Biocompatible,Hemocompatible and Antibacterial Acylated Dextran-g-polyisobutylene Graft Copolymers with Silver Nanoparticles

The novel amphiphilic acylated dextran-g-polyisobutylene (AcyDex-g-PIB) graft copolymers with different branch lengths (Mn,PiB,2600-5800 g/mol) and grafting numbers (GN,5-28 per 1000 Dex monosaccharide) were successfully synthesized via the nucleophilic substitution of the hydroxyl (--OH) side groups along AcyDex backbone by the living PIB-THF4+ chains prepared through cationic polymerization.The crystallization of AcyDex backbone in AcyDex-g-PIB graft copolymers was confined due to the presence of PIB branches and the morphology changed from short rod-like crystals to fragment-like crystals with increasing Mn,PIB and GN.The obvious microphase separation occurred due to the incompatibility between hard AcyDex backbone and soft PIB branches.AcyDex-g-PIB graft copolymers exhibit excellent biocompatibility towards HeLa cells and good hemocompatibility with red blood cells (RBCs),both of which increase with increasing GN.The increases of water contact angle and roughness on the surface of the graft copolymers with increasing Mn,PiB and GN manifest the anti-protein adsorption performance.The amphiphilic AcyDex-g-PIB graft copolymers could self-assemble in aqueous solution into nanospheres,which can be used as pH-sensitive drug carriers and can release 100％ of the loaded drug within 72 h at pH=7.4.AcyDex-g-PIB graft copolymers bearing silver nanoparticles (Ag-NPs,0.8 wt％-3.9 wt％,4.5-9.5 nm) show good antibacterial properties.This kind of amphiphilic graft copolymer would have a promising prospect in biological and medical fields.     

聚谷氨酸苄酯-g-(聚四氢呋喃-b-聚异丁烯)共聚物的微观结构与形态

通过可控/活性离子聚合方法设计合成一系列不同共聚组成的聚谷氨酸苄酯-g-(聚四氢呋喃-b-聚异丁烯)的新型嵌段接枝共聚物,即PBLG-g-(PTHF-b-PIB),研究共聚物中支链(PTHF-b-PIB)长度及接枝密度对主链PBLG玻璃化转变温度、α-螺旋二级结构及其转变的影响,研究支链中PTHF链段长度对其双端受限的玻璃化转变及凝聚态结构的影响.结果表明:PBLG-g-(PTHF-b-PIB)共聚物中刚性主链保持α-螺旋二级结构;随着支链长度增加或接枝密度增加,主链PBLG的α-螺旋二级结构特征峰逐渐减弱,玻璃化转变温度逐渐提高,α-螺旋结构发生转变的焓值逐渐增大;在确定接枝密度的情况下,随着支链中PTHF链段长度增加,共聚物中双端受限的PTHF链段结晶逐渐增强,结晶熔融温度及熔融焓均增加;在确定支链中PTHF链段长度的情况下,随着接枝密度增大,支链间链段相互排斥,PTHF链段结晶逐渐减弱.     

Nanocrystallization-locked Network of Poly(styrene-b-isobutylene-b-styrene)-g-Polytetrahydrofuran Block Graft Copolymer

