A novel drug-polymer conjugate was prepared by the copper-catalyzed azide–alkyne cycloaddition reaction between an azide-functional diblock copolymer and an alkyne-functional paclitaxel (PTX). The well-defined azide-functional diblock copolymer, poly(ethylene glycol) (PEG)-b-P(OEGEEMA-co-AzPMA), was synthesized via the atom transfer radical polymerization of oligo(ethylene glycol) ethyl ether methacrylate (OEGEEMA) and 3-azidopropyl methacrylate (AzPMA), using PEG-Br as macroinitiator and CuBr/PMDETA as a catalytic system. The alkyne-functional PTX was covalently linked to the copolymer via a click reaction, and the loading content of PTX could be easily tuned by varying the feeding ratio. Transmission electron microscopy and dynamic light scattering results indicated that the drug loaded copolymers could self-assemble into micelles in aqueous solution. Moreover, the drug release behavior of PEG-b-P(OEGEEMA-co-AzPMA-PTX) was pH dependent, and the cumulative release amount of PTX were 50.0% at pH 5.5, which is about two times higher than that at pH 7.4. The in vitro cytotoxicity experimental results showed that the diblock copolymer was biocompatible, with no obvious cytotoxicity, whereas the PTX-polymer conjugate could efficiently deliver PTX into HeLa and SKOV-3 cells, leading to excellent antitumor activity. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 366–374

A series of ferrocene-based well-defined amphiphilic graft copolymers, consisting of hydrophilic poly[poly(ethylene glycol) methyl ether acrylate] (PPEGMEA) backbone and hydrophobic poly(2-acryloyloxyethyl ferrocenecarboxylate) (PAEFC) side chains were synthesized by successive single-electron-transfer living radical polymerization (SET-LRP) and atom transfer radical polymerization (ATRP). The backbone was prepared by SET-LRP of PEGMEA macromonomer, and it was then treated with lithium di-isopropylamide and 2-bromopropionyl bromide at −78 °C to give PPEGMEA-Br macroinitiator. The targeted well-defined graft copolymers with narrow molecular weight distributions (M_w/M_n ≤ 1.32) were synthesized via ATRP of AEFC initiated by PPEGMEA-Br macroinitiator, and the molecular weights of the backbone and side chains were both controllable. The electro-chemical behaviors of graft copolymers were studied by cyclic voltammetry, and it was found that graft copolymers were more difficult to be oxidized, and the reversibility of electrode process became less with raising the content of PAEFC segment. The effects of the preparation method, the length of hydrophobic PAEFC segment, and the initial water content on self-assembly behavior of PPEGMEA-g-PAEFC graft copolymers in aqueous media were investigated by transmission electron microscopy. The morphologies of micelles could transform from cylinders to spheres or rods with changing the preparation condition and the length of side chains. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

In this study, we report a mild and efficient strategy for growing thermosensitive polymers directly from the surface of exfoliated graphene oxide (GO). Exfoliated GO sheets were sequentially subject to the epoxide ring-opening reaction with tris(hydroxymethyl) aminomethane (TRIS) to increase the amount of reactive sites, the esterification with 2-bromo-2-methylpropionyl bromide to introduce the Br-containing initiating groups, and the surface-initiated single electron transfer–living radical polymerization of N-isopropylacrylamide (NIPAM) to tune the molecular weights of grafted polymers. All these reactions were performed at ambient temperature without losing any other oxygen-containing functionality on GO. The resulting TRIS-GO-PNIPAM nanocomposites still maintain the separated single layers in dispersion, and the dispersibilities in organic solvents are significantly improved. Meanwhile, the aqueous dispersion of TRIS-GO-PNIPAM shows reversible temperature switching self-assembly and disassembly behavior at about 40°C. Such smart graphene-based hybrid materials are promising for applications in nanoelectronics, sensors, and microfluidic switches. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

