemme G, Tone CM, De Santo MP, Ciuchi F, Per-

modiﬁcation for hydrophobic polymer membranes based on the rotta E. Nanostructured poly(styrene-b-butadiene-b-styrene) (SBS)

adhesive behavior of poly(DOPA) and poly(dopamine). J Membr Sci membranes for the separation of nitrogen from natural has. Adv

2009;327:244–53. Funct Mater 2012;22:1759–67.

[220] Kasemset S, Lee A, Miller DJ, Freeman BD, Sharma MM. Effect of [242] Jha AK, Chen L, Offeman RD, Balsara NP. Effect of nanoscale mor-

polydopamine deposition conditions on fouling resistance, physi- phology on selective ethanol transport through block copolymer

cal properties, and permeation properties of reverse osmosis mem- membranes. J Membr Sci 2011;373:112–20.

branes in oil/water separation. J Membr Sci 2013;425–426:208–16. [243] Jha AK, Tsang SL, Ozcam AE, Offeman RD, Balsara NP. Master

[221] McCloskey BD, Park HB, Ju H, Rowe BW, Miller DJ, Chun BJ, Kin curve captures the effect of domain morphology on ethanol per-

K, Freeman BD. Inﬂuence of polydopamine deposition conditions vaporation through block copolymer membranes. J Membr Sci

on pure water ﬂux and foulant adhesion resistance of reverse 2012;401–402:125–31.

osmosis, ultraﬁltration, and microﬁltration membranes. Polymer [244] Buonomenna MG, Golemme G, Tone CM, De Santo MP, Ciuchi F,

2010;51:3472–85. Perrotta E, Zappone B, Galiano F, Figoli A. Ordering phenomena in

[222] Miller DJ, Araújo PA, Correia PB, Ramsey MM, Kruithof JC, van nanostructured poly(styrene-b-butadiene-b-styrene) (SBS) mem-

Loosdrecht MCM, Freeman BD, Paul DR, Whiteley M, Vrouwen- branes for selective ethanol transport. J Membr Sci 2011;385–386:

velder JS. Short-term adhesion and long-term biofouling testing 162–70.

of polydopamine and poly(ethylene glycol) surface modiﬁcations [245] Choi WH, Jo WH. Preparation of new proton exchange membrane

of membranes and feed spacers for biofouling control. Water Res based on self-assembly of poly(styrene-co-styrene sulfonic acid)-

2012;46:3737–53. b-poly(methyl methacrylate)/poly(vinylidene ﬂuoride) blend. J

[223] Li X, Zhu L, Jiang J, Yi Z, Zhu B, Xu Y. Hydrophilic nanoﬁltration mem- Power Sources 2009;188:127–31.

branes with self-polymerized and strongly-adhered polydopamine [246] Sun L, Guo J, Zhou J, Xu Q, Chu D, Chen R. Novel nanostructured

as separating layer. Chin J Polym Sci 2012;30:152–63. high-performance anion exchange ionomers for anion exchange

[224] Azari S, Zou L, Cornelissen E, Mukai Y. Facile fouling resistant sur- membrane fuel cells. J Power Sources 2012;202:70–7.

face modiﬁcation of microﬁltration cellulose acetate membranes [247] Elabd YA, Napadensky E, Walker CW, Winey KI. Transport proper-

by using amino acid L-DOPA. Water Sci Technol 2013;68:901–8. ties of sulfonated poly(styrene-b-isobutylene-b-styrene) triblock

[225] Wang JT, Xiao LL, Zhao YN, Wu H, Jiang ZY, Hou WQ. A facile copolymers at high ion-exchange capacities. Macromolecules

surface modiﬁcation of Naﬁon membrane by the formation of 2006;39:399–407.

self-polymerized dopamine nano-layer to enhance the methanol [248] Phillip WA, Rzayev J, Hillmyer MA, Cussler EL. Gas and water liq-

barrier property. J Power Sources 2009;192:336–43. uid transport through nanoporous block copolymer membranes. J

[226] Miller DJ, Huang X, Li H, Kasemset S, Lee A, Agnihotri D, Hayes T, Paul Membr Sci 2006;286:144–52.

DR, Freeman BD. Fouling-resistant membranes for the treatment [249] Lee JS, Hirao A, Nakahama S. Polymerization of monomers contain-

of ﬂowback water from hydraulic shale fracturing: a pilot study. J ing functional silyl groups. 5. Synthesis of new porous membranes

Membr Sci 2013;437:265–75. with functional groups. Macromolecules 1988;21:274–6.

[227] Gong YK, Liu LP, Messersmith PB. Doubly biomimetic catecholic [250] Joo W, Kim HJ, Kim JK. Broadband antireﬂection coating covering

phosphorylcholine copolymer: a platform strategy for fabricating from visible to near infrared wavelengths by using multilayered

antifouling surfaces. Macromol Biosci 2012;12:979–85. nanoporous block copolymer ﬁlms. Langmuir 2009;26:5110–4.

[228] Yang H, Lan Y, Zhu W, Li W, Xu D, Cui J, Shen D, Li G. [251] Yang SY, Park J, Yoon J, Ree M, Jang SK, Kim JK. Virus ﬁltration mem-

Polydopamine-coated nanoﬁbrous mats as a versatile platform branes prepared from nanoporous block copolymers with good

for producing porous functional membranes. J Mater Chem dimensional stability under high pressures and excellent solvent

2012;22:16994–7001. resistance. Adv Funct Mater 2008;18:1371–7.

[229] Zhu LP, Jiang JH, Zhu BK, Xu YY. Immobilization of bovine serum [252] Bang J, Kim SH, Drockenmuller E, Misner MJ, Russell TP, Hawker CJ.

albumin onto porous polyethylene membranes using strongly Defect-free nanoporous thin ﬁlms from ABC triblock copolymers. J

attached polydopamine as a spacer. Colloids Surf B 2011;86:111–8. Am Chem Soc 2006;128:7622–9.

[230] Jiang JH, Zhu LP, Li XL, Xu YY, Zhu BK. Surface modiﬁcation of [253] Tang C, Bang J, Stein GE, Fredrickson GH, Hawker CJ, Kramer EJ,

PE porous membranes based on the strong adhesion of poly- Sprung M, Wang J. Square packing and structural arrangement

dopamine and covalent immobilization of heparin. J Membr Sci of ABC triblock copolymer spheres in thin ﬁlms. Macromolecules

2010;364:194–202. 2008;41:4328–39.

