Controlled/Living Radical Polymerization in Aqueous Media: Homogeneous and Heterogeneous Systems
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Prog. Polym. Sci. 26 =2001) 2083±2134 www.elsevier.com/locate/ppolysci Controlled/living radical polymerization in aqueous media: homogeneous and heterogeneous systems Jian Qiua, Bernadette Charleuxb,*, KrzysztofMatyjaszewski a aDepartment of Chemistry, Center for Macromolecular Engineering, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA bLaboratoire de Chimie MacromoleÂculaire, Unite Mixte associeÂe au CNRS, UMR 7610, Universite Pierre et Marie Curie, Tour 44, 1er eÂtage, 4, Place Jussieu, 75252 Paris cedex 05, France Received 27 July 2001; accepted 30 August 2001 Abstract Controlled/living radical polymerizations carried out in the presence ofwater have been examined. These aqueous systems include both the homogeneous solutions and the various heterogeneous media, namely disper- sion, suspension, emulsion and miniemulsion. Among them, the most common methods allowing control ofthe radical polymerization, such as nitroxide-mediated polymerization, atom transfer radical polymerization and reversible transfer, are presented in detail. q 2001 Elsevier Science Ltd. All rights reserved. Keywords: Aqueous solution; Suspension; Emulsion; Miniemulsion; Nitroxide; Atom transfer radical polymerization; Reversible transfer; Reversible addition-fragmentation transfer Contents 1. Introduction ..................................................................2084 2. General aspects ofconventional radical polymerization in aqueous media .....................2089 2.1. Homogeneous polymerization .................................................2089 2.2. Heterogeneous polymerizations ................................................2089 2.2.1. Suspension polymerization .............................................2090 2.2.2. Emulsion polymerization ..............................................2091 2.2.3. Miniemulsion polymerization ...........................................2094 3. Controlled/living free-radical polymerization methods . .................................2096 3.1. General features and experimental criteria for controlled/living polymerization .............2096 3.1.1. Feature 1: internal ®rst-order kinetics with respect to monomer ...................2096 3.1.2. Feature 2: linear growth ofdegree ofpolymerization =DP n) with conversion .........2096 3.1.3. Feature 3: narrow molar mass distribution . .................................2097 * Corresponding author. Tel./fax: 133-1-44-27-70-89. E-mail addresses: [email protected] =B. Charleux), [email protected] =K. Matyjaszewski). 0079-6700/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved. PII: S0079-6700=01)00033-8 2084 J. Qiu et al. / Prog. Polym. Sci. 26 52001) 2083±2134 3.1.4. Feature 4: long-lived polymer chains ......................................2097 3.2. Stable free radical polymerization =SFRP) ........................................2098 3.3. Atom transfer radical polymerization =ATRP) .....................................2099 3.4. Reversible/degenerative transfer reaction .........................................2100 4. Controlled/living radical polymerization in aqueous solution ...............................2101 5. Controlled/living radical polymerization in aqueous dispersed systems ........................2104 5.1. Nitroxide mediated polymerization =NMP) ........................................2105 5.1.1. Precipitation and dispersion polymerizations .................................2105 5.1.2. Suspension polymerization . ............................................2105 5.1.3. Emulsion polymerization . ............................................2108 5.1.4. Miniemulsion polymerization ............................................2110 5.2. Atom transfer radical polymerization =ATRP) .....................................2112 5.2.1. Direct ATRP ........................................................2113 5.2.2. Reverse ATRP ......................................................2118 5.3. Reversible transfer radical polymerization ........................................2119 5.3.1. Degenerative iodine transfer ............................................2119 5.3.2. Reversible addition-fragmentation transfer ..................................2120 5.4. Peculiarities ofkinetics in controlled/living emulsion and miniemulsion polymerizations . .2126 5.4.1. Nucleation step ......................................................2126 5.4.2. Kinetics ...........................................................2127 6. Conclusions ..................................................................2129 Acknowledgements ................................................................2130 References ......................................................................2130 