A series of well-defined double hydrophilic graft copolymers containing poly(poly(ethylene glycol) methyl ether acrylate) (PPEGMEA) backbone and poly(2-vinylpyridine) (P2VP) side chains were synthesized by successive single electron transfer living radical polymerization (SET-LRP) and atom transfer radical polymerization (ATRP). The backbone was first prepared by SET-LRP of poly(ethylene glycol) methyl ether acrylate (PEGMEA) macromonomer using CuBr/tris(2-(dimethylamino)ethyl)amine as catalytic system. The obtained homopolymer then reacted with lithium diisopropylamide and 2-chloropropionyl chloride at −78 °C to afford PPEGMEA-Cl macroinitiator. poly(poly(ethylene glycol) methyl ether acrylate)-g-poly(2-vinylpyridine) double hydrophilic graft copolymers were finally synthesized by. ATRP of 2-vinylpyridine initiated by PPEGMEA-Cl macroinitiator at 25 °C using CuCl/hexamethyldiethylenetriamine as catalytic system via the grafting- from strategy. The molecular weights of both the backbone and the side chains were controllable and the molecular weight distributions kept relatively narrow (M_w/M_n ≤ 1.40). pH-Responsive micellization behavior was investigated by ¹H NMR, dynamic light scattering, and transmission electron microscopy and this kind of double hydrophilic graft copolymer aggregated to form micelles with P2VP-core while pH of the aqueous solution was above 5.0. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

A series of well-defined amphiphilic graft copolymers bearing hydrophobic poly(tert-butyl acrylate) backbone and hydrophilic poly[poly(ethylene glycol) methyl ether methacrylate)] (PPEGMEMA) side chains were synthesized by sequential reversible addition fragmentation chain transfer (RAFT) polymerization and single-electron-transfer living radical polymerization (SET-LRP) without any polymeric functional group transformation. A new Br-containing acrylate monomer, tert-butyl 2-((2-bromoisobutanoyloxy)methyl)acrylate (tBBIBMA), was first prepared, which can be homopolymerized by RAFT to give a well-defined PtBBIBMA homopolymer with a narrow molecular weight distribution (M_w/M_n = 1.15). This homopolymer with pendant Br initiation group in every repeating unit initiated SET-LRP of PEGMEMA at 45 °C using CuBr/dHbpy as catalytic system to afford well-defined PtBBIBMA-g-PPEGMEMA graft copolymers via the grafting-from strategy. The self-assembly behavior of the obtained graft copolymers in aqueous media was investigated by fluorescence spectroscopy and TEM. These copolymers were found to be stimuli-responsive to both temperature and ions. Finally, poly(acrylic acid)-g-PPEGMEMA double hydrophilic graft copolymers were obtained by selective acidic hydrolysis of hydrophobic PtBA backbone while PPEGMEMA side chains kept inert. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

A series of well-defined double hydrophilic graft copolymers, consisting of poly(N-isopropylacrylamide)-b-poly(ethyl acrylate) backbone and poly(2-vinylpyridine) side chains, were synthesized by successive single-electron-transfer living radical polymerization (SET-LRP) and atom transfer radical polymerization (ATRP). The backbone was prepared by sequential SET-LRP of N-isopropylacrylamide and 2-hydroxyethyl acrylate at 25 °C using CuCl/tris(2-(dimethylamino)ethyl)amine as the catalytic system. The obtained diblock copolymer was transformed into the macroinitiator by reacting with 2-chloropropionyl chloride. Next, grafting-from strategy was used for the synthesis of poly(N-isopropylacrylamide)-b-[poly(ethyl acrylate)-g-poly(2-vinylpyridine)] double hydrophilic graft copolymer. ATRP of 2-vinylpyridine was initiated by the macroinitiator at 25 °C using CuCl/hexamethyldiethylenetriamine as the catalytic system. The synthesis of both the backbone and the side chains are controllable. Thermo- and pH-responsive schizophrenic micellization behaviors were investigated by ¹H NMR, fluorescence spectroscopy, dynamic light scattering, and transmission electron microscopy. Unimolecular micelles with PNIPAM-core formed in acidic environment (pH = 2) with elevated temperature (T ≥ 32 °C), whereas the aggregates turned into spheres with PEA-g-P2VP-core accompanied with the lifting of pH values (pH ≥ 5.3) at room temperature. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 15–23, 2010

