Synthesis and properties of crosslinked chiral nanoparticles via RAFT miniemulsion polymerization

Crosslinked chiral nanoparticles were successfully synthesized via reversible addition‐fragmentation chain transfer (RAFT) miniemulsion polymerization of 6‐O‐p‐vinylbenzyl‐1,2:3,4‐di‐O‐isopropylidene‐D ‐galactopyranose (VBPG) using linear poly(VBPG) as the macro‐RAFT agent. The polymerization of VBPG in the absence of crosslinker was first studied and the kinetic results showed that the molecular weights of the obtained poly(VBPG) increased linearly with the monomer conversion and was in good consistency with the corresponding theoretical ones while there remained a relative narrow polydispersity. The effect of the amount of crosslinker, divinylbenzene, on the nanoparticle size and chiral separation properties of the obtained nanoparticles were investigated in detail using four racemates ±‐3‐Amino‐1,2‐propanediol, D ,L ‐arabinose, D ,L ‐tartaric acid, and D ,L ‐mandelic acid. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1324–1331, 2010     

Preparation,characterization, and chiral recognition of optically active polymers containing pendent chiral units via reversible addition‐fragmentation chain transfer polymerization

Optically active polymers bearing chiral units at the side chain were prepared via reversible addition‐fragmentation chain transfer (RAFT) polymerization in the presence of 2,2′‐azobisisobutyronitrile (AIBN)/benzyl dithiobenzoate (BDB), using a synthesized 6‐O‐p‐vinylbenzyl‐1,2:3,4‐Di‐O‐isopropylidene‐D ‐galactopyranose (VBPG) as the monomer. The experimental results suggested that the polymerization of the monomer proceeded in a living fashion, providing chiral group polymers with narrow molecular weight distributions. The optically active nature of the obtained poly (6‐O‐p‐vinylbenzyl‐1,2:3,4‐Di‐O‐isopropylidene‐D ‐galactopyranose) (PVBPG) was studied by investigating the dependence of specific rotation on the molecular weight of PVBPG and the concentration of PVBPG in tetrahydrofuran (THF). The results showed the specific rotation of PVBPG increased greatly with the decrease of the concentration of the PVBPG homopolymer. In addition, the effect of block copolymers of PVBPG on the optically active nature was also investigated by preparing a series of diblock copolymers of poly(methyl methacrylate) (PMMA)‐b‐PVBPG, polystyrene (PS)‐b‐PVBPG, and poly(methyl acrylate) (PMA)‐b‐PVBPG. It was found that both the homopolymer and the diblock copolymers possessed specific rotations. Finally, the ability of chiral recognition of the PVBPG homopolymer was investigated via an enantiomer‐selective adsorption experiment. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3788–3797, 2007     

Synthesis and micellization of thermoresponsive galactose‐based diblock copolymers

Thermoresponsive double hydrophilic diblock copolymers poly(2‐(2′‐methoxyethoxy)ethyl methacrylate‐co‐oligo(ethylene glycol) methacrylate)‐b‐poly(6‐O‐methacryloyl‐D ‐galactopyranose) (P(MEO₂MA‐co‐OEGMA)‐b‐PMAGP) with various compositions and molecular weights were obtained by deprotection of amphiphilic diblock copolymers P(MEO₂MA‐co‐OEGMA)‐b‐poly(6‐O‐methacryloyl‐1,2:3,4‐di‐O‐isopropylidene‐D ‐galactopyranose) (P(MEO₂MA‐co‐OEGMA)‐b‐PMAlpGP), which were prepared via reversible addition‐fragmentation chain transfer (RAFT) polymerization using P(MEO₂MA‐co‐OEGMA) as macro‐RAFT agent. Dynamic light scattering and UV–vis studies showed that the micelles self‐assembled from P(MEO₂MA‐co‐OEGMA)‐b‐PMAlpGP were thermoresponsive. A hydrophobic dye Nile Red could be encapsulated by block copolymers P(MEO₂MA‐co‐OEGMA)‐b‐PMAGP upon micellization and released upon dissociation of the formed micelles under different temperatures. The galactose functional groups in the PMAGP block have specific interaction with HepG2 cells, and P(MEO₂MA‐co‐OEGMA)‐b‐PMAGP has potential applications in hepatoma‐targeting drug delivery and biodetection. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Well‐defined pH‐sensitive block glycopolymers via reversible addition–fragmentation chain transfer radical polymerization: Synthesis,characterization, and recognition with lectin