[231] Liu WP, Li YF, Meng XX, Liu GH, Hu S, Pan FS, Wu H, Jiang ZY, [254] Kim E, Shin C, Ahn H, Ryu DY, Bang J, Hawker CJ, Russell TP. Size con-

Wang BY, Li ZX, Cao XZ. Embedding dopamine nanoaggregates into trol and registration of nano-structured thin ﬁlms by cross-linkable

a poly(dimethylsiloxane) membrane to confer controlled inter- units. Soft Matter 2008;4:475–9.

actions and free volume for enhanced separation performance. J [255] Joo W, Park MS, Kim JK. Block copolymer ﬁlm with sponge-

Mater Chem A 2013;1:3713–23. like nanoporous structure for antireﬂection coating. Langmuir

[232] Li YF, Wang SF, Wu H, Wang JT, Jiang ZY. Bioadhesion-inspired 2006;22:7960–3.

polymer–inorganic nanohybrid membranes with enhanced CO2 [256] Xu T, Stevens J, Villa JA, Goldbach JT, Guarini KW, Black CT,

capture properties. J Mater Chem 2012;22:19617–20. Hawker CJ, Russell TP. Block copolymer surface reconstruction: a

[233] Wu J, Zhang L, Wang Y, Long Y, Gao H, Zhang X, Zhao N, Cai Y, reversible route to nanoporous ﬁlms. Adv Funct Mater 2003;13:

Xu J. Mussel-inspired chemistry for robust and surface-modiﬁable 698–702.

multilayer ﬁlms. Langmuir 2011;27:13684–91. [257] Park SC, Jung H, Fukukawa K, Campos LM, Lee K, Shin K, Hawker

[234] Kim JK, Yang SY, Lee Y, Kim Y. Functional nanomaterials based on CJ, Ha JS, Bang J. Highly ordered nanoporous thin ﬁlms by blending

block copolymer self-assembly. Prog Polym Sci 2010;35:1325–49. of PSt-b-PMMA block copolymers and PEO additives as structure

[235] van Rijn P, Tutus M, Kathrein C, Zhu L, Wessling M, Schwaneberg directing agents. J Polym Sci A: Polym Chem 2008;46:8041–8.

U, Boker A. Challenges and advances in the ﬁeld of self-assembled [258] Yang SY, Ryu I, Kim HY, Kim JK, Jang SK, Russell TP. Nanoporous

membranes. Chem Soc Rev 2013;42:6578–92. membranes with ultrahigh selectivity and ﬂux for the ﬁltration of

[236] Theato P, Ungar G. Nanoporous ordered materials: osmotically viruses. Adv Mater 2006;18:709–12.

shocked. Nat Mater 2012;11:16–7. [259] Li X, Fustin CA, Lefevre N, Gohy JF, Feyter SD, Baerdemaeker JD,

[237] Hawker CJ, Russell TP. Block copolymer lithography: merging Egger W, Vankelecom IFJ. Ordered nanoporous membranes based

“bottom-up” with “top-down” processes. MRS Bull 2005;30: on diblock copolymers with high chemical stability and tunable

952–66. separation properties. J Mater Chem 2010;20:4333–9.

[238] Li X, Tian T, Leolukman M, Wang Y, Jiang L. A supramolecular [260] Kim DH, Lau KHA, Joo W, Peng J, Jeong U, Hawker CJ, Kim JK, Russell

approach to probing the inﬂuence of micro-phase structure on TP, Knoll W. An optical waveguide study on the nanopore formation

gas permeability of block copolymer membranes. Sci Adv Mater in block copolymer/homopolymer thin ﬁlms by selective solvent

2013;5:719–26. swelling. J Phys Chem B 2006;110:15381–8.

[239] Xue B, Gao L, Jiang H, Geng Z, Guan S, Wang Y, Liu Z, Jiang L. High ﬂux [261] Jeong U, Ryu DY, Kho DH, Lee DH, Kim JK, Russell TP. Phase behavior

CO2 transporting nanochannel fabricated by the self-assembly of a of mixtures of block copolymer and homopolymers in thin ﬁlms and

linear-brush block copolymer. J Mater Chem A 2013;1:8097–100. bulk. Macromolecules 2003;36:3626–34.

[240] Querelle SE, Chen L, Hillmyer MA, Cussler EL, Nijmeijer K, [262] Jeong U, Ryu DY, Kho DH, Kim JK, Goldbach JT, Kim DH, Rus-

Wessling M. Block copolymer derived membranes for sus- sell TP. Enhancement in the orientation of the microdomain in

tained carbon dioxide–methane separations. Ind Eng Chem Res block copolymer thin ﬁlms upon the addition of homopolymer. Adv

2010;49:12051–9. Mater 2004;16:533–6.

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1717

[263] Jeong U, Ryu DY, Kim JK, Kim DH, Wu X, Russell TP. Precise control [286] Kuila BK, Stamm M. Supramolecular complex of poly(styrene)-

of nanopore size in thin ﬁlm using mixtures of asymmetric block b-poly(4-vinylpyridine) and 1-pyrenebutyric acid in thin ﬁlm.

copolymer and homopolymer. Macromolecules 2003;36:10126–9. Macromol Symp 2011;303:85–94.

[264] Phillip WA, O’Neill B, Rodwogin M, Hillmyer MA, Cussler EL. [287] Zhang P, Gao J, Li B, Han Y. Surface morphology evolution of a thin

Self-assembled block copolymer thin films as water filtration mem- polymeric supramolecular film by tuning interactions. Macromol

branes. ACS Appl Mater Interfaces 2010;2:847–53. Rapid Commun 2006;27:295–301.

[265] Phillip WA, Hillmyer MA, Cussler EL. Cylinder orientation mech- [288] Gao J, Zhang P, Fu J, Li B, Han Y, Yu X, Pan C. Surface

anism in block copolymer thin ﬁlms upon solvent evaporation. morphology evolution of poly(styrene-block-4-vinylpyridine) (PS-

Macromolecules 2010;43:7763–70. b-P4VP)(H+) and poly(methyl methacrylate)-dibenzo-18-crown-

[266] Guo S, Rzayev J, Bailey TS, Zalusky AS, Olayo-Valles R, Hillmyer 6-poly(methyl methacrylate) (PMCMA) supramolecular ﬁlm.