1. Introduction Since Staudinger [1] proposed the concept ofa chain polymerization and the basic structure ofa polymer molecule eight decades ago, polymer science and technology has experienced an immense development that has revolutionized the look ofthe world and the lifeofhuman beings. Numerous polymeric materials have been created thanks to continuous progress in understanding the fundamentals ofpolymerization. One ofthe greatest contributions to this ®eld fromsynthetic polymer chemists is the development ofliving polymerization methodology, which allows the preparation ofmacromolecules with the maximum degree ofstructural and compositional homogeneity. As a consequence, well-de®ned polymers with precise molar masses, compositions, topologies and functionalities can be tailor-made. This is a signi®cant step toward the ultimate goal ofpolymer synthesis, when the design ofnovel materials is only limited by the imagination ofhuman beings. The terms of`living polymerization' and `living polymers' were introduced by Szwarc [2] in 1956, although prior to his classical work, Ziegler [3] and Flory [4] also described similar concepts. By de®nition, a living polymerization is a chain polymerization that proceeds without the occurrence of irreversible chain breaking processes, i.e. chain transfer and termination. For nearly 30 years after Szwarc reported his insightful work, living polymerization of vinyl monomers had been restricted to anionic polymerization systems. But in 1960s and 1970s, several cationic ring-opening polymerizations ofheterocyclic monomers were foundto proceed with most undesirable side reactions virtually absent [5±7]. It was discovered that ifa dynamic equilibrium between an active and dormant species was formed, it allowed for ®ne tuning of the polymerization of tetrahydrofuran [8,9]. This concept of dynamic equilibrium was eventually extended to vinyl monomers in early 1980s, triggering the J. Qiu et al. / Prog. Polym. Sci. 26 52001) 2083±2134 2085 Nomenclature n~ average number ofradicals per particle [I] initiator concentration [I]0 initial initiator concentration [M] monomer concentration [M]0 initial monomer concentration AA acrylic acid ACPA see V-501 AEROSOL-MA80 sodium dihexyl sulfosuccinate AIBN azobisisobutyronitrile AN acrylonitrile ATRP atom transfer radical polymerization BPMOA N,N-bis=2-pyridylmethyl)octylamine BPMODA N,N-bis=2-pyridylmethyl)octadecylamine BPO benzoyl peroxide Bpy 2,20-bipyridine Brij98 C12H25±=OCH2CH2)20±OH CD cyclodextrine CLP controlled/living polymerization cmc critical micelle concentration CRP controlled/living radical polymerization CSA camphorsulfonic acid CTAB cetyl trimethyl ammonium bromide dAbpy 4,40-dialkyl-2,20-bipyridine, alkyl: mixture ofpentyl and 5-nonyl DCP dicumyl peroxide dHDbpy 4,40-di=9-heptadecyl)-2,20-bipyridine DMAEMA 2-=dimethylamino)ethyl methacrylate dNbpy 4,4-di=5-nonyl)-2,20-bipyridine DOWFAX8390 dihexadecyl disulfonated diphenyloxide disodium salt =Dow Chemical) DPn number average degree ofpolymerization DPw weight average degree ofpolymerization DRI differential refractive index detection dTbpy 4,40-di-t-butyl-2.20-bipyridine EBiB ethyl 2-bromoisobutyrate 2 1 Forafac C8F17CH2CH2COO K =Ato®na) HEA 2-hydroxyethyl acrylate HEMA 2-hydroxyethyl methacrylate HLB hydrophilic-lipophilic balance HV25 nonionic poly=ethylene oxide) DPn 25 nonyl phenol surfactant =Witco) Ip DPw=DPn Mw=Mn polydispersity index K activation/deactivation equilibrium constant =dimension depends on the system) ka rate constant ofactivation =dimension depends on the system) 2086 J. Qiu et al. / Prog. Polym. Sci. 26 52001) 2083±2134 21 21 kd rate constant ofdeactivation =l mol s ) 21 21 kp rate constant ofpropagation =l mol s ) Kraton copolymer ofethylene and butylene 21 21 kt rate constant ofirreversible termination =l mol s ) 21 21 ktr rate constant oftransfer=l mol s ) MALDI-TOF MS matrix-assisted laser desorption/ionisation Ð time-of-¯ight mass spectrometry Me6TREN tris[2-=dimethylamino)ethyl]amine MEMA 2-=N-morpholino)ethyl methacrylate MMA methyl methacrylate MMD molar mass distribution 21 Mn number average molar mass =g mol ) 21 Mw weight average molar mass =g mol ) NA Avogadro's number NaMA sodium methacrylate NaSS sodium styrenesulfonate NaVBA sodium vinylbenzoate n-BA n-butyl acrylate n-BMA n-butyl methacrylate NMP nitroxide-mediated radical polymerization NMR nuclear magnetic resonance OEGMA oligo=ethylene glycol) methacrylate OP-10 polyoxyethylene nonyl phenyl ether P=NaSS) poly=sodium styrenesulfonate) P=n-BA) poly=n-butyl acrylate) P=n-BMA) poly=n-butyl methacrylate) PMDETA N,N,N0,N00,N00-pentamethyldiethylenetriamine PMMA poly=methyl methacrylate) PRE persistent radical effect PS polystyrene PVA poly=vinyl alcohol) PVP poly=N-vinylpyrrolidone) RAFT reversible addition-fragmentation transfer 21