pH‐Sensitive block glycopolymers of poly(2‐(diethylamino)ethyl methacrylate) (PDEAEMA) and poly(3‐O‐methacryloy‐α,β‐D ‐glucopyranose) (PMAGlc) were synthesized via reversible addition–fragmentation chain transfer (RAFT) radical polymerization based on protected glycomonomer 3‐O‐methacryloyl‐1,2:5,6‐di‐O‐isopropylidene‐D ‐glucofuranose (MAIpGlc). It was found that RAFT homopolymerization of MAIpGlc proceeded in a controlled fashion with 4‐cyanopentanoic acid dithiobenzoate as chain transfer agent. Using the dithioester‐capped PDEAEMA as macro‐RAFT agent, block copolymerization of MAIpGlc was in good control as indicated by the linear pseudo first‐order kinetic plot, the linear increment of number‐average molecular weights as well as narrow and symmetrical gel permeation chromatography peaks, and low polydispersities. Well‐defined diblock copolymers of DEAEMA and MAIpGlc were prepared successfully through the chain extension of PDEAEMA. The deprotection of MAIpGlc units in trifluoroacetic acid/H₂O solution afforded PDEAEMA‐b‐PMAGlc block glycopolymer. The self‐assembly behavior of PDEAEMA‐b‐PMAGlc in aqueous solution was investigated by using ¹H NMR, UV‐vis spectroscopy, dynamic light scattering, and transmission electron microscopy. The results demonstrated that spherical micelles with PDEAEMA as the hydrophobic cores and PMAGlc as the hydrophilic shells were formed in alkaline aqueous solution. These glucose‐installed micelles had specific recognition with Concanavalin A. The combination of pH‐sensitivity of PDEAEMA and biomolecular recognition of PMAGlc in one micellar system may create a multifunctional platform for targeted delivery, biomimetics, and biodection. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3350–3361, 2010     

“Bottom‐Up” Fabrication of BODIPY‐Functionalized Fluorescent Hyperbranched Glycopolymers for Hepatoma‐Targeted Imaging

A novel type of multivalent and highly specific fluorescent hyperbranched glycopolymers h‐P(GalEA‐co‐VBPT‐co‐BYMA) (hPGVB) is designed and prepared successfully via a facile “bottom‐up” strategy. The acetylated hPGVB is prepared by one‐pot reversible addition‐fragmentation chain transfer (RAFT) copolymerization of acrylate‐type galactose monomers AcGalEA and methacrylate‐type fluorescent monomers BYMA in presence of an inimer‐type RAFT chain transfer agent. After deacetylation, the resulting amphiphilic hPGVB can self‐assemble into stable nanoparticles in aqueous media, showing strong green fluorescence with relative high quantum yields and good photostability. The cell viability study indicates the excellent biocompatibility of the hPGVB fluorescent nanoparticles (FNPs) against HepG2 and NIH3T3 cells. More importantly, comparing with the galactose‐free fluorescent hyperbranched polymers h‐P(OEGMA‐co‐VBPT‐co‐BYMA), hPEVB FNPs can be selectively internalized by asialoglycoprotein (ASGP) receptor‐rich HepG2 cells, indicating their potential application in the bioimaging fields.     

Carbohydrate‐based amphiphilic diblock copolymers: Synthesis,characterization, and aqueous properties

Amphiphilic poly(ε‐caprolactone)‐b‐poly[(methacrylate‐graft‐poly(ethylene oxide))‐co‐6‐O‐methacryloyl‐D ‐galactopyranose] (PCL‐b‐P(MAPEO‐co‐GaMa)) with various compositions and molecular weights were synthesized via a controlled four‐step strategy. The first step involves the synthesis of functionalized poly(ε‐caprolactone) macroinitiator by ring‐opening polymerization (ROP) of ε‐caprolactone (CL) as initiated by aluminum triisopropoxide (Al(OⁱPr)₃). After selective bromination of the hydroxyl end‐group of the resulting α‐isopropoxy, ω‐hydroxy poly(ε‐caprolactone) by using 2‐bromoisobutyryl bromide, the controlled radical copolymerization of α‐methoxy, ω‐methacrylate poly(ethylene oxide) (MAPEO) with 6‐O‐methacryloyl‐1,2;3,4‐di‐O‐isopropylidene‐D ‐galactopyranose (DIGaMa) was performed by atom transfer radical polymerization (ATRP) in THF at 60 °C using CuBr ligated with 1,1,4,7,10,10 hexamethyltriethylenetetramine (HMTETA) as catalytic complex. In the final step, isopropylidene protective functions were selectively removed using an aqueous formic acid solution leading to the expected amphiphilic graft copolymers. The molecular characterization of those copolymers was performed by ¹H NMR spectroscopy and gel permeation chromatography (GPC) analysis. The self‐assembly of the copolymers into micellar aggregates as well as the related critical micellization concentration (CMC) in aqueous media were determined by dynamic light scattering (DLS) and fluorescence spectroscopy, respectively. In parallel, the morphology of the solid deposits of micellar aggregates was examined with atomic force microscopy (AFM). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3662–3672, 2008     