MA. Nanopore and nanobushing arrays from ABC triblock thin Polymer 2007;48:2425–33.

ﬁlms containing two etchable blocks. Chem Mater 2006;18: [289] Laforgue A, Bazuin CG, Prud’homme RE. A study of the supramolec-

1719–21. ular approach in controlling diblock copolymer nanopattern-

[267] Querelle SE, Jackson EA, Cussler EL, Hillmyer MA. Ultraﬁltration ing and nanoporosity on surfaces. Macromolecules 2006;39:

membranes with a thin poly(styrene)-b-poly(isoprene) selective 6473–82.

layer. ACS Appl Mater Interfaces 2013;5:5044–50. [290] Kosonen H, Valkama S, Nykänen A, Toivanen M, ten Brinke G,

[268] Chen L, Phillip WA, Cussler EL, Hillmyer MA. Robust nanoporous Ruokolainen J, Ikkala O. Functional porous structures based on the

membranes templated by a doubly reactive block copolymer. J Am pyrolysis of cured templates of block copolymer and phenolic resin.

Chem Soc 2007;129:13786–7. Adv Mater 2006;18:201–5.

[269] Amendt MA, Chen L, Hillmyer MA. Formation of nanostructured [291] Fustin CA, Guillet P, Misner MJ, Russell TP, Schubert US, Gohy JF.

poly(dicyclopentadiene) thermosets using reactive block poly- Self-assembly of metallo-supramolecular block copolymers in thin

mers. Macromolecules 2010;43:3924–34. ﬁlms. J Polym Sci A: Polym Chem 2008;46:4719–24.

[270] Mao H, Arrechea PL, Bailey TS, Johnson BJS, Hillmyer MA. Con- [292] Fustin CA, Lohmeijer BGG, Duwez AS, Jonas AM, Schubert US,

trol of pore hydrophilicity in ordered nanoporous polystyrene Gohy JF. Nanoporous thin ﬁlms from self-assembled metallo-

using an AB/AC block copolymer blending strategy. Faraday Discuss supramolecular block copolymers. Adv Mater 2005;17:1162–5.

2005;128:149–62. [293] Mugemana C, Gohy JF, Fustin CA. Functionalized nanoporous thin

[271] Mao H, Hillmyer MA. Macroscopic samples of polystyrene ﬁlms from metallo-supramolecular diblock copolymers. Langmuir

with ordered three-dimensional nanochannels. Soft Matter 2012;28:3018–23.

2006;2:57–9. [294] Guillet P, Fustin CA, Wouters D, Hoeppener S, Schubert US, Gohy JF.

[272] Kato T, Hillmyer MA. Functionalized nanoporous polyethylene Amphiphilic brushes from metallo-supramolecular block copoly-

derived from miscible block polymer blends. ACS Appl Mater Inter- mers. Soft Matter 2009;5:1460–5.

faces 2013;5:291–300. [295] Peinemann KV, Abetz V, Simon PFW. Asymmetric superstructure

[273] Kang M, Moon B. Synthesis of photocleavable poly(styrene-block- formed in a block copolymer via phase separation. Nat Mater

ethylene oxide) and its self-assembly into nanoporous thin ﬁlms. 2007;6:992–6.

Macromolecules 2008;42:455–8. [296] Nunes SP, Behzad AR, Hooghan B, Sougrat R, Karunakaran M,

[274] Schumers JM, Vlad A, Huynen I, Gohy JF, Fustin CA. Functional- Pradeep N, Vainio U, Peinemann KV. Switchable pH-responsive

ized nanoporous thin ﬁlms from photocleavable block copolymers. polymeric membranes prepared via block copolymer micelle

Macromol Rapid Commun 2012;33:199–205. assembly. ACS Nano 2011;5:3516–22.

[275] Ryu JH, Park S, Kim B, Klaikherd A, Russell TP, Thayumanavan S. [297] Nunes SP, Sougrat R, Hooghan B, Anjum DH, Behzad AR, Zhao L,

Highly ordered gold nanotubes using thiols at a cleavable block Pradeep N, Pinnau I, Vainio U, Peinemann KV. Ultraporous ﬁlms

copolymer interface. J Am Chem Soc 2009;131:9870–1. with uniform nanochannels by block copolymer micelles assembly.

[276] Zhang M, Yang L, Yurt S, Misner MJ, Chen JT, Coughlin EB, Macromolecules 2010;43:8079–85.

Venkataraman D, Russell TP. Highly ordered nanoporous thin ﬁlms [298] Nunes SP, Karunakaran M, Pradeep N, Behzad AR, Hooghan B,

from cleavable polystyrene-block-poly(ethylene oxide). Adv Mater Sougrat R, He H, Peinemann KV. From micelle supramolecular

2007;19:1571–6. assemblies in selective solvents to isoporous membranes. Langmuir

[277] Mäki-Ontto R, de Moel K, de Odorico W, Ruokolainen J, Stamm M, 2011;27:1018–90.

ten Brinke G, Ikkala O. Hairy tubes: mesoporous materials contain- [299] Madhavan P, Peinemann KV, Nunes SP. Complexation-tailored

ing hollow self-organized cylinders with polymer brushes at the morphology of asymmetric block copolymer membranes. ACS Appl

walls. Adv Mater 2001;13:117–21. Mater Interfaces 2013;5:7152–9.

[278] Ruokolainen J, Mäkinen R, Torkkeli M, Mäkelä T, Serimaa R, Brinke [300] Phillip WA, Mika Dorin R, Werner J, Hoek EMV, Wiesner U,

Gt, Ikkala O. Switching supramolecular polymeric materials with Elimelech M. Tuning structure and properties of graded tri-

multiple length scales. Science 1998;280:557–60. block terpolymer-based mesoporous and hybrid ﬁlms. Nano Lett

[279] du Sart GG, Vukovic I, Vukovic Z, Polushkin E, Hiekkataipale P, 2011;11:2892–900.