A series of well-defined amphiphilic graft copolymers, containing hydrophilic poly(acrylic acid) backbone and hydrophobic poly(butyl acrylate) side chains, were synthesized by sequential reversible addition fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP) without any postpolymerization functionality modification followed by selective acidic hydrolysis of poly(tert-butyl acrylate) backbone. tert-Butyl 2-((2-bromopropanoyloxy)methyl)-acrylate was first homopolymerized or copolymerized with tert-butyl acrylate by RAFT in a controlled way to give ATRP-initiation-group-containing homopolymers and copolymers with narrow molecular weight distributions (M_w/M_n < 1.20) and their reactivity ratios were determined by Fineman-Ross and Kelen-Tudos methods, respectively. The density of ATRP initiation group can be regulated by the feed ratio of the comonomers. Next, ATRP of butyl acrylate was directly initiated by these macroinitiators to synthesize well-defined poly(tert-butyl acrylate)-g-poly(butyl acrylate) graft copolymers with controlled grafting densities via the grafting-from strategy. PtBA-based backbone was selectively hydrolyzed in acidic environment without affecting PBA side chains to provide poly(acrylic acid)-g-poly(butyl acrylate) amphiphilic graft copolymers. Fluorescence probe technique was used to determine the critical micelle concentrations in aqueous media and micellar morphologies are found to be spheres visualized by TEM. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2622–2630, 2010

A series of well-defined amphiphilic star graft copolymers consisting of hydrophilic poly(acrylic acid) backbone and hydrophobic poly(propylene oxide) side chains were synthesized by the sequential reversible addition-fragmentation chain transfer (RAFT) polymerization and atom transfer nitroxide radical coupling (ATNRC) or single electron transfer-nitroxide radical coupling (SET-NRC) reaction followed by the selective hydrolysis of poly(tert-butyl acrylate) backbone. A Br-containing acrylate monomer, tert-butyl 2-((2-bromopropanoyloxy)methyl)acrylate, was first homopolymerized via RAFT polymerization using a new star-like chain-transfer agent with four arms in a controlled way to give a well-defined star-like backbone with a narrow molecular weight distribution (M_w/M_n = 1.23). The grafting-onto strategy was used to synthesize the well-defined PtBA-g-PPO star graft copolymers with narrow molecular weight distributions (M_w/M_n = 1.14–1.25) via ATNRC or SET-NRC reaction between the Br-containing PtBA-based star-like backbone and poly(propylene oxide) with 2,2,6,6-tetramethylpiperidine-1-oxyl end group using CuBr/PMDETA or Cu/PMDETA as catalytic system. PAA-g-PPO amphiphilic star graft copolymers were obtained by the selective acidic hydrolysis of star-like PtBA-based backbone in acidic environment without affecting the side chains. The critical micelle concentrations in aqueous media and brine were determined by the fluorescence probe technique. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2084–2097, 2010

A new amphiphilic graft copolymer containing hydrophilic poly(acrylic acid) backbone and hydrophobic poly(vinyl acetate) side chains was synthesized via sequential atom transfer radical polymerization (ATRP) followed by selective hydrolysis of poly(methoxymethyl acrylate) backbone. Grafting-from strategy was employed to synthesize PMOMA-g-PVAc graft copolymer (M_w/M_n=1.64) via ATRP. The final PAA-g-PVAc amphiphilic graft copolymer was obtained by selective acidic hydrolysis of PMOMA backbone in acidic environment without affecting the side chains. The critical micelle concentrations (cmc) in aqueous media were determined by a fluorescence probe technique. The micelle morphologies were found to be spheres.