Facile synthesis of star‐shaped copolymers via combination of RAFT and ring opening polymerization

Reversible addition fragmentation chain transfer (RAFT) polymerization and bifunctional sparteine/thiourea organocatalyst‐mediated ring opening polymerization (ROP) were combined to produce poly(L ‐lactide) star polymers and poly(L ‐lactide‐co‐styrene) miktoarm star copolymers architecture following a facile experimental procedure, and without the need for specialist equipment. RAFT was used to copolymerize ethyl acrylate (EA) and hydroxyethyl acrylate (HEA) into poly(EA‐co‐HEA) co‐oligomers of degree of polymerization 10 with 2, 3, and 4 units of HEA, which were in turn used as multifunctional initiators for the ROP of L ‐lactide, using a bifunctional thiourea organocatalytic system. Furthermore, taking advantage of the living nature of RAFT polymerization, the multifunctional initiators were chain extended with styrene (poly((EA‐co‐HEA)‐b‐styrene) copolymers), and used as initiators for the ROP of L ‐lactide, to yield miktoarm star copolymers. The ROP reactions were allowed to proceed to high conversions (>95%) with good control over molecular weights (ca. 28,000‐230,000 g/mol) and polymer structures being observed, although the molecular weight distributions are generally broader (1.3–1.9) than those normally observed for ROP reactions. The orthogonality of both polymerization techniques, coupled with the ubiquity of HEA, which is used as a monomer for RAFT polymerization and as an initiator for ROP, offer a versatile approach to star‐shaped copolymers. Furthermore, this approach offers a practical approach to the synthesis of polylactide star polymers without a glove box or stringent reaction conditions. The phase separation properties of the miktoarm star copolymers were demonstrated via thermal analyses. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6396–6408, 2009     

Synthesis of hyperbranched degradable polymers by atom transfer radical (Co)polymerization of inimers with ester or disulfide groups

Degradable hyperbranched polymers with multiple alkyl halide chain ends were synthesized by the atom transfer radical polymerization of inimers containing ester (2‐(2′‐bromopropionyloxy)ethyl acrylate) or disulfide (2‐(2′‐bromoisobutyryloxy)ethyl 2′′‐methacryloyloxyethyl disulfide) groups. Both the homo‐ and copolymerizations (with styrene in the former case and methyl methacrylate in the latter) were studied. The hyperbranched polymers derived from the ester‐type inimer were hydrolytically degradable under basic conditions, whereas those derived from the disulfide‐containing inimer could be efficiently degraded in the presence of reducing agents such as tributylphosphine. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009     

Preparation of chiral amino acid materials and the study of their interactions with 1,1‐Bi‐2‐naphthol

The amino acid tryptophan has been converted into acrylamide monomers using L /D ‐tryptophan methyl ester forming the enantiopure chiral monomers. Attempts were made to polymerize these monomers via reversible addition fragmentation chain transfer (RAFT) polymerization to form poly(tryptophan). Unfortunately, this proved difficult, and instead, a postpolymerization modification route was used by first synthesizing poly(pentafluorophenyl acrylate) via RAFT, which was then substituted with L ‐tryptophan methyl ester to give poly(L ‐tryptophan). The interactions of the newly synthesized tryptophan monomers, as well as previously reported phenylalanine monomers, were studied in the presence of rac‐BINOL. It has been shown that the enantiomers of tryptophan have a stronger interaction with BINOL than phenylalanine and this has been attributed to the larger π system on the side chain. By monitoring the shifts and splitting of the phenolic protons of BINOL, it has been observed that S‐BINOL interacts more favorably with L ‐monomer enantiomers and R‐BINOL with D ‐monomer enantiomers. Similar interactions have also been seen with poly(phenylalanine) and the newly synthesized poly(tryptophan) materials. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis,crystal structure,electronic spectroscopy,electrochemistry and biological studies of carbohydrate containing ferrocene amides