Ruokolainen J, Loos K, ten Brinke G. Nanoporous network channels [301] Wang Y, Li F. An emerging pore-making strategy: conﬁned

from self-assembled triblock copolymer supramolecules. Macro- swelling-induced pore generation in block copolymer materials.

mol Rapid Commun 2011;32:366–70. Adv Mater 2011;23:2134–48.

[280] Fahmi AW, Gutmann JS, Vogel R, Gindy N, Stamm M. Rheo- [302] Wang Y, He C, Xing W, Li F, Tong L, Chen Z, Liao X, Steinhart

logy pathway to macroscale ordered nanostructures of polymeric M. Nanoporous metal membranes with bicontinuous morphol-

nanotemplates: nanopores, nanosheets and nanoﬁbers. Macromol ogy from recyclable block-copolymer templates. Adv Mater

Mater Eng 2006;291:1061–73. 2010;22:2068–72.

[281] Luchnikov V, Kondyurin A, Formanek P, Lichte H, Stamm M. Moiré [303] Wang Z, Yao X, Wang Y. Swelling-induced mesoporous block

patterns in superimposed nanoporous thin ﬁlms derived from copolymer membranes with intrinsically active surfaces for size-

block-copolymer assemblies. Nano Lett 2007;7:3628–32. selective separation. J Mater Chem 2012;22:20542–8.

[282] Kondyurin A, Bilek M, Janke A, Stamm M, Luchnikov V. Nano- [304] Zavala-Rivera P, Channon K, Nguyen V, Sivaniah E, Kabra D,

structured carbonized thin ﬁlms produced by plasma immersion Friend RH, Nataraj SK, Al-Muhtaseb SA, Hexemer A, Calvo ME,

ion implantation of block-copolymer assemblies. Plasma Process Miguez H. Collective osmotic shock in ordered materials. Nat Mater

Polym 2008;5:155–60. 2012;11:53–7.

[283] Zschech D, Milenin AP, Scholz R, Hillebrand R, Sun Y, Uhlmann P, [305] Pitet LM, Amendt MA, Hillmyer MA. Nanoporous linear polyethy-

Stamm M, Steinhart M, Gösele U. Transfer of sub-30-nm patterns lene from a block polymer precursor. J Am Chem Soc 2010;132:

from templates based on supramolecular assemblies. Macro- 8230–1.

molecules 2007;40:7752–4. [306] Uehara H, Kakiage M, Sekiya M, Yamagishi T, Yamanobe T, Nakajima

[284] Nandan B, Vyas MK, Böhme M, Stamm M. Composition-dependent K, Watanabe T, Nomura K, Hase K, Matsuda M. Novel design solving

morphological transitions and pathways in switching of ﬁne struc- the conductivity vs. water-uptake trade-off for polymer electrolyte

ture in thin ﬁlms of block copolymer supramolecular assemblies. membrane by bicontinuous crystalline/amorphous morphology of

Macromolecules 2010;43:2463–73. block copolymer. Macromolecules 2009;42:7627–30.

[285] Tokarev I, Krenek R, Burkov Y, Schmeisser D, Sidorenko A, Minko [307] Uehara H, Yoshida T, Kakiage M, Yamanobe T, Komoto T, Nomura

S, Stamm M. Microphase separation in thin ﬁlms of poly(styrene- K, Nakajima K, Matsuda M. Nanoporous polyethylene ﬁlm pre-

block-4-vinylpyridine) copolymer-2-(4 -hydroxybenzeneazo) pared from bicontinuous crystalline/amorphous structure of block

benzoic acid assembly. Macromolecules 2004;38:507–16. copolymer precursor. Macromolecules 2006;39:3971–4.

1718 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

[308] Uehara H, Kakiage M, Sekiya M, Sakuma D, Yamonobe T, Takano [329] Wang YQ, Wang T, Su YL, Peng FB, Wu H, Jiang ZY. Remarkable

N, Barraud A, Meurville E, Ryser P. Size-selective diffusion in reduction of irreversible fouling and improvement of the perme-

nanoporous but ﬂexible membranes for glucose sensors. ACS Nano ation properties of poly(ether sulfone) ultraﬁltration membranes

2009;3:924–32. by blending with Pluronic F127. Langmuir 2005;21:11856–62.

[309] Li L, Szewczykowski P, Clausen LD, Hansen KM, Jonsson GE, Ndoni S. [330] Wang YQ, Su YL, Sun Q, Ma XO, Ma XC, Jiang ZY. Improved per-

Ultraﬁltration by gyroid nanoporous polymer membranes. J Membr meation performance of Pluronic F127-polyethersulfone blend

Sci 2011;384:126–35. ultraﬁltration membranes. J Membr Sci 2006;282:44–51.

[310] Li L, Schulte L, Clausen LD, Hansen KM, Jonsson GE, Ndoni S. [331] Wang YQ, Su YL, Ma XL, Sun Q, Jiang ZY. Pluronic polymers

Gyroid nanoporous membranes with tunable permeability. ACS and polyethersulfone blend membranes with improved fouling-

Nano 2011;5:7754–66. resistant ability and ultraﬁltration performance. J Membr Sci

[311] Rangou S, Buhr K, Filiz V, Clodt JI, Lademann B, Hahn J, Jung A, Abetz 2006;283:440–7.

V. Self-organized isoporous membranes with tailored pore sizes. J [332] Lv CL, Su YL, Wang YQ, Ma XL, Sun Q, Jiang ZY. Enhanced perme-

Membr Sci 2014;451:266–75. ation performance of cellulose acetate ultraﬁltration membrane by

[312] Karunakaran M, Nunes SP, Qiu X, Yu H, Peinemann KV. Iso- incorporation of Pluronic F127. J Membr Sci 2007;294:68–74.

porous PS-b-PEO ultraﬁltration membranes via self-assembly [333] Shi Q, Ye SJ, Kristalyn C, Su YL, Jiang ZY, Chen Z. Probing molecular-

and water-induced phase separation. J Membr Sci 2014;453: level surface structures of polyethersulfone/Pluronic F127 blends

471–7. using sum-frequency generation vibrational spectroscopy. Lang-

[313] Dorin RM, Phillip WA, Sai H, Werner J, Elimelech M, Wiesner U. muir 2008;24:7939–46.

