R‐RAFT approach for the polymerization of N‐isopropylacrylamide with a star poly(ε‐caprolactone) core

Reversible addition‐fragmentation chain transfer (RAFT) polymerization is a more robust and versatile approach than other living free radical polymerization methods, providing a reactive thiocarbonylthio end group. A series of well‐defined star diblock [poly(ε‐caprolactone)‐b‐poly(N‐isopropylacrylamide)]₄ (SPCLNIP) copolymers were synthesized by R‐RAFT polymerization of N‐isopropylacrylamide (NIPAAm) using [PCL‐DDAT]₄ (SPCL‐DDAT) as a star macro‐RAFT agent (DDAT: S‐1‐dodecyl‐S′‐(α, α′‐dimethyl‐α″‐acetic acid) trithiocarbonate). The R‐RAFT polymerization showed a controlled/“living” character, proceeding with pseudo‐first‐order kinetics. All these star polymers with different molecular weights exhibited narrow molecular weight distributions of less than 1.2. The effect of polymerization temperature and molecular weight of the star macro‐RAFT agent on the polymerization kinetics of NIPAAm monomers was also addressed. Hardly any radical–radical coupling by‐products were detected, while linear side products were kept to a minimum by careful control over polymerization conditions. The trithiocarbonate groups were transferred to polymer chain ends by R‐RAFT polymerization, providing potential possibility of further modification by thiocarbonylthio chemistry. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Biotin functionalized poly(sulfonic acid)s for bioconjugation: In situ binding monitoring by QCM‐D

We describe the synthesis of biotin end functionalized poly(sulfonic acid)s via living radical polymerization (LRP) for conjugation to Avidin. Quartz crystal microbalance (QCM‐D) and competitive binding studies were used to confirm this conjugation. A biotin initiator for copper‐mediated LRP was used to provide acrylamide and methacrylate based polymers with the functional end group. This investigation revealed that 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid was not a suitable monomer in its acid form but was successfully used in its sodium salt form. A second monomer, 3‐sulfopropylmethacrylate as the potassium salt was also studied and both monomers produced polymers with polydispersities <1.3 and 1.4, respectively. Evolution of molecular weight with respect to time indicated that the polymerization of the acrylamide polymer is controlled. Quartz crystal microbalance with dissipation monitoring was used to confirm that the biotinylated polymers were able to bind to Avidin in situ. The gold surface of a quartz crystal was chemically modified resulting in a stable monolayer of Avidin; the biotinylated polymers were passed over the functionalized surface and their grafting ability was examined. A competitive binding evaluation was undertaken with 2‐(4‐hydroxyphenylazo)benzoic acid (HABA) dye to provide visual verification of conjugation. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Anionic polymerization of N,N‐dialkyl‐2‐methylenebut‐3‐enamide: Effect of alkyl substituents on polymerization behavior

Anionic polymerizations of three 1,3‐butadiene derivatives containing different N,N‐dialkyl amide functions, N,N‐diisopropylamide (DiPA), piperidineamide (PiA), and cis‐2,6‐dimethylpiperidineamide (DMPA) were performed under various conditions, and their polymerization behavior was compared with that of N,N‐diethylamide analogue (DEA), which was previously reported. When polymerization of DiPA was performed at ?78 °C with potassium counter ion, only trace amounts of oligomers were formed, whereas polymers with a narrow molecular weight distribution were obtained in moderate yield when DiPA was polymerized at 0 °C in the presence of LiCl. Decrease in molecular weight and broadening of molecular weight distribution were observed when polymerization was performed at a higher temperature of 20 °C, presumably because of the effect of ceiling temperature. In the case of DMPA, no polymer was formed at 0 °C and polymers with relatively broad molecular weight distributions (M_w/M_n = 1.2) were obtained at 20 °C. The polymerization rate of PiA was much faster than that of the other monomers, and poly(PiA) was obtained in high yield even at ?78 °C in 24 h. The microstructure of the resulting polymers were exclusively 1,4‐ for poly(DMPA), whereas 20–30% of the 1,2‐structure was contained in poly(DiPA) and poly(PiA). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3714–3721, 2010     

A strategy for synthesis of ion‐bonded amphiphilic miktoarm star copolymers via supramolecular macro‐RAFT agent

