DOCSLIB.ORG

Review Article Importance of Molecular Interactions in Colloidal Dispersions

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Review Article Importance of Molecular Interactions in Colloidal Dispersions Hindawi Publishing Corporation Advances in Condensed Matter Physics Volume 2015, Article ID 683716, 8 pages http://dx.doi.org/10.1155/2015/683716 Review Article Importance of Molecular Interactions in Colloidal Dispersions R. López-Esparza,1,2 M. A. Balderas Altamirano,1 E. Pérez,1 and A. Gama Goicochea1,3 1 Instituto de F´ısica, Universidad Autonoma´ de San Luis Potos´ı, 78290 San Luis Potos´ı, SLP, Mexico 2Departamento de F´ısica, Universidad de Sonora, 83000 Hermosillo, SON, Mexico 3Innovacion´ y Desarrollo en Materiales Avanzados A. C., Grupo Polynnova, 78211 San Luis Potos´ı, SLP, Mexico Correspondence should be addressed to A. Gama Goicochea; [email protected] Received 21 May 2015; Accepted 2 August 2015 Academic Editor: Jan A. Jung Copyright © 2015 R. Lopez-Esparza´ et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We review briefly the concept of colloidal dispersions, their general properties, and some of their most important applications, as well as the basic molecular interactions that give rise to their properties in equilibrium. Similarly, we revisit Brownian motion and hydrodynamic interactions associated with the concept of viscosity of colloidal dispersion. It is argued that the use of modern research tools, such as computer simulations, allows one to predict accurately some macroscopically measurable properties by solving relatively simple models of molecular interactions for a large number of particles. Lastly, as a case study, we report the prediction of rheological properties of polymer brushes using state-of-the-art, coarse-grained computer simulations, which are in excellent agreement with experiments. 1. Introduction become an international business that generates billions of dollars annually; therefore there are current basic and applied British physicist Thomas Graham in 1861 invented the term research efforts devoted to their study and optimization [4]. “colloid” from the Greek word kolla,meaningglue.Graham The process of removing solid particles from waste water to tried to classify the behavior of various chemicals with respect make it drinkable again, that is, removing the solute from the to their diffusion using membranes [1]. Over time, it has solvent, is a major problem today, intimately related to public become clear that colloids should not be considered as a spe- health and environmental protection issues. Many industrial cialclassofchemicalsbutrathercorrespondtostatesinwhich processes generate waste in the form of colloidal suspensions, matter is associated, naturally or artificially, due to some which must be treated and purified before being released physical division. In general, colloidal systems are composed to the environment [5]. Moreover, colloidal dispersions are of a continuous medium and a dispersed phase. The case that important in academy, and their stability is the result of the concerns us is that the colloidal suspension is one in which delicate balance of attractive and repulsive forces [6], which thecontinuousmediumisintheliquidstate(called“solvent”) give rise to complex phenomena of many-body interactions whereas the dispersed phase consists of solid particles (called that cannot be fully understood using ab initio theories except the“solute”).Thesizeofthesoluteparticlesrangesfrom for some simplified models. Hence, models have been pro- 10 nm to 1 m approximately [2]. Some common examples of posed based on effective interactions and computer simula- colloidal solutions are paints, inks, wastewater, and ceramics tion solutions [7]. [3]. Of course, there are colloidal systems in which the con- tinuous medium is solid or gaseous and the dispersed phase is a liquid or a gas, but these systems are not the focus of this 2. Basic Interactions between work and therefore shall not be discussed. The present day Colloidal Particles importance of colloidal suspensions arises from the impact of their industrial applications in contemporary societies. The dominant attractive interaction in suspensions of col- A familiar example of a colloidal suspension, paints, has loidal particles is the van der Waals (vdW) interaction, which 2 Advances in Condensed Matter Physics ≈≈ Figure 1: Model of interaction between colloidal