Designing block copolymer architectures for targeted membrane [334] Zhao W, Su YL, Li C, Shi Q, Ning X, Jiang ZY. Fabrication of antifouling

performance. Polymer 2014;55:347–53. polyethersulfone ultraﬁltration membranes using Pluronic F127

[314] Shannon MA, Bohn PW, Elimelech M, Georgiadis JG, Marinas BJ, as both surface modiﬁer and pore-forming agent. J Membr Sci

Mayes AM. Science and technology for water puriﬁcation in the 2008;318:405–12.

coming decades. Nature 2008;452:301–10. [335] Chen WJ, Peng JM, Su YL, Zheng LL, Wang LJ, Jiang ZY. Separation of

[315] Ma XL, Su YL, Sun Q, Wang YQ, Jiang ZY. Preparation of protein- oil/water emulsion using Pluronic F127 modiﬁed polyethersulfone

adsorption-resistant polyethersulfone ultraﬁltration membranes ultraﬁltration membranes. Sep Purif Technol 2009;66:591–7.

through surface segregation of amphiphilic comb copolymer. J [336] Li B, Zhao W, Su YL, Jiang ZY, Dong X, Liu WP. Enhanced desul-

Membr Sci 2007;292:116–24. furization performance and swelling resistance of asymmetric

[316] Su YL, Li C, Zhao W, Shi Q, Wang HJ, Jiang ZY, Zhu SP. Modiﬁcation hydrophilic pervaporation membrane prepared through surface

of polyethersulfone ultraﬁltration membranes with phosphoryl- segregation technique. J Membr Sci 2009;326:556–63.

choline copolymer can remarkably improve the antifouling and [337] Peng JM, Su YL, Chen WJ, Shi Q, Jiang ZY. Effects of coagulation

permeation properties. J Membr Sci 2008;322:171–7. bath temperature on the separation performance and antifouling

[317] Hester JF, Banerjee P, Mayes AM. Preparation of protein-resistant property of poly(ether sulfone) ultraﬁltration membranes. Ind Eng

surfaces on poly(vinylidene ﬂuoride) membranes via surface seg- Chem Res 2010;49:4858–64.

regation. Macromolecules 1999;32:1643–50. [338] Zhang Y, Su YL, Chen WJ, Peng JM, Dong YN, Jiang ZY, Liu HZ.

[318] Hester JF, Mayes AM. Design and performance of foul-resistant Appearance of poly(ethylene oxide) segments in the polyamide

poly(vinylidene ﬂuoride) membranes prepared in a single-step by layer for antifouling nanoﬁltration membranes. J Membr Sci

surface segregation. J Membr Sci 2002;202:119–35. 2011;382:300–7.

[319] Liu F, Xu YY, Zhu BK, Zhang F, Zhu LP. Preparation of hydrophilic [339] Susanto H, Ulbricht M. Characteristics, performance and stability

and fouling resistant poly(vinylidene fluoride) hollow fiber mem- of polyethersulfone ultrafiltration membranes prepared by phase

branes. J Membr Sci 2009;345:331–9. separation method using different macromolecular additives. J

[320] Shi JL, Fang LF, Li H, Liang ZY, Zhu BK, Zhu LP. Enhanced performance Membr Sci 2009;327:125–35.

of modiﬁed HDPE separators generated from surface enrichment [340] Susanto H, Stahra N, Ulbricht M. High performance polyether-

of polyether chains for lithium ion secondary battery. J Membr Sci sulfone microﬁltration membranes having high ﬂux and stable

2013;429:355–63. hydrophilic property. J Membr Sci 2009;342:153–64.

[321] Yi Z, Zhu LP, Xu YY, Li XL, Yu JZ, Zhu BK. F127-based multi- [341] Venault A, Chang Y, Wang DM, Lai JY. Surface anti-biofouling

block copolymer additives with poly(N,N-dimethylamino-2-ethyl control of PEGylated poly(vinylidene ﬂuoride) membranes

methacrylate) end chains: the hydrophilicity and stimuli- via vapor-induced phase separation processing. J Membr Sci

responsive behavior investigation in polyethersulfone membranes 2012;423–424:53–64.

modiﬁcation. J Membr Sci 2010;364:34–42. [342] Venault A, Chang Y, Wang DM, Bouyer D, Higuchi A, Lai JY.

[322] Zhao YH, Zhu BK, Kong L, Xu YY. Improving hydrophilicity and PEGylation of anti-biofouling polysulfone membranes via liquid-

protein resistance of poly(vinylidene ﬂuoride) membranes by and vapor-induced phase separation processing. J Membr Sci

blending with amphiphilic hyperbranched-star polymer. Langmuir 2012;403–404:47–57.

2007;23:5779–86. [343] Chen WJ, Su YL, Peng JM, Zhao XT, Jiang ZY, Dong YN, Zhang Y, Liang

[323] Zhao YH, Qian YL, Pang DX, Zhu BK, Xu YY. Porous membranes YG, Liu JZ. Efﬁcient wastewater treatment by membranes through

modiﬁed by hyperbranched polymers. II: Effect of the arm length constructing tunable antifouling membrane surfaces. Environ Sci

of amphiphilic hyperbranched-star polymers on the hydrophilicity Technol 2011;45:6545–52.

and protein resistance of poly(vinylidene ﬂuoride) membranes. J [344] Zhao XT, Su YL, Chen WJ, Peng JM, Jiang ZY. PH-responsive

Membr Sci 2007;304:138–47. and fouling-release properties of PES ultraﬁltration membranes

[324] Zhao YH, Zhu BK, Ma XT, Xu YY. Porous membranes modiﬁed by modiﬁed by multi-functional block-like copolymers. J Membr Sci

hyperbranched polymers. I: Preparation and characterization of 2011;382:222–30.