A series of four new ferrocene–carbohydrate amides was prepared from pentose and hexose sugar derivatives. These include (5‐amino‐5‐deoxy‐1,2‐O‐isopropylidene‐α‐d ‐xylofuranose)‐1‐ferrocene carboxamide (2a), (5‐amino‐3‐O‐benzyl‐5‐deoxy‐1,2‐O‐isopropylidene‐α‐d ‐xylofuranose)‐1‐ferrocene carboxamide (2b), (methyl‐6‐amino‐6‐deoxy‐2,3‐O‐isopropylidene‐β‐d ‐ribofuranoside)‐1‐ferrocene carboxamide (2c) derived from furanose sugars and (6‐amino‐6‐deoxy‐1,2:3,4‐di‐O‐isopropylidene‐α‐d ‐galactopyranose)‐1‐ferrocene carboxamide (2d) derived from pyranose sugar. The compounds were characterized by spectroscopic means and the structure of amide derived from α‐d ‐xylofuranose (2a) was determined by X‐ray crystallography. The electronic and optical properties of the compounds were studied by means of cyclic voltammetry and absorption spectroscopy. The UV and electrochemical studies of these compounds, performed in aqueous solutions under physiological conditions (at pH 7.4), confirmed their stability. These results indicated that the compounds were suitable for conducting biological studies. The CD spectral analysis displays the effect of sugar substituents on the compounds. The cytotoxicity and antimicrobial activity of these conjugates were investigated on different cancer cell lines and microbes respectively. The degree of inhibition varied over a broad spectrum of Gram‐ positive and Gram‐negative bacteria. In addition, the compounds also exhibited antioxidant properties. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis of lipo‐glycopolymer amphiphiles by nitroxide‐mediated living free‐radical polymerization

The nitroxide‐mediated living free‐radical polymerization of 1,2,5,6‐di(isopropylidene)‐D ‐glucose‐2‐propenoate was achieved in dimethylformamide at 105 °C with an α‐hydrido alkoxyamine initiator functionalized with a lipophilic N,N‐di(octadecyl)amine group. The kinetics of the polymerization were investigated, and the mechanism was shown to be a living process allowing, after hydrolysis, controlled molecular weight, low‐polydispersity lipo‐glycopolymers to be prepared. The amphiphilic character of the macromolecule could be altered by either the exchange of the alkoxyamine at the chain end with hydrogen or the preparation of copolymers with lipophilic monomers such as N,N‐di(octadecyl)acrylamide. The surface and membrane‐forming properties of these novel lipopolymers demonstrate their amphiphilic character. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3379–3391, 2002     

Generation of well‐defined clickable glycopolymers from aqueous RAFT polymerization of isomaltulose‐derived acrylamides

Original carbohydrate‐based acrylamides bearing one azide group in C‐2 or C‐6 position namely, 2‐[(2‐deoxy‐2‐azido‐α‐D ‐mannopyranosyloxy)ethanamido]‐ethyl acrylamide (II) and 2‐[(6‐deoxy‐6‐azido‐α‐D ‐glucopyranosyloxy)ethanamido]‐ethyl acrylamide (III), and their azide‐free analogue, 2‐[(α‐D ‐glucopyranosyloxy)ethanamido]‐ethyl acrylamide (I), have been designed. Whereas the reversible addition fragmentation chain transfer (RAFT) process ensured the preparation of well‐defined glycopolymers from I, the polymerization of monomers II and III proved to be challenging at temperatures compatible with a thermally initiated radical process, due to the presumed concomitant 1,3‐cycloaddition reactions between the azide and the acrylamide moieties. In contrast to III, for which no polymer could be obtained under any conditions, performing the RAFT polymerization of II at 30 °C clearly favored the radical polymerization and conferred a controlled character to the process, affording well‐defined azide‐functionalized glycopolymers and block copolymers. The presence of numerous azide moieties was finally exploited to introduce carbohydrates onto the glycopolymer backbone through copper catalyzed azide‐alkyne cycloaddition. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Chemo-enzymatic Synthesis and RAFT Polymerization of 6-O-Methacryloyl Mannose: A Suitable Glycopolymer for Binding to the Tetrameric Lectin Concanavalin A?