particles of radius and solvent. The leftmost image represents a dispersion of colloidal particles (in red), coated with polymers, which are dispersed with polymer chains (in yellow). The central image illustrates the size difference between the colloids (in gray) and the solvent molecules (in cyan). Because of this size difference, colloidal particles can be considered as planar walls when modeling their interactions with the solvent, as shown in the rightmost image. is nevertheless short-ranged. It arises from the averaged + + + + + + + quantum fluctuations of the electric dipoles on the surface of + − − − particles [6]; it is a pair interaction that can be written as − + + + − − − − − + 2 − + − () =− ( ) , (1) + − vdW 12 − + + − − − − + − where is the so-called Hamaker constant, is the radius of − + − − + + + the colloidal particles (see Figure 1) which are assumed to be + + + identical, and is the distance between them. The value of + depends on the nature of both the solvent and the colloidal Figure 2: Two colloidal particles (large spheres) in suspension, particles [6]. showing the distribution of ions (small circles) around them, which Electric charges are usually present on the surface of give rise to screening of the long range electrostatic interaction, colloids as well, and such basic interaction must also be yielding (2). accounted for when studying colloidal suspensions. One should recognize that this interaction is expected to be differ- ent from the bare Coulomb interaction, because the colloidal particles are dispersed in a liquid medium, which modifies it. Overbeek), see the solid line in Figure 3. A salient aspect of A useful expression for the electrostatic interaction in col- the DLVO potential is that it develops a repulsive barrier loidal suspensions, , is [6]: of height max at certain relative position max between ≫ 2 the centers of mass of the colloids. When max , () =4 0 exp (−) , (2) > 2 + / those particles whose relative separations are max are very unlikely to agglomerate, due to Brownian motion for where is the dielectic constant of the liquid medium, 0 example. The colloidal suspension is, therefore, kinetically is the electrical potential on the colloids’ surfaces, and is stable. When the separation between the particles is relatively known as the Debye-Huckel¨ constant. The latter is defined as short, they are likely to fall into the primary minimum dom- [6]: inated by the vdW attraction (1), leading to the irreversible 2 ∑ 2 2 flocculation of the suspension. There is, of course, a contin- =( ) , (3) uous relative-separation distance distribution of the particles at any finite temperature, with some of those distances being large enough to avoid agglomeration. However, the peak of where is the fundamental unit of charge; is the concen- such distribution will be at distances where the energy is at tration and the valence of ions of type ,and is the its minimum, and as time progresses more and more particles thermal energy. Equation (3) represents the inverse of the characteristic decay length of the screened electrostatic inter- will fall into that minimum energy state. Given a large enough action; see Figure 2, which should be expected to depend on period of time all particles will move toward their global the concentration of electric charges in the medium. Both the minimum energy state, leading to the flocculation of the vdW and electrostatic interactions are illustrated in Figure 3 suspension, although the energy barrier max may be large by dotted lines. enough to prevent such event from happening during a long Since both of these interactions are usually present in enough period of time for the suspension to be practically most colloidal suspensions, the complex interplay between stable. To further increase the kinetic stability period of them has been studied for several decades, giving rise to the suspension, polymer chains are typically grafted on the a compounded potential interaction function, known as colloids’ surfaces, which introduces an additional repulsive the DLVO potential (after Derjaguin, Landau, Verwey and force at short interparticle distances [6]. Advances in Condensed Matter Physics 3 U(r) between particles coated with polymeric brushes on the - axis as a function of the distance between the particles UE(r) (-axis), illustrates how repulsion appears when distances Repulsive between polymeric brushes are short (leftmost curve). By barrier, Emax increasing the length of the polymer chains, maintaining the fixed number of chains per unit area on the particles, the repulsion also increases (middle curve). Finally, if the length of the chains is kept fixed but the grafting density of chains per particle increases, the repulsion is even higher (rightmost curve). 