PVDF membrane using hyperbranched polyglycerol as additive. J [345] Zhao XT, Su YL, Li YF, Zhang RN, Zhao JJ, Jiang ZY. Engineer-

Membr Sci 2007;290:222–9. ing amphiphilic membrane surfaces based on PEO and PDMS

[325] Zhao YH, Qian YL, Zhu BK, Xu YY. Modiﬁcation of porous segments for improved antifouling performances. J Membr Sci

poly(vinylidene ﬂuoride) membrane using amphiphilic polymers 2014;450:111–23.

with different structures in phase inversion process. J Membr Sci [346] Chen WJ, Su YL, Peng JM, Dong YN, Zhao XT, Jiang ZY. Engineering

2008;310:567–76. a robust, versatile amphiphilic membrane surface through forced

[326] Yi Z, Zhu LP, Xu YY, Zhao YF, Ma XT, Zhu BK. Polysulfone- surface segregation for ultralow ﬂux-decline. Adv Funct Mater

based amphiphilic polymer for hydrophilicity and fouling-resistant 2011;21:191–8.

modiﬁcation of polyethersulfone membranes. J Membr Sci [347] Liu K, Jiang L. Bio-inspired design of multiscale structures for func-

2010;365:25–33. tion integration. Nano Today 2011;6:155–75.

[327] Zhu LP, Xu L, Zhu BK, Feng YX, Xu YY. Preparation and char- [348] Xue Z, Cao Y, Liu N, Feng L, Jiang L. Special wettable materials for

acterization of improved fouling-resistant PPESK ultraﬁltration oil/water separation. J Mater Chem A 2014;2:2445.

membranes with amphiphilic PPESK-graft-PEG copolymers as [349] Wu W, Zhu Q, Qing F, Han CC. Water repellency on a ﬂuorine-

additives. J Membr Sci 2007;294:196–206. containing polyurethane surface: toward understanding the

[328] Zhu LP, Yi Z, Liu F, Wei XZ, Zhu BK, Xu YY. Amphiphilic graft surface self-cleaning effect. Langmuir 2008;25:17–20.

copolymers based on ultrahigh molecular weight poly(styrene- [350] Wang S, Li Y, Fei X, Sun M, Zhang C, Yang Q, Hong X. Prepara-

alt-maleic anhydride) with poly(ethylene glycol) side chains for tion of a durable superhydrophobic membrane by electrospinning

surface modiﬁcation of polyethersulfone membranes. Eur Polym J poly(vinylidene ﬂuoride) (PVDF) mixed with epoxy–siloxane mod-

2008;44:1907–14. iﬁed SiO2 nanoparticles: a possible route to superhydrophobic

J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720 1719

surfaces with low water sliding angle and high water contact angle. [375] Li YF, Su YL, Zhao XT, He X, Zhang RN, Zhao JJ, Fan XC,

J Colloid Interface Sci 2011;359:380–8. Jiang ZY. Antifouling, high-ﬂux nanoﬁltration membranes enabled

[351] Wang X, Ding B, Yu J, Wang M. Engineering biomimetic super- by dual functional polydopamine. ACS Appl Mater Interfaces

hydrophobic surfaces of electrospun nanomaterials. Nano Today 2014;6:5548–57.

2011;6:510–30. [376] Xue Z, Wang S, Lin L, Chen L, Liu M, Feng L, Jiang L. A novel superhy-

[352] Han D, Steckl AJ. Superhydrophobic and oleophobic ﬁbers by coax- drophilic and underwater superoleophobic hydrogel-coated mesh

ial electrospinning. Langmuir 2009;25:9454–62. for oil/water separation. Adv Mater 2011;23:4270–3.

[353] Lim HS, Baek JH, Park K, Shin HS, Kim J, Cho JH. Multifunctional [377] Xue B, Gao L, Hou Y, Liu Z, Jiang L. Temperature controlled water/oil

hybrid fabrics with thermally stable superhydrophobicity. Adv wettability of a surface fabricated by a block copolymer: application

Mater 2010;22:2138–41. as a dual water/oil on–off switch. Adv Mater 2013;25:273–7.

[354] Ma M, Hill RM, Lowery JL, Fridrikh SV, Rutledge GC. Electro- [378] Zhang S, Lu F, Tao L, Liu N, Gao C, Feng L, Wei Y. Bio-inspired anti-

spun poly(styrene-block-dimethylsiloxane) block copolymer ﬁbers oil-fouling chitosan-coated mesh for oil/water separation suitable

exhibiting superhydrophobicity. Langmuir 2005;21:5549–54. for broad pH range and hyper-saline environments. ACS Appl Mater

[355] Kao TH, Chen JK, Cheng CC, Su CI, Chang FC. Low-surface-free- Interfaces 2013;5:11971–6.

energy polybenzoxazine/polyacrylonitrile ﬁbers for biononfouling [379] Zhang W, Zhu Y, Liu X, Wang D, Li J, Jiang L, Jin J. Salt-induced

membrane. Polymer 2013;54:258–68. fabrication of superhydrophilic and underwater superoleophobic

[356] Hardman SJ, Muhamad-Sarih N, Riggs HJ, Thompson RL, Rigby PAA-g-PVDF membranes for effective separation of oil-in-water

J, Bergius WNA, Hutchings LR. Electrospinning superhydrophobic emulsions. Angew Chem Int Ed Engl 2014;53:856–60.

ﬁbers using surface segregating end-functionalized polymer addi- [380] McCloskey BD, Park HB, Ju H, Rowe BW, Miller DJ, Freeman BD. A

tives. Macromolecules 2011;44:6461–70. bioinspired fouling-resistant surface modiﬁcation for water puriﬁ-

[357] Shang Y, Si Y, Raza A, Yang L, Mao X, Ding B, Yu J. An in situ poly- cation membranes. J Membr Sci 2012;413–414:82–90.

merization approach for the synthesis of superhydrophobic and [381] Miller DJ, Kasemset S, Wang L, Paul DR, Freeman BD. Constant

superoleophilic nanofibrous membranes for oil–water separation. flux crossflow filtration evaluation of surface-modified fouling-

Nanoscale 2012;4:7847–54. resistant membranes. J Membr Sci 2014;452:171–83.

[358] Tang X, Si Y, Ge J, Ding B, Liu L, Zheng G, Luo W, Yu J. In situ [382] Arena JT, McCloskey B, Freeman BD, McCutcheon JR. Surface mod-

polymerized superhydrophobic and superoleophilic nanofibrous ification of thin film composite membrane support layers with

membranes for gravity driven oil–water separation. Nanoscale polydopamine: enabling use of reverse osmosis membranes in

2013;5:11657–64. pressure retarded osmosis. J Membr Sci 2011;375:55–62.