A series of well-defined amphiphilic graft copolymers containing hydrophilic poly(acrylic acid) (PAA) backbone and hydrophobic poly(vinyl acetate) (PVAc) side chains were synthesized via sequential reversible addition-fragmentation chain transfer (RAFT) polymerization followed by selective hydrolysis of poly(tert-butyl acrylate) backbone. A new Br-containing acrylate monomer, tert-butyl 2-((2-bromopropanoyloxy)methyl) acrylate, was first prepared, which can be polymerized via RAFT in a controlled way to obtain a well-defined homopolymer with narrow molecular weight distribution (M_w/M_n = 1.08). This homopolymer was transformed into xanthate-functionalized macromolecular chain transfer agent by reacting with o-ethyl xanthic acid potassium salt. Grafting-from strategy was employed to synthesize PtBA-g-PVAc well-defined graft copolymers with narrow molecular weight distributions (M_w/M_n < 1.40) via RAFT of vinyl acetate using macromolecular chain transfer agent. The final PAA-g-PVAc amphiphilic graft copolymers were obtained by selective acidic hydrolysis of PtBA backbone in acidic environment without affecting the side chains. The critical micelle concentrations in aqueous media were determined by fluorescence probe technique. The micelle morphologies were found to be spheres. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6032–6043, 2009

A series of well-defined ferrocene-based amphiphilic graft copolymers, consisting of poly(N-isopropylacrylamide)-b-poly(ethyl acrylate) (PNIPAM-b-PEA) backbone and poly(2-acryloyloxyethyl ferrocenecarboxylate) (PAEFC) side chains, were synthesized by the combination of single-electron-transfer living radical polymerization (SET-LRP) and atom transfer radical polymerization (ATRP). A new ferrocene-based monomer, 2-(acryloyloxy)ethyl ferrocenecarboxylate (AEFC), was prepared first and it can be polymerized via ATRP in a controlled way using methyl 2-bromopropionate as initiator and CuBr/PMDETA as catalytic system in DMF at 40 °C. PNIPAM-b-PEA backbone was synthesized by sequential SET-LRP of NIPAM and HEA at 25 °C using CuCl/Me₆TREN as catalytic system followed by the transformation into the macroinitiator by treating the pendant hydroxyls with α-bromoisobutyryl bromide. The targeted well-defined graft copolymers with narrow molecular weight distributions (M_w/M_n < 1.20) were synthesized via ATRP of AEFC initiated by the macroinitiator. The electro-chemical behaviors of PAEFC homopolymer and PNIPAM-b-(PEA-g-PAEFC) graft copolymer were studied by cyclic voltammetry. Micellar properties of PNIPAM-b-(PEA-g-PAEFC) were investigated by transmission electron microscopy and dynamic light scattering. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4346–4357, 2009

A series of well-defined double hydrophilic double-grafted copolymers, consisting of polyacrylate backbone, hydrophilic poly(2-(diethylamino)ethyl methacrylate) and poly(ethylene glycol) side chains, were synthesized by successive atom transfer radical polymerization. The backbone, poly[poly(ethylene glycol) methyl ether acrylate] (PPEGMEA) comb copolymer, was firstly prepared by ATRP of PEGMEA macromonomer via the grafting-through route followed by reacting with lithium diisopropylamide and 2-bromopropionyl chloride to give PPEGMEA-Br macroinitiator of ATRP. Finally, poly[poly(ethylene glycol) methyl ether acrylate]-g-poly(2-(diethylamino)ethyl methacrylate) graft copolymers were synthesized by ATRP of 2-(diethylamino)ethyl methacrylate using PPEGMEA-Br macroinitiator via the grafting-from route. Poly(2-(diethylamino)ethyl methacrylate) side chains were connected to polyacrylate backbone through stable CC bonds instead of ester connections, which is tolerant of both acidic and basic environment. The molecular weights of both backbone and side chains were controllable and the molecular weight distributions kept relatively narrow (M_w/M_n ≤ 1.39). The results of fluorescence spectroscopy, dynamic laser light scattering and transmission electron microscopy showed this double hydrophilic copolymer was stimuli-responsive to both pH and salinity. It can aggregate to form reversible micelles in basic surroundings which can be conveniently dissociated with the addition of salt at room temperature. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3142–3153, 2009