0 S r max 3. Hydrodynamic and Brownian Interactions in Colloidal Suspensions U (r) So far we have discussed some of the most important interac- Primary vdW tions in colloidal suspensions in equilibrium, that is, when minimum there are no external forces applied to the system, so that none of the thermodynamic properties are time dependent. When an external
Load more

Recommended publications
  • Plasmofluidic Single-Molecule Surface-Enhanced Raman
    ARTICLE Received 24 Feb 2014 | Accepted 9 Jun 2014 | Published 7 Jul 2014 DOI: 10.1038/ncomms5357 Plasmofluidic single-molecule surface-enhanced Raman scattering from dynamic assembly of plasmonic nanoparticles Partha Pratim Patra1, Rohit Chikkaraddy1, Ravi P.N. Tripathi1, Arindam Dasgupta1 & G.V. Pavan Kumar1 Single-molecule surface-enhanced Raman scattering (SM-SERS) is one of the vital applications of plasmonic nanoparticles. The SM-SERS sensitivity critically depends on plasmonic hot-spots created at the vicinity of such nanoparticles. In conventional fluid-phase SM-SERS experiments, plasmonic hot-spots are facilitated by chemical aggregation of nanoparticles. Such aggregation is usually irreversible, and hence, nanoparticles cannot be re-dispersed in the fluid for further use. Here, we show how to combine SM-SERS with plasmon polariton-assisted, reversible assembly of plasmonic nanoparticles at an unstructured metal–fluid interface. One of the unique features of our method is that we use a single evanescent-wave optical excitation for nanoparticle assembly, manipulation and SM-SERS measurements. Furthermore, by utilizing dual excitation of plasmons at metal–fluid interface, we create interacting assemblies of metal nanoparticles, which may be further harnessed in dynamic lithography of dispersed nanostructures. Our work will have implications in realizing optically addressable, plasmofluidic, single-molecule detection platforms. 1 Photonics and Optical Nanoscopy Laboratory, h-cross, Indian Institute of Science Education and Research, Pune 411008, India. Correspondence and requests for materials should be addressed to G.V.P.K. (email: [email protected]). NATURE COMMUNICATIONS | 5:4357 | DOI: 10.1038/ncomms5357 | www.nature.com/naturecommunications 1 & 2014 Macmillan Publishers Limited. All rights reserved.
    [Show full text]
  • Generation and Stability of Size-Adjustable Bulk Nanobubbles
    www.nature.com/scientificreports OPEN Generation and Stability of Size-Adjustable Bulk Nanobubbles Based on Periodic Pressure Received: 10 September 2018 Accepted: 18 December 2018 Change Published: xx xx xxxx Qiaozhi Wang, Hui Zhao, Na Qi, Yan Qin, Xuejie Zhang & Ying Li Recently, bulk nanobubbles have attracted intensive attention due to the unique physicochemical properties and important potential applications in various felds. In this study, periodic pressure change was introduced to generate bulk nanobubbles. N2 nanobubbles with bimodal distribution and excellent stabilization were fabricated in nitrogen-saturated water solution. O2 and CO2 nanobubbles have also been created using this method and both have good stability. The infuence of the action time of periodic pressure change on the generated N2 nanobubbles size was studied. It was interestingly found that, the size of the formed nanobubbles decreases with the increase of action time under constant frequency, which could be explained by the diference in the shrinkage and growth rate under diferent pressure conditions, thereby size-adjustable nanobubbles can be formed by regulating operating time. This study might provide valuable methodology for further investigations about properties and performances of bulk nanobubbles. Nanobubbles are gaseous domains which could be found at the solid/liquid interface or in solution, known as surface nanobubbles (SNBs)1,2 and bulk nanobubbles (BNBs)3, respectively. For BNBs, generally recognized as spherical bubbles with the diameter of less than 1μm surrounded by liquid, though it has been observed frstly in 19814, the existence of long-lived BNBs is still a controversial subject as it is contrary to the classical theory5,6.