Amphiphilic supramolecular miktoarm star copolymers linked by ionic bonds with controlled molecular weight and low polydispersity have been successfully synthesized via reversible addition‐fragmentation chain transfer (RAFT) polymerization using an ion‐bonded macromolecular RAFT agent (macro‐RAFT agent). Firstly, a new tetrafunctional initiator, dimethyl 4,6‐bis(bromomethyl)‐isophthalate, was synthesized and used as an initiator for atom transfer radical polymerization (ATRP) of styrene to form polystyrene (PSt) containing two ester groups at the middle of polymer chain. Then, the ester groups were converted into tertiary amino groups and the ion‐bonded supramolecular macro‐RAFT agent was obtained through the interaction between the tertiary amino group and 2‐dodecylsulfanylthiocarbonylsulfanyl‐2‐methyl propionic acid (DMP). Finally, ion‐bonded amphiphilic miktoarm star copolymer, (PSt)₂‐poly(N‐isopropyl‐acrylamide)₂, was prepared by RAFT polymerization of N‐isopropylacrylamide (NIPAM) in the presence of the supramolecular macro‐RAFT agent. The polymerization kinetics was investigated and the molecular weight and the architecture of the resulting star polymers were characterized by means of ¹H‐NMR, FTIR, and GPC techniques. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5805–5815, 2008     

Synthesis of well‐defined macromonomers and comb copolymers from polymers made by atom transfer radical polymerization

Poly(n‐butyl acrylate) macromonomers with predetermined molecular weights (1300 < number‐average molecular weight < 23,000) and low polydispersity indices (<1.2) were synthesized from bromine‐terminated atom transfer radical polymerization polymers via end‐group substitution with acrylic acid and methacrylic acid. These macromonomers, having a high degree of end‐group functionalization (>90%), were radically homopolymerized to obtain comb polymers. A high macromonomer concentration, combined with a low radical flux, was needed to obtain a high conversion of the macromonomers and a reasonable degree of polymerization. By the traditional radical copolymerization of the hydrophobic macromonomers with the hydrophilic monomer N,N‐dimethylaminoethyl methacrylate (DMAEMA), amphiphilic comb copolymers were obtained. The conversions of the macromonomers and comonomer were almost quantitative under optimized reaction conditions. The molecular weights were high (number‐average molecular weight ≈70,000), and the molecular weight distribution was broad (polydispersity index ≈ 3.5). Kinetic measurements showed simultaneous decreases in the macromonomer and DMAEMA concentrations, indicating a relatively homogeneous composition of the comb copolymers over the whole molecular weight range. This was supported by preparative size exclusion chromatography. The copolymerization of poly(n‐butyl acrylate) macromonomers with other hydrophilic monomers such as acrylic acid or N,N‐dimethylacrylamide gave comb copolymers with multimodal molecular weight distributions in size exclusion chromatography and extremely high apparent molecular weights. Dynamic light scattering showed a heterogeneous composition consisting of small (6–9 nm) and large (23–143 nm) particles, probably micelles or other type of aggregates. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3425–3439, 2003     

Synthesis of comb‐like polystyrene with poly(N‐phenyl maleimide‐alt‐p‐chloromethyl styrene) as macroinitiator

The copolymerization of N‐phenyl maleimide and p‐chloromethyl styrene via reversible addition–fragmentation chain transfer (RAFT) process with AIBN as initiator and 2‐(ethoxycarbonyl)prop‐2‐yl dithiobenzoate as RAFT agent produced copolymers with alternating structure, controlled molecular weights, and narrow molecular weight distributions. Using poly(N‐phenyl maleimide‐alt‐p‐chloromethyl styrene) as the macroinitiator for atom transfer radical polymerization of styrene in the presence of CuCl/2,2′‐bipyridine, well‐defined comb‐like polymers with one graft chain for every two monomer units of backbone polymer were obtained. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2069–2075, 2006     

Simultaneous control of the stereospecificity and molecular weight in the ruthenium‐catalyzed living radical polymerization of methyl and 2‐hydroxyethyl methacrylates and sequential synthesis of stereoblock polymers