[359] Wang L, Yang S, Wang J, Wang C, Chen L. Fabrication of [383] Li X, Wang C, Yang Y, Wang X, Zhu M, Hsiao BS. Dual-biomimetic

superhydrophobic TPU ﬁlm for oil–water separation based on elec- superhydrophobic electrospun polystyrene nanoﬁbrous mem-

trospinning route. Mater Lett 2011;65:869–72. branes for membrane distillation. ACS Appl Mater Interfaces

[360] Huang M, Si Y, Tang X, Zhu Z, Ding B, Liu L, Zheng G, Luo W, Yu 2014;6:2423–30.

J. Gravity driven separation of emulsiﬁed oil–water mixtures uti- [384] Liao Y, Wang R, Fane AG. Engineering superhydrophobic surface on

lizing in situ polymerized superhydrophobic and superoleophilic poly(vinylidene ﬂuoride) nanoﬁber membranes for direct contact

nanoﬁbrous membranes. J Mater Chem A 2013;1:14071–4. membrane distillation. J Membr Sci 2013;440:77–87.

[361] Asmatulu R, Ceylan M, Nuraje N. Study of superhydrophobic [385] Razmjou A, Ariﬁn E, Dong G, Mansouri J, Chen V. Superhydrophobic

electrospun nanocomposite ﬁbers for energy systems. Langmuir modiﬁcation of TiO2 nanocomposite PVDF membranes for applica-

2010;27:504–7. tions in membrane distillation. J Membr Sci 2012;415–416:850–63.

[362] Zhu Y, Zhang J, Zheng Y, Huang Z, Feng L, Jiang L. Stable, super- [386] Venault A, Chang Y, Yang HS, Lin PY, Shih YJ, Higuchi A. Sur-

hydrophobic, and conductive polyaniline/polystyrene ﬁlms for face self-assembled zwitterionization of poly(vinylidene ﬂuoride)

corrosive environments. Adv Funct Mater 2006;16:568–74. microﬁltration membranes via hydrophobic-driven coating for

[363] Wang N, Zhao Y, Jiang L. Low-cost, thermoresponsive wettability improved blood compatibility. J Membr Sci 2014;454:253–63.

of surfaces: poly(n-isopropylacrylamide)/polystyrene composite [387] Sun G, Chung TS, Jeyaseelan K, Armugam A. Stabilization and

ﬁlms prepared by electrospinning. Macromol Rapid Commun immobilization of aquaporin reconstituted lipid vesicles for water

2008;29:485–9. puriﬁcation. Colloids Surf B 2013;102:466–71.

[364] Jin H, Kettunen M, Laiho A, Pynnönen H, Paltakari J, Marmur [388] Wang H, Chung TS, Tong YW, Jeyaseelan K, Armugam A, Duong

A, Ikkala O, Ras RHA. Superhydrophobic and superoleophobic HHP, Fu F, Seah H, Yang J, Hong M. Mechanically robust and

nanocellulose aerogel membranes as bioinspired cargo carriers on highly permeable Aquaporin Z biomimetic membranes. J Membr

water and oil. Langmuir 2011;27:1930–4. Sci 2013;434:130–6.

[365] Ma M, Mao Y, Gupta M, Gleason KK, Rutledge GC. Superhydrophobic [389] Wang H, Chung TS, Tong YW. Study on water transport through a

fabrics produced by electrospinning and chemical vapor deposi- mechanically robust Aquaporin Z biomimetic membrane. J Membr

tion. Macromolecules 2005;38:9742–8. Sci 2013;445:47–52.

[366] Ma M, Gupta M, Li Z, Zhai L, Gleason KK, Cohen RE, Rubner MF, [390] Zhao Y, Vararattanavech A, Li X, Hélixnielsen C, Vissing T, Torres J,

Rutledge GC. Decorated electrospun ﬁbers exhibiting superhy- Wang R, Fane AG, Tang CY. Effects of proteoliposome composition

drophobicity. Adv Mater 2007;19:255–9. and draw solution types on separation performance of aquaporin-

[367] Tuteja A, Choi W, Ma ML, Mabry JM, Mazzella SA, Rutledge GC, based proteoliposomes: implications for seawater desalination

McKinley GH, Cohen RE. Designing superoleophobic surfaces. Sci- using aquaporin-based biomimetic membranes. Environ Sci Tech-

ence 2007;318:1618–22. nol 2013;47:1496–503.

[368] Kota AK, Kwon G, Choi W, Mabry JM, Tuteja A. Hygro-responsive [391] Li X, Wang R, Wicaksana F, Tang C, Torres J, Fane AG. Preparation

membranes for effective oil–water separation. Nat Commun of high performance nanoﬁltration (NF) membranes incorporated

2012;3:1025. with aquaporin Z. J Membr Sci 2014;450:181–8.

[369] Kwon G, Kota AK, Li Y, Sohani A, Mabry JM, Tuteja A. On-demand [392] Xie W, He F, Wang B, Chung TS, Jeyaseelan K, Armugam A, Tong

separation of oil–water mixtures. Adv Mater 2012;24:3666–71. YW. An aquaporin-based vesicle-embedded polymeric membrane

[370] Chhatre SS, Tuteja A, Choi W, Revaux Al, Smith D, Mabry JM, for low energy water ﬁltration. J Mater Chem A 2013;1:7592–600.

McKinley GH, Cohen RE. Thermal annealing treatment to achieve [393] Holt JK, Park HG, Wang Y, Stadermann M, Artyukhin AB, Grig-

switchable and reversible oleophobicity on fabrics. Langmuir oropoulos CP, Noy A, Bakajin O. Fast mass transport through

2009;25:13625–32. sub-2-nanometer carbon nanotubes. Science 2006;312:1034–7.