    [Show full text]
  • Colloidal Crystal: Emergence of Long Range Order from Colloidal Fluid
    Colloidal Crystal: emergence of long range order from colloidal fluid Lanfang Li December 19, 2008 Abstract Although emergence, or spontaneous symmetry breaking, has been a topic of discussion in physics for decades, they have not entered the set of terminologies for materials scientists, although many phenomena in materials science are of the nature of emergence, especially soft materials. In a typical soft material, colloidal suspension system, a long range order can emerge due to the interaction of a large number of particles. This essay will first introduce interparticle interactions in colloidal systems, and then proceed to discuss the emergence of order, colloidal crystals, and finally provide an example of applications of colloidal crystals in light of conventional molecular crystals. 1 1 Background and Introduction Although emergence, or spontaneous symmetry breaking, and the resultant collective behav- ior of the systems constituents, have manifested in many systems, such as superconductivity, superfluidity, ferromagnetism, etc, and are well accepted, maybe even trivial crystallinity. All of these phenonema, though they may look very different, share the same fundamental signature: that the property of the system can not be predicted from the microscopic rules but are, \in a real sense, independent of them. [1] Besides these emergent phenonema in hard condensed matter physics, in which the interaction is at atomic level, interactions at mesoscale, soft will also lead to emergent phenemena. Colloidal systems is such a mesoscale and soft system. This size scale is especially interesting: it is close to biogical system so it is extremely informative for understanding life related phenomena, where emergence is origin of life itself; it is within visible light wavelength, so that it provides a model system for atomic system with similar physics but probable by optical microscope.
    [Show full text]
  • Universality in Spectral Condensation Induja Pavithran1, Vishnu R
    www.nature.com/scientificreports OPEN Universality in spectral condensation Induja Pavithran1, Vishnu R. Unni2*, Alan J. Varghese3, D. Premraj3, R. I. Sujith3,4*, C. Vijayan1, Abhishek Saha2, Norbert Marwan4 & Jürgen Kurths4,5,6 Self-organization is the spontaneous formation of spatial, temporal, or spatiotemporal patterns in complex systems far from equilibrium. During such self-organization, energy distributed in a broadband of frequencies gets condensed into a dominant mode, analogous to a condensation phenomenon. We call this phenomenon spectral condensation and study its occurrence in fuid mechanical, optical and electronic systems. We defne a set of spectral measures to quantify this condensation spanning several dynamical systems. Further, we uncover an inverse power law behaviour of spectral measures with the power corresponding to the dominant peak in the power spectrum in all the aforementioned systems. During self-organization, an ordered pattern emerges from an initially disordered state. In dynamical systems, a pattern can be any regularly repeating arrangements in space, time or both1. For example, a laser emits random wave tracks like a lamp until the critical pump power, above which the laser emits light as a single coherent wave track with high-intensity2. A macroscopic change is observed in the laser system as a long-range pattern emerges in time. Another example is the Rayleigh–Bénard system. For lower temperature gradients, the fuid parcels move randomly. As the temperature gradient is increased, a rolling motion sets in and the fuid parcels behave coherently to form spatially extended patterns. Te initial random pattern can be regarded as a superposition of a variety of oscillatory modes and eventually some oscillatory modes dominate, resulting in the emergence of a spatio-temporal pattern3,4.
    [Show full text]
  • Surface Plasmon Resonance Study of the Purple Gold
    SURFACE PLASMON RESONANCE STUDY OF THE PURPLE GOLD (AuAl2) INTERMETALLIC, pH-RESPONSIVE FLUORESCENCE GOLD NANOPARTICLES, AND GOLD NANOSPHERE ASSEMBLY Panupon Samaimongkol Dissertation submitted to the faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy In Physics Hans D. Robinson, Chair Giti Khodaparast Chenggang Tao Webster Santos June 22, 2018 Blacksburg, Virginia Keywords: Surface plasmons (SPs), Localized surface plasmon resonances (LSPRs), Kretschmann configuration, Surface plasmon-enhanced fluorescence (PEF) spectroscopy, Self-Assembly, Nanoparticles Copyright 2018, Panupon Samaimongkol i SURFACE PLASMON RESONANCE STUDY OF THE PURPLE GOLD (AuAl2) INTERMETALLIC, pH-RESPONSIVE FLUORESCENCE GOLD NANOPARTICLES, AND GOLD NANOSPHERE ASSEMBLY Panupon Samaimongkol ABSTRACT (academic) In this dissertation, I have verified that the striking purple color of the intermetallic compound AuAl2, also known as purple gold, originates from surface plasmons (SPs). This contrasts to a previous assumption that this color is due to an interband absorption transition. The existence of SPs was demonstrated by launching them in thin AuAl2 films in the Kretschmann configuration, which enables us to measure the SP dispersion relation. I observed that the SP energy in thin films of purple gold is around 2.1 eV, comparable to previous work on the dielectric function of this material. Furthermore, SP sensing using AuAl2 also shows the ability to measure the change in the refractive index of standard sucrose solution. AuAl2 in nanoparticle form is also discussed in terms of plasmonic applications, where Mie scattering theory predicts that the particle bears nearly uniform absorption over the entire visible spectrum with an order magnitude higher absorption than efficient light-absorbing carbonaceous particle also known a carbon black.