The stereospecific living radical polymerizations of methyl methacrylate (MMA) and 2‐hydroxyethyl methacrylate (HEMA) were achieved with a combination of ruthenium‐catalyzed living radical and solvent‐mediated stereospecific radical polymerizations. Among a series of ruthenium complexes [RuCl₂(PPh₃)₃, Ru(Ind)Cl(PPh₃)₂, and RuCp*Cl(PPh₃)₂], Cp*–ruthenium afforded poly(methyl methacrylate) with highly controlled molecular weights [weight‐average molecular weight/number‐average molecular weight (M_w/M_n) = 1.08] and high syndiotacticity (r = 88%) in a fluoroalcohol such as (CF₃)₂C(Ph)OH at 0 °C. On the other hand, a hydroxy‐functionalized monomer, HEMA, was polymerized with RuCp*Cl(PPh₃)₂ in N,N‐dimethylformamide and N,N‐dimethylacetamide (DMA) to give syndiotactic polymers (r = 87–88%) with controlled molecular weights (M_w/M_n = 1.12–1.16). This was the first example of the syndiospecific living radical polymerization of HEMA. A fluoroalcohol [(CF₃)₂C(Ph)OH], which induced the syndiospecific radical polymerization of MMA, reduced the syndiospecificity in the HEMA polymerization to result in more or less atactic polymers (mm/mr/rr = 7.2/40.9/51.9%) with controlled molecular weights in the presence of RuCp*Cl(PPh₃)₂ at 80 °C. A successive living radical polymerization of HEMA in two solvents, first DMA followed by (CF₃)₂C(Ph)OH, resulted in stereoblock poly(2‐hydroxyethyl methacrylate) with syndiotactic–atactic segments. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3609–3615, 2006     

Synthesis of poly(arylene thioether)s from protected dithiols and aromatic difluorides with an organic base

Aromatic poly(arylene thioether)s were synthesized from N‐propyl‐S‐carbamate‐protected aromatic dithiols and aromatic difluorides. The deprotection of the protected dithiols with an organic base such as 1,8‐diazabicyclo[5.4.0]‐7‐undecene at room temperature and subsequent polymerization with the difluoride monomers at 120 °C in N‐methyl‐2‐pyrrolidinone produced high molecular weight polymers with intrinsic viscosities as high as 0.45 dL/g. The use of organic bases instead of inorganic bases for the generation of thiophenoxide nucleophile was a convenient way of avoiding metallic impurities in the synthesis of the poly(arylene thioether)s through a nucleophilic aromatic substitution reaction. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2021–2027, 2005     

In situ polymerization and morphology of polypyrrole obtained in water‐soluble polymer templates

Several water‐soluble polymers were used as templates for the in situ polymerization of pyrrole to determine their effect on the generation of nanosized polypyrrole (PPy) particles. The polymers used include: polyvinyl alcohol (PVA), polyethylene oxide (PEO), poly(vinyl butyral), polystyrene sulfonic acid, poly(ethylene‐alt‐maleic anhydride) (PEMA), poly(octadecene‐alt‐maleic anhydride), poly(N‐vinyl pyrrolidone), poly(vinyl butyral‐co‐vinyl alcohol‐co‐vinyl acetate), poly(N‐isopropyl acrylamide), poly(ethylene oxide‐block‐propylene oxide), hydroxypropyl methyl cellulose, and guar gum. The oxidative polymerization of pyrrole was carried out with FeCl₃ as an oxidant. The morphology of PPy particles obtained after drying the resulting aqueous dispersions was examined by optical microscopy, and selected samples were further analyzed via atomic force microscopy. Among the template polymers, PVA was the most efficient in generating stable dispersions of PPy nanospheres in water, followed by PEO and PEMA. The average size of PPy nanospheres was in the range of 160 nm and found to depend on the molecular weight and concentration of PVA. Model reactions and kinetics of the polymerization reaction of pyrrole in PVA were carried out by hydrogen ¹H NMR spectroscopy using ammonium persulfate as an oxidant. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

A versatile single‐electron‐transfer mediated living radical polymerization route to galactoglucomannan graft‐copolymers with tunable hydrophilicity

Cu(0) mediated living radical polymerization was successfully applied to synthesize graft‐copolymers from the hemicellulose acetylated galactoglucomannan. Functionalizing the polysaccharide backbone with α‐bromo isobutyric acid gave rise to a macroinitiator for single‐electron‐transfer mediated living radical polymerization (SET‐LRP). This macroinitiator with a degree of substitution of 0.15 or 0.20 was used in the graft‐SET‐LRP of methyl methacrylate in dimethyl sulfoxide as well as N‐isopropyl acrylamide and acrylamide in water. Kinetic analyses confirm conversions of up to 73% and a controlled behavior of the SET‐LRP process providing high molecular weight hemicellulose‐based hybrid copolymers with a brush‐like architecture. Derived graft‐copolymers varied significantly in solubility properties, ranging from hydrophobic via temperature responsive water‐solubility to water‐soluble. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