[371] Li J, Shi L, Chen Y, Zhang Y, Guo Z, Su B, Liu W. Stable superhydropho- [394] Lin H, Zhao C, Ma W, Li H, Na H. Low water swelling and

bic coatings from thiol-ligand nanocrystals and their application in high methanol resistant proton exchange membrane fabricated by

oil/water separation. J Mater Chem 2012;22:9774–81. cross-linking of multilayered polyelectrolyte complexes. J Membr

[372] Zhang W, Shi Z, Zhang F, Liu X, Jin J, Jiang L. Superhydrophobic Sci 2009;345:242–8.

and superoleophilic PVDF membranes for effective separation of [395] Zhao C, Lin H, Zhang Q, Na H. Layer-by-layer self-assembly of

water-in-oil emulsions with high ﬂux. Adv Mater 2013;25:2071–6. polyaniline on sulfonated poly(arylene ether ketone) membrane

[373] Yang J, Zhang Z, Xu X, Zhu X, Men X, Zhou X. with high proton conductivity and low methanol crossover. Int J

Superhydrophilic–superoleophobic coatings. J Mater Chem Hydrogen Energy 2010;35:10482–8.

2012;22:2834–7. [396] Park MJ, Downing KH, Jackson A, Gomez ED, Minor AM, Cookson D,

[374] Zhao XT, Su YL, Chen WJ, Peng JM, Jiang ZY. Grafting perﬂuoroalkyl Weber AZ, Balsara NP. Increased water retention in polymer elec-

groups onto polyacrylonitrile membrane surface for improved foul- trolyte membranes at elevated temperatures assisted by capillary

ing release property. J Membr Sci 2012;415–416:824–34. condensation. Nano Lett 2007;7:3547–52.

1720 J. Zhao et al. / Progress in Polymer Science 39 (2014) 1668–1720

[397] Moore HD, Saito T, Hickner MA. Morphology and transport prop- [408] Csernica J, Baddour RF, Cohen RE. Gas permeability of a

erties of midblock-sulfonated triblock copolymers. J Mater Chem polystyrene/polybutadiene block copolymer possessing a misori-

2010;20:6316–21. ented lamellar morphology. Macromolecules 1989;22:1493–6.

[398] Yameen B, Kaltbeitzel A, Langner A, Duran H, Muller F, Gosele U, [409] Drzala PL, Halasab AF, Koﬁnasa P. Microstructure orientation

Azzaroni O, Knoll W. Facile large-scale fabrication of proton con- and nanoporous gas transport in semicrystalline block copolymer

ducting channels. J Am Chem Soc 2008;130:13140–4. membranes. Polymer 2000;41:4671–7.

[399] Moghaddam S, Pengwang E, Jiang YB, Garcia AR, Burnett DJ, Brinker [410] Bao L, Trachtenberg MC. Facilitated transport of CO2 across a liquid

CJ, Masel RL, Shanno MA. An inorganic–organic proton exchange membrane: comparing enzyme, amine, and alkaline. J Membr Sci

membrane for fuel cells with a controlled nanoscale pore structure. 2006;280:330–4.

Nat Nanotechnol 2010;5:230–6. [411] Favre N, Pierre AC. Synthesis and behaviour of hybrid polymer–

[400] Yamaguchi T, Zhou H, Nakazawa S, Hara N. An extremely low silica membranes made by sol gel process with adsorbed carbonic

methanol crossover and highly durable aromatic pore-ﬁlling elec- anhydrase enzyme, in the capture of CO2. J Sol–Gel Sci Technol

trolyte membrane for direct methanol fuel cells. Adv Mater 2011;60:177–88.

2007;19:592–6. [412] Zhang YT, Zhang L, Chen HL, Zhang HM. Selective separation of

[401] Vane LM. A review of pervaporation for product recovery from low concentration CO2 using hydrogel immobilized CA enzyme

biomass fermentation processes. J Chem Technol Biotechnol based hollow ﬁber membrane reactors. Chem Eng Sci 2010;65:

2005;80:603–29. 3199–207.

[402] Raisi A, Aroujalian A. Aroma compound recovery by hydropho- [413] Yao K, Wang Z, Wang J, Wang S. Biomimetic material-poly(N-

bic pervaporation: the effect of membrane thickness and coupling vinylimidazole)-zinc complex for CO2 separation. Chem Commun

phenomena. Sep Purif Technol 2011;82:53–62. 2012;48:1766–8.

[403] Lu F, Kong Y, Lv H, Yang J. The removal of thiophene from [414] Ran F, Nie S, Zhao W, Li J, Su B, Sun S, Zhao C. Biocompati-

n-heptane/thiophene mixtures by polyethylene glycol-block- bility of modiﬁed polyethersulfone membranes by blending an

polyacrylonitrile membranes. Pet Sci Technol 2012;30:1232–8. amphiphilic triblock co-polymer of poly(vinyl pyrrolidone)-b-

[404] Freeman BD. Basis of permeability/selectivity tradeoff rela- poly(methyl methacrylate)-b-poly(vinyl pyrrolidone). Acta Bio-

tions in polymeric gas separation membranes. Macromolecules mater 2011;7:3370–81.

1999;32:375–80. [415] Wang ZG, Wan LS, Xu ZK. Surface engineerings of polyacrylonitrile-

[405] Lu F, Kong Y, Lv H, Yang J, Feng Z. The correlation between sol- based asymmetric membranes towards biomedical applications:

vent treatment and the microstructure of PAN-b-PEG copolymer an overview. J Membr Sci 2007;304:8–23.

membranes. Polym J 2011;43:378–84. [416] Ma L, Qin H, Cheng C, Xia Y, He C, Nie C, Wang L, Zhao C.

[406] MacDowell N, Florin N, Buchard A, Hallett J, Galindo A, Jackson G, Mussel-inspired self-coating at macro-interface with improved

Adjiman CS, Williams CK, Shah N, Fennell P. An overview of CO2 biocompatibility and bioactivity via dopamine grafted heparin-like

capture technologies. Energy Environ Sci 2010;3:1645–69. polymers and heparin. J Mater Chem B 2014;2:363–75.

[407] Yang HQ, Xu ZH, Fan MH, Gupta R, Slimane RB, Bland AE, Wright [417] Gao A, Liu F, Xue L. Preparation and evaluation of heparin-

I. Progress in carbon dioxide separation and capture: a review. J immobilized poly(lactic acid) (PLA) membrane for hemodialysis.

Environ Sci 2008;20:14–27. J Membr Sci 2014;452:390–9.