Poly(styrene-b-isobutylene-b-styrene) triblock copolymer(SIBS), a kind of thermoplastic elastomer with biocompatibility and biostability containing fully saturated soft segments, could be synthesized via living cationic copolymerization. A novel poly[(styrene-comethylstyrene)-b-isobutylene-b-(styrene-co-methylstyrene)]-g-polytetrahydrofuran(M-SIBS-g-PTHF) block graft copolymer was prepared to increase the polarity and service temperature of SIBS by grafting polar PTHF segments onto SIBS. A series of the above block graft copolymers with average grafting numbers from 2 to 6 and molecular weights of PTHF branches ranging from 200 g·mol~(-1) to 4200 g·mol~(-1) were successfully synthesized via living cationic ring-opening polymerization of tetrahydrofuran(THF) coinitiated by AgClO_4. The introduction of PTHF branches led to an obvious microphase separation due to thermodynamic incompatibility among the three kinds of segments of polyisobutylene(PIB),polystyrene(PS) and PTHF. Moreover, the microphase separation promotes the rearrangement of PTHF branches to form the nanocrystallizationlocked physically cross-linked network after storage at room temperature for 2 months, leading to insolubility of the copolymers even in good solvents. The melting temperature and enthalpy of PTHF nanocrystallization locked in hard domains of M-SIBS-g_5-PTHF~(-1).1 k block graft copolymer increased remarkably up to 153 °C and 117.0 J·g~(-1) by 23 °C and 11.6 J·g~(-1) respectively after storage for long time. Storage modulus(G')is higher than loss modulus(G') of M-SIBS-g-PTHF block graft copolymer at temperatures ranging from 100 °C to 180 °C, which is much higher than those of the SIBS triblock copolymer. To the best of our knowledge, this is the first example of high performance M-SIBS-g-PTHF block graft copolymers containing segments of PIB, PS and PTHF with nanocrystallization-locked architecture.     

活性正离子聚合及原位制备聚醋酸乙烯酯-g-聚四氢呋喃共聚物/纳米银复合材料

通过将烯丙基溴/高氯酸银引发体系引发四氢呋喃活性正离子开环聚合与"grafting onto"合成方法相结合,原位制备了不同接枝密度和接枝链长度的新型聚醋酸乙烯酯-g-聚四氢呋喃接枝共聚物(PVAc-g-PTHF)及其与纳米银(Ag)的复合材料.采用傅里叶变换红外光谱(FTIR)、核磁共振波谱(1H-NMR)和多角度激光光散射-黏度-凝胶渗透色谱仪(MALLS-VIS-GPC)分别表征了该接枝共聚物的化学结构、共聚组成、分子量、分子量分布、接枝支链数目及支化度,采用原子力显微镜(AFM)、示差扫描量热分析(DSC)、偏光显微镜(POM)研究了接枝共聚物中接枝支链数目及支链长度对其微观形态、单端受限链段结晶行为的影响,并探讨了该纳米复合材料的抗菌性能.结果表明:所制备的不同支链数目和支链长度的PVAc-g-PTHF/Ag纳米复合材料,均表现出良好的抗菌性能;接枝共聚物PVAc-g-PTHF的重均分子量可达4.52×10~5,分子分子量较窄(M_w/M_n~1.8),支化因子可达0.19.接枝共聚物PVAc-g-PTHF可形成明显的相分离结构,其微观形态与接枝支链数目有关;相比相同分子量的双端不受限的PTHF链,PVAc-g-PTHF接枝共聚物中单端受限PTHF支链的结晶速率明显降低;在确定接枝支链数目的情况下,随着支链中PTHF链段长度增加,其结晶逐渐增强,结晶熔融温度及熔融焓均稍有增加.     

Synthesis of well‐defined comb‐like graft (co)polymers by nucleophilic substitution reaction between living polymers and polyhalohydrocarbon

A series of graft (co)polymers were synthesized by nucleophilic substitution reaction between iodinated 1,2‐polybutadiene (PB‐I, backbone) and living polymer lithium (side chains). The coupling reaction between PB‐I and living polymers can finish within minutes at room temperature, and high conversion (up to 92%) could be obtained by effectively avoiding side reaction of dimerization when living polymers were capped with 1,1‐diphenylethylene. By virtue of living anionic polymerization, backbone length, side chain length, and side chain composition, as well as graft density, were well controlled. Tunable molecular weight of graft (co)polymers with narrow molecular weight distribution can be obtained by changing either the lengths of side chain and backbone, or the graft density. Graft copolymers could also be synthesized with side chains of multicomponent polymers, such as block polymer (polystyrene‐b‐polybutadiene) and even mixed polymers (polystyrene and polybutadiene) as hetero chains. Thus, based on living anionic polymerization, this work provides a facile way for modular synthesis of graft (co)polymers via nucleophilic substitution reaction between living polymers and polyhalohydrocarbon (PB‐I). © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Amphiphilic Graft Copolymers as Phase-Transfer Catalysts in a Solid-Liquid System