RAFT polymerization of alternating styrene‐pentafluorostyrene copolymers

Reversible addition‐fragmentation chain‐transfer (RAFT) polymerization was used to control the alternating copolymerization of styrene and 2,3,4,5,6‐pentaflurostyrene. The RAFT polymerization yields a high degree of control over the molecular weight of the polymers and does not significantly influence the reactivity ratios of the monomers. The controlled free‐radical polymerization could be initiated using AIBN at elevated temperatures or using a redox couple (benzoyl peroxide/N,N‐dimethylaniline) at room temperature, while maintaining control over molecular weight and dispersity. The influence of temperature and solvent on the molecular weight distribution and reactivity ratios were investigated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1555–1559     

Macromolecular brushes synthesized by “grafting from” approach based on “click chemistry” and RAFT polymerization

Well‐defined macromolecular brushes with poly(N‐isopropyl acrylamide) (PNIPAM) side chains on random copolymer backbones were synthesized by “grafting from” approach based on click chemistry and reversible addition‐fragmentation chain transfer (RAFT) polymerization. To prepare macromolecular brushes, two linear random copolymers of 2‐(trimethylsilyloxy)ethyl methacrylate (HEMA‐TMS) and methyl methacrylate (MMA) (poly(MMA‐co‐HEMA‐TMS)) were synthesized by atom transfer radical polymerization and were subsequently derivated to azide‐containing polymers. Novel alkyne‐terminated RAFT chain transfer agent (CTA) was grafted to polymer backbones by copper‐catalyzed 1,3‐dipolar cycloaddition (azide‐alkyne click chemistry), and macro‐RAFT CTAs were obtained. PNIPAM side chains were prepared by RAFT polymerization. The macromolecular brushes have well‐defined structures, controlled molecular weights, and molecular weight distributions (M_w/M_n ≦ 1.23). The RAFT polymerization of NIPAM exhibited pseudo‐first‐order kinetics and a linear molecular weight dependence on monomer conversion, and no detectable termination was observed in the polymerization. The macromolecular brushes can self‐assemble into micelles in aqueous solution. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 443–453, 2010     

Anionic polymerization of N,N‐dialkylacrylamides containing alkoxysilyl groups in the presence of Lewis acids

With Ph₂CHK as an initiator, the anionic polymerization of N‐propyl‐N‐(3‐triisopropoxysilylpropyl)acrylamide ( 4 ) and N‐propyl‐N‐(3‐triethoxysilylpropyl)acryl‐amide generated polymers with predicted molecular weights and narrow molecular weight distributions (MWDs) in the presence of Et₂Zn or Et₃B; however, the resulting polymers obtained in the absence of such Lewis acids had very broad MWDs. The results were ascribed to the coordination of the propagating anionic end to a relatively weak Lewis acid, in which the activity of the end anion was appropriately controlled for moderate polymerization without side reactions. A well‐defined diblock copolymer of 4 and N,N‐diethylacrylamide was also prepared with the binary initiating system of Ph₂CHK and Et₂Zn, whereas no such block copolymer was prepared by polymerization initiated with 1,1‐diphenyl‐3‐methylpentyllithium, as the propagating anion together with the lithium ion reacted with alkoxysilyl side groups on the poly( 4 ) backbone to produce grafted polymers with high molecular weights. The hydrolysis of the alkoxysilyl side groups of poly( 4 ) in acidic water yielded an insoluble gel. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2754‐2764, 2005     

Synthesis of thermo‐responsive poly(N‐vinylcaprolactam)‐containing block copolymers by cobalt‐mediated radical polymerization