    [Show full text]
  • Polymer Colloid Science
    Polymer Colloid Science Jung-Hyun Kim Ph. D. Nanosphere Process & Technology Lab. Department of Chemical Engineering, Yonsei University National Research Laboratory Project the financial support of the Korea Institute of S&T Evaluation and Planning (KISTEP) made in the program year of 1999 기능성 초미립자 공정연구실 Colloidal Aspects 기능성 초미립자 공정연구실 ♣ What is a polymer colloids ? . Small polymer particles suspended in a continuous media (usually water) . EXAMPLES - Latex paints - Natural plant fluids such as natural rubber latex - Water-based adhesives - Non-aqueous dispersions . COLLOIDS - The world of forgotten dimensions - Larger than molecules but too small to be seen in an optical microscope 기능성 초미립자 공정연구실 ♣ What does the term “stability/coagulation imply? . There is no change in the number of particles with time. A system is said to be colloidally unstable if collisions lead to the formation of aggregates; such a process is called coagulation or flocculation. ♣ Two ways to prevent particles from forming aggregates with one another during their colliding 1) Electrostatic stabilization by charged group on the particle surface - Origin of the charged group - initiator fragment (COOH, OSO3 , NH4, OH, etc) ionic surfactant (cationic or anionic) ionic co-monomer (AA, MAA, etc) 2) Steric stabilization by an adsorbed layer of some substance 3) Solvation stabilization 기능성 초미립자 공정연구실 기능성 초미립자 공정연구실 Stabilization Mechanism Electrostatic stabilization - Electrostatic stabilization Balancing the charge on the particle surface by the charges on small ions
    [Show full text]
  • Ways to Physically Separate a Mixture There Are 2 Types of Mixtures
    Mixtures 12 Mixtures Homogenous Compare Heterogeneous compounds and Suspension Mixtures. Colloid Solution Differentiate Solute/Solvent between solutions, suspensions, and colloids Comparing Mixtures and Compounds Mixtures Compounds Made of 2 or more substances Made of 2 or more substances physically combined chemically combined Substances keep their own properties Substances lose their own properties Can be separated by physical means Can be separated only by chemical means Have no definite chemical composition Have a definite chemical composition What method is used to separate mixtures Ways to physically separate a Mixture based on boiling • Distillation – uses boiling point point? • Magnet – uses magnetism What method is used • Centrifuge – uses density to separate mixtures based on density? • Filtering – separates large particles from smaller ones What method is used There are 2 types of mixtures: to separate mixtures (1) Heterogeneous Mixtures: the parts mixed together can still be based on particle size? distinguished from one another...NOT uniform in composition Give examples of a heterogeneous Examples: chicken soup, fruit salad, dirt, sand in water mixture Mixtures 12 (2) Homogenous Mixtures: the parts mixed together cannot be distinguished from one another...completely uniform in composition. Give examples of a homogenous Examples: Air, Kool-aid, Brass, salt water, milk mixture Differentiate Types of Homogenous mixtures between a homogenous 1. Suspensions mixture and a i.e. chocolate milk, muddy water, Italian dressing heterogeneous mixture. They are cloudy (usually a liquid mixed with small solid particles) Identify an example of a suspension. Needs to be shaken or stirred to keep the solids from Will the solid settling particles settle in a suspension? The solids can be filtered out 2.