Abstract

Amphiphilic graft copolymers consisting of a hydrophobic backbone and poly(oxyethylene) (PEO) side chains were employed as solidliquid phase-transfer catalysts (PTC) in the substitution of octylbromide by solid potassium phenoxide in toluene. A wide variety of structures were synthesized via ester substitution of poly(phthalimidoacrylate) (PPIA) or poly(phthalimidoacrylate-co-styrene) [poly(PIA-co-St)] with amino-functionalized methoxy-PEO (MPEO-NH₂). The phase-transfer catalytic activity (PTA) of these soluble graft copolymers was studied as a function of the structure of the backbone, the length of the side chains, and the graft density. The graft copolymers of a high degree of grafting showed PTA higher than that of parent PEOs. GPC was used to study the behavior of the graft copolymers in toluene at 90°C. It is believed that the phase-transfer reaction is accelerated in the PEO microphase.     

Aggregate morphologies of amphiphilic graft copolymers in dilute solution studied by self-consistent field theory

Microstructures assembled by amphiphilic graft copolymers in a selective solvent (poor for the backbone chain and good for graft chains or poor for graft chains and good for the backbone chain) were investigated on the basis of a real-space algorithm of self-consistent field theory in two-dimensions. Circle-like micelles, line-like micelles, large compound micelles, and vesicles are obtained by tailoring the architectural parameters and interaction parameter between the graft blocks and solvents. The aggregate morphology stability regions of graft copolymers as functions of the position of first graft point and the number of branches are constructed. It is found that the architectural parameters play a remarkable role in the complex microstructure formation. The interaction between the graft blocks and solvents is also shown to exert an effect on the morphology stability regions. The distributions of the free end and inner blocks of the backbone are found to be different in various aggregate structures. For the circle-like micelles assembled by graft copolymers with a hydrophobic backbone and vesicles assembled by graft copolymers with a hydrophilic backbone, the free end and inner blocks segregate and localize in different parts of the aggregates depending on their length. However, with respect to the large compound micelles and vesicles assembled by graft copolymers with a hydrophobic backbone, the free end and inner blocks uniformly mix in the clusters.     

Synthesis of comb-shaped polymers via controlled cationic polymerization of oxazolines with polyester-type macroinitiator

On the basis of macroinitiators of polyester type, hybrid comb-shaped polymers with poly-2-isopropyl-2-oxazoline side fragments are prepared via ring-opening cationic polymerization. A method for estimating the length of polyoxazoline side chains and their grafting density is proposed. It is shown that, at the given ratio of the length of backbone and side chains, which depends on the chemical structure of the initiator, the graft copolymers are capable of formation of micellar aqueous solutions with a lower critical solution temperature.     

PNIPAM‐b‐(PEA‐g‐PDMAEA) double‐hydrophilic graft copolymer: Synthesis and its application for preparation of gold nanoparticles in aqueous media

A series of well‐defined double‐hydrophilic graft copolymers, consisting of poly(N‐isopropylacrylamide)‐b‐poly(ethyl acrylate) (PNIPAM‐b‐PEA) backbone and poly(2‐(dimethylamino)ethyl acrylate) (PDMAEA) side chains, were synthesized by the combination of single‐electron‐transfer living radical polymerization (SET‐LRP) and atom‐transfer radical polymerization (ATRP). PNIPAM‐b‐PEA backbone was first prepared by sequential SET‐LRP of N‐isopropylacrylamide and 2‐hydroxyethyl acrylate at 25 °C using CuCl/tris(2‐(dimethylamino)ethyl)amine as catalytic system followed by the transformation into the macroinitiator by treating the pendant hydroxyls with 2‐chloropropionyl chloride. The final graft copolymers with narrow molecular weight distributions were synthesized by ATRP of 2‐(dimethylamino)ethyl acrylate initiated by the macroinitiator at 40 °C using CuCl/tris(2‐(dimethylamino)ethyl)amine as catalytic system via the grafting‐from strategy. These copolymers were employed to prepare stable colloidal gold nanoparticles with controlled size in aqueous solution without any external reducing agent. The morphology and size of the nanoparticles were affected by the length of PDMAEA side chains, pH value, and the feed ratio of the graft copolymer to HAuCl₄. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1811–1824, 2009     