Thermo‐responsive block copolymers based on poly(N‐vinylcaprolactam) (PNVCL) have been prepared by cobalt‐mediated radical polymerization (CMRP) for the first time. The homopolymerization of NVCL was controlled by bis(acetylacetonato)cobalt(II) and a molecular weight as high as 46,000 g/mol could be reached with a low polydispersity. The polymerization of NVCL was also initiated from a poly(vinyl acetate)‐Co(acac)₂ (PVAc‐Co(acac)₂) macroinitiator to yield well‐defined PVAc‐b‐PNVCL block copolymers with a low polydispersity (M_w/M_n = 1.1) up to high molecular weights (M_n = 87,000 g/mol), which constitutes a significant improvement over other techniques. The amphiphilic PVAc‐b‐PNVCL copolymers were hydrolyzed into unprecedented double hydrophilic poly(vinyl alcohol)‐b‐PNVCL (PVOH‐b‐PNVCL) copolymers and their temperature‐dependent solution behavior was studied by turbidimetry and dynamic light scattering. Finally, the so‐called cobalt‐mediated radical coupling (CMRC) reaction was implemented to PVAc‐b‐PNVCL‐Co(acac)₂ precursors to yield novel PVAc‐b‐PNVCL‐b‐PVAc symmetrical triblock copolymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Dual responsive poly(N‐isopropylacrylamide) hydrogels having spironaphthoxazines as pendant groups

Stimuli responsive hydrogels (PNIPAAm‐MSp) with a thermoresponsive backbone and photochromic pendant groups were synthesized via free radical polymerization using N‐isopropylacrylamide, modified spironaphthoxazines with a polymerizable double bond (MSp) as photochromic monomer, the crosslinker N,N′‐methylenebis(acrylamide) and the initiator 2,2′‐azobis(isobutyronitrile) in dimethylsulfoxide. The polymers are dual responsive, in that poly(N‐isopropylacrylamide) (PNIPAAm) responds to temperature changes whereas the pendant spironaphthoxazines respond to light. Irradiation enhanced the water absorption of the polymers while increases in temperature decreased it. The irradiated PNIPAAm‐MSp showed best water absorption at 0 °C (Q = 3.25) while water desorbed at higher temperatures (35 °C; Q = 0.30); where Q is the amount of water absorbed by a gram of dry polymer. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3318–3325, 2009     

RAFT‐mediated batch emulsion polymerization of styrene using poly[N‐(4‐vinylbenzyl)‐N,N‐dibutylamine hydrochloride] trithiocarbonate as both surfactant and macro‐RAFT agent

Poly[N‐(4‐vinylbenzyl)‐N,N‐dibutylamine hydrochloride] trithiocarbonate, which contains the reactive trithiocarbonate group and the appending surface‐active groups, is used as both surfactant and macromolecular reversible addition‐fragmentation chain transfer (macro‐RAFT) agent in batch emulsion polymerization of styrene. Under the conditions at high monomer content of ～20 wt % and with the molecular weight of the macro‐RAFT agent ranging from 4.0 to 15.0 kg/mol, well‐controlled batch emulsion RAFT polymerization initiated by the hydrophilic 2‐2′‐azobis(2‐methylpropionamidine) dihydrochloride is achieved. The polymerization leads to formation of nano‐sized colloids of the poly[N‐(4‐vinylbenzyl)‐N,N‐dibutylamine hydrochloride]‐b‐ polystyrene‐b‐poly[N‐(4‐vinylbenzyl)‐N,N‐dibutylamine hydrochloride] triblock copolymer. The colloids generally have core‐shell structure, in which the hydrophilic block forms the shell and the hydrophobic block forms the core. The molecular weight of the triblock copolymer linearly increases with increase in the monomer conversion, and the values are well‐consistent with the theoretical ones. The molecular weight polydispersity index of the triblock copolymer is below 1.2 at most cases of polymerization. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis of a new 2‐amino‐glycan,poly‐(1→6)‐α‐D‐mannosamine,by ring‐opening polymerization of 1,6‐anhydro‐mannosamine derivatives

A stereoregular 2‐amino‐glycan composed of a mannosamine residue was prepared by ring‐opening polymerization of anhydro sugars. Two different monomers, 1,6‐anhydro‐2‐azido‐mannose derivative ( 3 ) and 1,6‐anhydro‐2‐(N, N‐dibenzylamino)‐mannose derivative ( 6 ), were synthesized and polymerized. Although 3 gave merely oligomers, 6 was promptly polymerized into high polymers of the number‐average molecular weight (M_n) of 2.3 × 10⁴ to 2.9 × 10⁴ with 1,6‐α stereoregularity. The differences of polymerizability of 3 and 6 from those of the corresponding glucose homologs were discussed. It was found that an N‐benzyl group is exceedingly suitable for protecting an amino group in the polymerization of anhydro sugars of a mannosamine type. The simultaneous removal of O‐ and N‐benzyl groups of the resulting polymers was achieved by using sodium in liquid ammonia to produce the first 2‐amino‐glycan, poly‐(1→6)‐α‐D ‐mannosamine, having high molecular weight through ring‐opening polymerization of anhydro sugars.© 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and characterization of multifunctional polymers via atom transfer radical polymerization of N‐(ω′‐alkylcarbazolyl) methacrylates initiated by Ru(II) polypyridyl chromophores