    [Show full text]
  • Classification of Matter Section ●1 Composition of Matter
    266_277_Ch15_RE_896315.qxd 3/23/10 3:04 AM Page 266 S-034 113:GO00492:GPS_Reading_Essentials_SE%0:XXXXXXXXXXXXX_SE:Application_Files_ chapter 15 Classification of Matter section ●1 Composition of Matter What You’ll Learn Before You Read ■ what substances and mixtures are Matter is all around you. You breathe matter, sit on it, and ■ how to identify drink it every day. What words would you use to describe elements and different kinds of matter? compounds ■ the difference between solutions, colloids, and suspensions Read to Learn Underline Look for different descriptions of matter Pure Substances as you read each paragraph. Underline these descriptions. Have you ever seen a print that looked like a real painting? Read the underlined descriptions Did you have to touch it to find out? The smooth or rough again after you’ve finished surface told you whether it was a painting or a print. Each reading the section. material has its own properties. The properties of materials can be used to classify them into categories. Each material is made of a pure substance or of a mix of substances. A substance is a type of matter that is always made of the same material or materials. A substance can be either an element or a compound. Some substances you might recognize are helium, aluminum, water, and salt. What are elements? All substances are made of atoms. A substance is an element if all the atoms in the substance are the same. The graphite in your pencil is an element. The copper coating on most pennies is an element, too.
    [Show full text]
  • Alexandre Édouard Baudrimont: Crystallography, Colloids, Aqua Regia
    Revista CENIC. Ciencias Químicas ISSN: 1015-8553 ISSN: 2221-2442 [email protected] Centro Nacional de Investigaciones Científicas Cuba Alexandre Édouard Baudrimont: Crystallography, colloids, aqua regia Wisniak, Jaime Alexandre Édouard Baudrimont: Crystallography, colloids, aqua regia Revista CENIC. Ciencias Químicas, vol. 49, no. 1, 2018 Centro Nacional de Investigaciones Científicas, Cuba Available in: https://www.redalyc.org/articulo.oa?id=181661081002 PDF generated from XML JATS4R by Redalyc Project academic non-profit, developed under the open access initiative Jaime Wisniak. Alexandre Édouard Baudrimont: Crystallography, colloids, aqua regia Articulos de Revision Alexandre Édouard Baudrimont: Crystallography, colloids, aqua regia Alexandre Édouard Baudrimont: Cristalografía, coloides, agua regia Jaime Wisniak a Redalyc: https://www.redalyc.org/articulo.oa? Ben-Gurion University of the Negev, Israel id=181661081002 [email protected] Received: 03 January 2018 Accepted: 15 February 2018 Abstract: Alexander Édouard Baudrimont (1806-1880) was a French physician and pharmacist that carried on fundamental research on a wide variety of subjects, among them, philosophy of science, linguistic, colloidal chemistry, cosmology, crystallography, mechanics of materials, etc. e same as Ampère, he proposed a new theory where only certain geometrical shapes were able to induce a chemical reaction. When atoms combined to form and integral molecule, they assumed an arrangement that if not regular, was at least symmetric. Chemical formulas did not represent the absolute number of atoms present; they represented only a number proportional to the real one. Crystalline particles were always small polyhedrons, which adapted one to the other without leaving empty spaces, a condition satisfied only by only cuboids, hexahedral prisms, and dodecahedrons.