Synthesis of PCL–graft–PS by combination of ROP, ATRP, and click chemistry

Poly(ε-caprolactone)–graft–polystyrenes were successfully synthesized by grafting an azide end-functionalized polystyrene onto a PCL backbone with multiple pendant alkyne moieties using a “click” chemistry reaction. Both precursors, the PCL backbone and the PS side chains, were prepared separately by two different living/controlled mechanisms, ring-opening polymerisation and ATRP, respectively. Molecular weights, polydispersity indexes, and chemical compositions of the backbone and branches were controlled. The subsequent copper-catalysed Huisgen 1,3-dipolar cycloaddition of PS onto PCL was achieved at room temperature with high conversion. However, a bimodal molecular weight distribution was observed in size exclusion chromatography due to the presence of unreacted PS. Nevertheless, crude product was purified by selective fractionation in cyclohexane to achieve pure graft copolymers.     

Reactions of living polystyrene with difunctional nitriles to produce specifically placed grafting sites

Graft polymers have been synthesized with two equal length branches and one or two branches of a different length or composition. The first step was a coupling reaction of living polystyrene with a difunctional nitrile. The product was hydrolyzed to form a ketone-containing backbone. Subsequently another sample of living polystyrene or of poly-2-vinylpyridine was added to the backbone to form the graft. Anionic polymerization was used for the synthesis of backbone and side chains, so all of the products are well defined. The products and reaction sequences also serve as models for a general synthesis of well-defined comb-shaped polymers, in which the length of the backbone, and the number, length, and spacing of the side chains may be controlled.     

Synthesis of poly(styrene-graft-ethylene oxide) by ethoxylation of amide group containing styrene copolymers

Graft copolymers containing poly(ethylene oxide) side chains on a polystyrene backbone have been synthesized. Styrene copolymers synthesized by free radical mechanism and containing between 5 and 15 mol % acrylamide or methacrylamide were used as backbones. The amide groups in the copolymers were ionized by using potassium tert-butoxide or potassium naphthalene, and grafting was achieved by utilizing the amide anions as initiator sites for the polymerization of ethylene oxide in 2-ethoxyethyl ether at 65°C. The graft copolymers were characterized with respect to molecular weight and composition using elemental analysis, NMR, gel permeation chromatography, IR, and viscosity measurements. The size of the side chains were between 600 and 2000 g/mol. GPC results from a hydrolyzed graft copolymer sample suggest a narrow size distribution for the poly(ethylene oxide) grafts. Solution properties of the graft copolymers were investigated in different toluene/methanol mixtures. The intrinsic viscosities of the graft copolymers were found to depend primarily on the poly(ethylene oxide) content rather than the graft density or the poly(ethylene oxide) chain length. © 1993 John Wiley & Sons, Inc.     

Smart assembly behaviors of hydroxypropylcellulose-graft-poly(4-vinyl pyridine) copolymers in aqueous solution by thermo and pH stimuli

Thermo- and pH-sensitive graft copolymers, hydroxypropylcellulose-graft-poly(4-vinyl pyridine) (HPC-g-P4VP), were synthesized via atom transfer radical polymerization (ATRP) and characterized. The thermo- and pH-induced micellization and stimuli-responsive properties of HPC-g-P4VP graft copolymers in aqueous solution were investigated by transmittance, (1)H NMR, dynamic light scattering (DLS), and so on. For the pH-induced micellization, the P4VP side chains collapse to form the core of the micelles, and the HPC backbones stay in the shell to stabilize the micelles. In the case of thermoinduced micellization, the HPC backbones collapse to form the core of the micelles that was stabilized by the P4VP side chains in the shell upon heating. What's more, the cloud point of the HPC-g-P4VP copolymers in the aqueous solution could be finely tuned by changing the length of P4VP side chains or the pH values. In acidic water, the longer the side chains, the higher the cloud point. For those HPC-g-P4VP copolymers with short side chains, for example, HPC0.05-g-P4VP(3), the lower pH correlates a higher cloud point. The thermo- or pH-induced micelles also have the pH- or thermosensitivity due to their P4VP or HPC shells.     