Summary: The chemo-enzymatic synthesis of 6-O-methacryloyl mannose (MaM) glycomonomer was successfully performed for the first time. Subsequent aqueous RAFT polymerization of the monomer yielded well-defined, linear poly(6-O-methacryloyl mannose) (PMaM) glycopolymers without the need for protecting and deprotecting group chemistry. As well as investigating the RAFT polymerization kinetics of this monomer using various initial monomer to chain transfer agent concentration ratios, the protein binding ability of the generated glycopolymer was tested using concanavalin A, a known mannose-residue binding lectin.     

Synthesis and properties of bio‐based polyurethanes bearing hydroxy groups derived from alditols

Four kinds of bio‐based polyurethanes bearing hydroxy groups in the pendants were synthesized by the polyaddition of D ‐mannitol‐ and D,L ‐erythritol‐derived diols (1,2:5,6‐di‐O‐isopropylidene‐D ‐mannitol and 1,2‐O‐isopropylidene‐D,L ‐erythritol) with hexamethylene diisocyanate and methyl (S)‐2,6‐diisocyanatohexanoate and the subsequent deprotection of the isopropylidene groups. They were hydrolyzed much more quickly than the corresponding protected polyurethanes at 50 °C and pH 7.0, although their hydrolytic degradation rate was lower than that of polyurethanes with saccharic and glucuronic lactone groups, which had been reported in our previous articles. The introduction of D ‐mannitol units to the polyether‐polyurethanes containing poly(oxytetramethylene) glycol units also enhanced their hydrolyzibility. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and characters of hyperbranched poly(vinyl acetate) by RAFT polymeraztion

Reversible addition-fragmentation chain transfer (RAFT) polymerization of VAc in the presence of ECTVA, which capable of both reversible chain transferable through a xanthate moiety and propagation via a vinyl group, led to highly branched copolymers by a method analogous to self-condensing vinyl polymerization (SCVP). The ECTVA acted as a vinyl acetate AB^∗ inimer. It was copolymerized with vinyl acetate (VAc) in ratios selected to tune the distribution and length of branches of resulting hyperbranched poly(vinyl acetate). The degree of branching increased with chain ECTVA concentration, as confirmed by NMR spectroscopy. The polymer structure was characterized via MALDI–TOF. Retention of the xanthate compound during the polymerization was evidenced by successful chain extension of a branched (PVAc) macroCTA by RAFT polymerization. The branched PVAc led to better dissolution as compared to linear PVAc, an effect attributed primarily to an increased contribution of end groups.     

Well‐defined glycopolymer amphiphiles for liquid and supercritical carbon dioxide applications

Well‐defined D ‐glucose‐containing glycopolymers, poly(3‐O‐methacryloyl‐1,2 : 5,6‐di‐O‐isopropylidene‐D ‐glucofuranose) (PMAIpGlc), and diblock copolymers of PMAIpGlc with poly(1,1‐dihydroperfluorooctyl methacrylate) (PFOMA) were synthesized by living anionic polymerization in THF at ?78 °C with 1,1‐diphenylhexyllithium in the presence of lithium chloride. The resulting polymers were found to possess predictable molecular weights and very narrow molecular weight distributions (MWD, M_w/M_n ≤ 1.16). Removal of the acetal protective groups from the protected glycopolymer block copolymer was carried out using 90% trifluoroacetic acid at room temperature, yielding a hydrophilic block copolymer with pendant glucose moieties. Both protected (lipophilic/CO₂‐philic) and deprotected (hydrophilic/CO₂‐philic) fluorocopolymers were proved to be CO₂ amphiphiles. Their solubility in CO₂ was heavily influenced by the amphiphilic structure, such as the copolymer compositions and the polarities of sugar block. Light‐scattering studies showed that, after removal of the protective groups, the deprotected block copolymer formed aggregate structures in liquid CO₂ with an average micellar size of 27 nm. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3841–3849, 2001     

RAFT polymerization and thio‐bromo substitution: An efficient way towards well‐defined glycopolymers