    [Show full text]
  • Colloidal Systems with a Short-Range Attraction and Long-Range Repulsion: Phase Diagrams, Structures, and Dynamics Yun Liu1,2,3 and Yuyin Xi1,2
    Available online at www.sciencedirect.com Current Opinion in ScienceDirect Colloid & Interface Science Colloidal systems with a short-range attraction and long-range repulsion: Phase diagrams, structures, and dynamics Yun Liu1,2,3 and Yuyin Xi1,2 Abstract Colloidal systems with both a short-range attraction and long- Keywords Colloids, Short-range attraction, Long-range repulsion, Phase diagram. range repulsion (SALR) have rich phases compared with the traditional hard sphere systems or sticky hard sphere systems. The competition between the short-range attraction and long- Introduction range repulsion results in the frustrated phase separation, Colloids are commonly encountered in many materials which leads to the formation of intermediate range order (IRO) of our daily life. They can exist in a wide range of shapes structures and introduces new phases to both equilibrium and and compositions, such as micelles, quantum dots, nonequilibrium phase diagrams, such as clustered fluid, clus- proteins, star polymers, synthetic nanoparticles, and ter percolated fluid, Wigner glass, and cluster glass. One active colloids. Studying the structure and dynamics of hallmark feature of many SALR systems is the appearance of colloidal systems is essential to understand, control, and the IRO peak in the interparticle structure factor, which is predict the macroscopic properties of these materials associated with different types of IRO structures. The rela- [1e4]. Model colloidal systems have been serving as tionship between the IRO peak and the clustered fluid state important testbeds to prove theories and demonstrate has been careful investigated. Not surprisingly, the morphology the underlining physics mechanisms of many interesting of clusters in solutions can be affected and controlled by the phenomena in complicated systems [3,5e7].
    [Show full text]
  • Colloid Chemistry
    gels Editorial Colloid Chemistry Clemens K. Weiss Department of Life Sciences and Engineering, University of Applied Sciences Bingen, Berlinstrasse 109, 55411 Bingen, Germany; [email protected]; Tel.: +49-6721-409270 Received: 12 July 2018; Accepted: 17 July 2018; Published: 23 July 2018 Colloid Chemistry has always been an integral part of several chemical disciplines. Ranging from preparative inorganic chemistry to physical chemistry, researchers have always been fascinated in the dimensions and the possibilities colloids offer. Since the advent of nanotechnology and analytical tools, which have evolved across recent decades, colloid chemistry or “nano-chemistry” has become essential for high-level research in various disciplines. The contributions to this Special Issue cover most of the important aspects: choice, design and synthesis of building blocks; preparation and modification of gel and colloidal structures; analysis and application as well as the study of physical and physicochemical phenomena. Most importantly, the contributions connect these aspects, relate them and present a comprehensive overview. Small molecules can act as gelators as well as polymers or colloids. The chemical structure of these building blocks defines the interactions between them and thus the structure and properties of the macroscopic material. Malo de Molina et al. [1] present a comprehensive review of colloidal structures generated by self-assembly of amphiphilic molecules. Assemblies of small molecule surfactants as well as amphiphilic polymers in water can form hydrogels. The resulting morphologies are discussed and routes to gelation are described. Latxague et al. [2] show a synthetic approach towards a bolaamphiphile based on structures found in living nature. Based on thymidine and a saccharide moiety two hydrophilic groups are linked symmetrically to a hydrophobic spacer via click chemistry.
    [Show full text]
  • Soft Condensed Matter Daan Frenkel
    Physica A 313 (2002) 1–31 www.elsevier.com/locate/physa Soft condensed matter Daan Frenkel FOM Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJAmsterdam, The Netherlands Abstract These lectures illustrate some of the concepts of soft-condensed matter physics, taking exam- ples from colloid physics. Many of the theoretical concepts will be illustrated with the results of computer simulations. After a brief introduction describing interactions between colloids, the paper focuses on colloidal phase behavior (in particular, entropic phase transitions), colloidal hydrodynamics and colloidal nucleation. c 2002 Elsevier Science B.V. All rights reserved. PACS: 82.70.Dd; 02.70.Ns; 64.70.Md; 64.60.Qb Keywords: Soft matter; Colloids; Computer simulation 1. Introduction The topic of these lectures is soft condensed matter physics—but not all of it. My aim is to discuss a few examples that illustrate the analogies and di6erences between “soft” and “hard” matter. The choice of the examples is biased by my own experience. Most of the examples that I discuss apply to colloids. In many ways, colloids behave like giant atoms, and quite a bit of the colloid physics can be understood in this way. However, much of the interesting behavior of colloids is related to the fact that they are, in many respects, not like atoms. In this lecture, I shall start from the picture of colloids as oversized atoms or molecules, and then I shall selectively discuss some features of colloids that are di6erent. My presentation of the subject will be a bit strange, because I am a computer simulator, rather than a colloid scientist.
    [Show full text]