Successive SET‐LRP and ATRP synthesis of ferrocene‐based PPEGMEA‐g‐PAEFC well‐defined amphiphilic graft copolymer

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     

Solution behavior of polyimide‐graft‐polystyrene copolymers in selective solvents

A polyimide‐graft‐polystyrene (PI‐g‐PS) copolymer with a polyimide backbone and polystyrene side chains was synthesized by the “grafting from” method using styrene polymerization on a polyimide multicenter macroinitiator via ATRP mechanism. The side chain grafting density z = 0.86 of PI‐g‐PS is rather high for graft‐copolymers synthesized by the ATRP method. Molecular characteristics and solution behavior of PI‐g‐PS were studied in selective solvents using light scattering and viscometry methods. In all solvents, the backbone tends to avoid contact with a poor solvent. To describe the conformation and hydrodynamic properties of PI‐g‐PS macromolecules in thermodynamically good solvents for side chains and PI‐g‐PS, the wormlike spherocylinder model is used. Macromolecules of the studied graft‐copolymer are characterized by high equilibrium rigidities (Kuhn segment length >20 nm). In Θ‐conditions, PI‐g‐PS macromolecules may be modeled by a rigid prolate ellipsoid of revolution with a low asymmetry form and a collapsed backbone as the ellipsoid core. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1539–1546     

Chitosan-graft-poly(ϵ-caprolactone)s: An optimized chemical approach leading to a controllable structure and enhanced properties

A novel synthetic approach was developed for the controllable modification of chitosan (CS) with poly(ϵ-caprolactone) (PCL). 6-O-Triphenylmethyl-chitosan (TMCS) was synthesized as a highly soluble intermediate in organic solvents to facilitate an efficient grafting reaction of PCL onto CS in a homogeneous reaction medium. Subsequently, the syntheses of CS-g-PCL copolymers with different degrees of substitution (ds) and various chain lengths of PCL (number-average molecular weight = 1200–11,000) were carried out by a coupling reaction between the carboxylic terminal groups of PCL chains and the amino groups of TMCS. The successful grafting reaction was confirmed by GPC measurements, which indicated that the products were graft copolymers rather than physical blends. The ds, defined as the number of PCL chains per saccharide unit, of the graft copolymers could be adjusted simply by changes in the molar feed ratios of PCL to CS, and graft copolymers with different ds values ranging from 0.28 to 0.49 were synthesized, as calculated by ¹H NMR and elemental analysis. DSC and X-ray measurements showed that the melting temperature and enthalpy of the PCL grafts of these graft copolymers could be adjusted by the ds and the chains length of PCL, respectively. Meanwhile, the CS-g-PCL copolymers exhibited better solubility in various solvents, such as in chloroform for some of the resultant graft copolymers, than the original CS. Finally, nanoparticles of 100–200 nm, having hydrophobic PCL domains and cationic hydrophilic surfaces, were obtained through the self-assembly of the copolymers in selective solvents. These types of graft copolymers have great potential in various applications, such as targeted drug and gene delivery as well as tissue engineering. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2556–2568, 2007     

Synthesis and Properties of SEPS-<Emphasis Type="Italic">g</Emphasis>-PEO Copolymers with Varying Branch Lengths