A series of poly(N‐(ω′‐alkylcarbazoly) methacrylates) tris(bipyridine) Ru‐centered bifunctional polymers with good filming, thermal, and solubility properties were synthesized and characterized. Atom transfer radical polymerization (ATRP) of N‐(ω′‐alkylcarbazoly) methacrylates in solution was used, where Ru complexes with one and three initiating sites acted as metalloinitiators with NiBr₂(PPh₃)₂ as a catalyst. ATRP reaction conditions with respect to polymer molecular weights and polydispersity indices (PDI) of the target bifunctional polymers were examined. Electronic absorption and emission spectra of the resultant functional polymers provided evidence of chromophore presence within a single polymeric chain. The thermal properties of all polymers were also investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), and these analyses have indicated that these polymers possess higher thermal stabilities than poly(methyl methacrylate) (PMMA) obtained via free radical polymerization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6057–6072, 2005     

Precision synthesis of sustainable thermoplastic elastomers from lysine‐derived monomers

Novel renewable thermoplastic elastomers were synthesized by sequential polymerization of lysine‐ and itaconic acid‐derived monomers. Ring‐opening polymerization of lysine‐based O‐carboxyanhydride monomer using diethylene glycol as an initiator gave well‐defined α,ω‐dihydroxy functionalized lysine‐derived polyesters. The M _n of these polyesters increased with the monomer conversion while retaining relatively narrow molecular weight distributions. Based on the successful controlled polymerization and esterification of α,ω‐dihydroxy with 2‐bromoisobutyryl bromide, the resultant Br‐PL‐Br macroinitiator was used for the atom transfer radical polymerization of N‐phenylitaconimide (PhII). Three poly(N‐phenylitaconimide)‐b‐polyester‐b‐poly(N‐phenylitaconimide) triblock copolymers were prepared containing 12 ? 25 mol% PPhII, as determined by ¹H NMR spectroscopy. The properties of the obtained triblock copolymer are evaluated as high‐performance and renewable thermoplastic elastomer materials. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 349–355     

Novel thermoresponsive fluorinated double‐hydrophilic poly{[N‐(2,2‐difluoroethyl)acrylamide]‐b‐[N‐(2‐fluoroethyl)acrylamide]} block copolymers

Novel thermoresponsive double‐hydrophilic fluorinated block copolymers were successfully synthesized by reversible addition‐fragmentation chain transfer (RAFT) polymerization. Poly[N‐(2,2‐difluoroethyl)acrylamide] (P2F) was synthesized via RAFT polymerization of N‐(2,2‐difluoroethyl)acrylamide (M2F) using 2‐dodecylsulfanylthiocarbonylsulfanyl‐2‐methylpropionic acid (DMP) as the chain transfer agent (CTA) and 2,2′‐azobisisobutyronitrile (AIBN) as the initiator. The resulting P2F macroCTA was further chain extended with N‐(2‐fluoroethyl)acrylamide (M1F) to yield poly{[N‐(2,2‐difluoroethyl)acrylamide]‐b‐[N‐(2‐fluoroethyl)acrylamide]} (P2F‐b‐P1F) block copolymers with different lengths of the P1F block. Molecular weight and molecular weight distribution were determined by gel permeation chromatography. The average molecular weight (M_n) of the resulting polymers ranged from 2.9 × 10⁴ to 5.8 × 10⁴ depending on the length of the P1F block. The molecular weight distribution was low (M_w/M_n = 1.11–1.19). Turbidimetry by UV‐Visble (UV‐Vis) spectroscopy, dynamic light scattering, and in situ temperature‐dependent ¹H NMR measurements demonstrated that the P2F block underwent a thermal transition from hydrophilic to hydrophobic, which in turn induced self‐assembly from unimers to aggregates. Transmission electron microscopy studies demonstrated that polymeric aggregates formed from an aqueous solution of P2F‐b‐P1F at 60 °C were disrupted by cooling down to 20 °C and regenerated by heating to 60 °C. Temperature‐triggered release of a model hydrophobic drug, coumarin 102, was also demonstrated. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013