Despite an increasing effort to design well‐defined glycopolymers, the convenient synthesis of polymers with higher DPs (>100) and without tedious protection and deprotection steps remains a challenge. Combining the reversible addition fragmentation transfer (RAFT) polymerization and the efficient substitution of primary bromo groups by thiols, we were able to synthesize a set of well‐defined glycopolymers with DPs of up to 115. With the polymerization of the highly reactive monomer (2‐bromoethyl)‐acrylate polymers with low dispersities were obtained that could efficiently be functionalized with various sugar thiol(ate)s. In particular, derivatives of d ‐glucose, d ‐galactose, and d ‐mannose gave excellent degrees of functionalization close to quantitative conversion using only a slight excess of the thiol. This atom efficient synthesis can even be applied for copolymers with acid or base labile components due to the use of unprotected sugar moieties and, hence, the lack of further deprotection steps. Binding studies with the lectin concanavalin A and the subsequent competition studies with α‐d ‐methyl‐mannopyranose (αMeMan) proved the effective binding of these derivatives and revealed a DP‐ and carbohydrate‐dependent clustering and dissolution. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3617–3626     

One‐step synthesis of poly(N‐vinylpyrrolidone)‐b‐poly(l‐lactide) block copolymers using a dual initiator for RAFT polymerization and ROP

Amphiphilic, biocompatible poly(N‐vinylpyrrolidone)‐b‐poly(l ‐lactide) (PVP‐b‐PLLA) block polymers were synthesized at 60 °C using a hydroxyl‐functionalized N,N‐diphenyldithiocarbamate reversible addition–fragmentation chain transfer (RAFT) agent, 2‐hydroxyethyl 2‐(N,N‐diphenylcarbamothioylthio)propanoate (HDPCP), as a dual initiator for RAFT polymerization and ring‐opening polymerization (ROP) in a one‐step procedure. 4‐Dimethylamino pyridine was used as the ROP catalyst for l ‐lactide. The two polymerization reactions proceeded in a controlled manner, but their polymerization rates were affected by the other polymerization process. This one‐step procedure is believed to be the most convenient method for synthesizing PVP‐b‐PLLA block copolymers. HDPCP can also be used for the one‐step synthesis of poly(N‐vinylcarbazole)‐b‐PLLA block copolymers. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1607–1613     

Synthesis and crosslinking of hyperbranched poly(n‐nonyl acrylate) to form organogels

(2‐Bromo‐n‐nonan‐1‐oxycarbonyl)ethyl acrylate was synthesized as an inimer for self‐condensing vinyl polymerization (SCVP) to produce hyperbranched poly(n‐nonyl acrylate), either as a homopolymer or as a copolymer with n‐nonyl acrylate. The inimer was homopolymerized and copolymerized by atom transfer radical polymerization (ATRP) and activator generated by electron transfer ATRP to produce soluble polymers with broad polydispersities (up to ? = 9.91), which is characteristic of hyperbranched polymers produced by SCVP. The resulting hyperbranched (co)polymers were crosslinked by atom transfer radical coupling in both one‐pot and two‐step procedures. The radical–radical crosslinking reaction is extremely efficient, resulting in hard plastic particles from the homopolymer of (2‐bromo‐n‐nonan‐1‐oxycarbonyl)ethyl acrylate synthesized in bulk. Crosslinked organogels that swell in tetrahydrofuran were formed when the rate of crosslinking decreased using acetonitrile solutions. Dynamic shear and stress relaxation experiments demonstrated that the dry network behaves as a covalently crosslinked soft gel, with a glass transition at ?50 °C according to differential scanning calorimetry. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2399–2410     

Synthesis of Hyperbranched Polyethylene Amphiphiles by Chain Walking Polymerization in Tandem with RAFT Polymerization and Supramolecular Self‐Assembly Vesicles

A novel polymerization methodology for efficient synthesis of hyperbranched polyethylene amphiphiles by chain walking polymerization (CWP) followed by RAFT polymerization has been developed. Hyperbranched polyethylene with hydroxyl ends (HBPE‐OHs) is first synthesized via chain walking copolymerization of ethylene with 2‐hydroxyethyl acrylate with Pd‐α‐diimine catalyst. The hydroxyl groups of hyperbranched polyethylene are then converted into thiocarbonyl thio moieties by an esterification reaction with trithiocarbonate 3‐benzylsulfanylthiocarbonyl sulfanylpropionic acid (BSPA). The hyperbranched polyethylene with thiocarbonyl thio moiety ends (HBPE‐BSPAs) is used as a macro‐RAFT agent for the synthesis of hyperbranched polyethylene amphiphiles, HBPE‐PDMAEMAs, by RAFT polymerization of N,N‐dimethylaminoethyl methacrylate (DMAEMA). The resultant HBPE‐PDMAEMAs can self‐assemble to form supramolecular polymer vesicles in aqueous solution. A preliminary investigation on thermo‐ and pH‐responsive behaviors of the polymer is also reported.