Poly(ethylene oxide) (PEO) was controllably grafted from styrene-b-(ethylene-co-propylene)-b-styrene (SEPS) backbones by combining lithiation of styrenic units and living monomer-activated anionic ring-opening polymerization of ethylene oxide (EO)monomers with the aid of co-initiators triisobutyl aluminum.The as-synthesized SEPS-g-PEO copolymers were characterized by SEC,1H-NMR,FTIR,SAXS,AFM and DSC.When the branch length is relatively small,increase of PEO fraction leads to the increase of the correlation length between neighboring hard domains,but the degree of correlation reduces.When the branch length is relatively large,the phase-separated structures become random both in terms of size and spatial correlation,and macro-phase separated structures appear.The crystallization behavior of the PEO branches can be effectively inhibited in SEPS-g-PEO,so no significant crystallization takes place until the fraction of PEO branches is 20.1 wt％,which greatly promotes the rapid delivery of hydrophilic drugs in the hot-melting pressuresensitive adhesives (HMPSAs) based on SEPS-g-PEO.Their cumulative release amount of a model drug could achieve 80％,more than twice the value in the HMPSAs based on linear PEO-containing styrenic block copolymers.     

Unprecedented diverse nanostructures formed by amphiphilic graft copolymer bearing PEO side chains synthesized by ATNRC

A series of well‐defined amphiphilic graft copolymers bearing hydrophilic poly(ethylene oxide) (PEO) side chains with tunable grafting densities were synthesized by atom transfer nitroxide radical coupling (ATNRC) reaction using CuBr/PMDETA as catalytic system via the grafting‐onto strategy. PEO side chains were linked to α‐C of carbonyl of polyacrylate‐based backbone, not to the ester side groups as usual, so that every repeating unit of the backbone possessed a pendant steric bulky tert‐butyl group. The critical micelle concentrations of the obtained amphiphilic graft copolymers in aqueous media determined by fluorescence probe technique using pyrene as probe increased with the raising of molecular weights. These amphiphilic graft copolymers with novel chemical structure showed unprecedented diverse nanostructures visualized by transmission electron microscopy in aqueous media and micellar morphologies varied with the changing of experiment parameters. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Novel amphiphilic graft copolymers bearing hydrophilic poly(acrylic acid) backbones and hydrophobic poly(butyl methacrylate) side chains

A novel amphiphilic graft copolymer consisting of hydrophilic poly(acrylic acid) backbones and hydrophobic poly(butyl methacrylate) side chains was synthesized by successive atom transfer radical polymerization followed by hydrolysis of poly‐(methoxymethyl acrylate) backbone. A grafting‐from strategy was employed for the synthesis of graft copolymers with narrow molecular weight distributions (polydispersity index < 1.40). Hydrophobic side chains were connected to the backbone through stable C? C bonds instead of ester connections. Poly(methoxymethyl acrylate) backbone was easily hydrolyzed to poly(acrylic acid) backbone with HCl without affecting the hydrophobic side chains. The amphiphilic graft copolymer could form stable micelles in water. The critical micelle concentration in water was determined by a fluorescence probe technique. The morphology of the micelles was preliminarily explored with transmission electron microscopy and was found to be spheres. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6857–6868, 2006     

Amphiphilic PEG‐grafted poly(ester‐carbonate)s: Synthesis and diverse nanostructures in water

Novel biodegradable amphiphilic graft copolymers containing hydrophobic poly(ester‐carbonate) backbone and hydrophilic poly(ethylene glycol) (PEG) side chains were synthesized by a combination of ring‐opening polymerization and “click” chemistry. First, the ring‐opening copolymerization of 5,5‐dibromomethyl trimethylene carbonate (DBTC) and ε‐caprolactone (CL) was performed in the presence of stannous octanoate [Sn(Oct)₂] as catalyst, resulting in poly(DBTC‐co‐CL) with pendant bromo groups. Then the pendant bromo groups were completely converted into azide form, which permitted “click” reaction with alkyne‐terminated PEG by Huisgen 1,3‐dipolar cycloadditions to give amphiphilic biodegradable graft copolymers. The graft copolymers were characterized by proton nuclear magnetic resonance (¹H NMR), Fourier transform infrared spectra and gel permeation chromatography measurements, which confirmed the well‐defined graft architecture. These copolymers could self‐assemble into micelles in aqueous solution. The size and morphologies of the copolymer micelles were measured by transmission electron microscopy and dynamic light scattering, which are influenced by the length of PEG and grafting density. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.