ATRP法合成弹性蛋白接枝共聚物及其性能研究

弹性蛋白经α-溴异丁酰溴化制备了大分子ATRP引发剂溴化弹性蛋白(E-Br), 再以E-Br作为引发剂, 在CuCl/2,2-联吡啶催化体系下, 用原子转移自由基聚合方法合成了弹性蛋白-g-聚甲基丙烯酸-β-羟乙酯接枝聚合物. 用红外光谱(FTIR)、X射线光电子能谱(XPS)、热重分析(TGA)、扫描电镜(SEM)、离子色谱和动态接触角对接枝聚合物进行了表征. 结果表明, PHEMA键接到了弹性蛋白表面; SEM显示接枝改性后弹性蛋白的表面比未改性前光滑, 但改性后样品的热性能均比未改性样品的低, 起始热分解温度由改性前的307 ℃变为265 ℃; 动态接触角实验结果表明, 接枝改性后的样品具有良好的亲水性, 反应72 h后, 其前进角由接枝前的130.45°下降到29.80°.     

表面等离子体共振光谱研究蛋白质-高分子结合体在金表面的自组装

研究了蛋白质-高分子结合体在金片表面的自组装行为.首先制备了一种引发剂2-溴-2-甲基丙酸-2-氨氧基乙酯(ABM),该引发剂可以与5′-磷酸吡哆醛(PLP)活化的牛血清白蛋白(BSA)的氮端相连,进而得到大分子引发剂BSA-Br.最后以甲基丙烯酸寡聚乙二醇酯(OEGMA)为单体,利用原子转移自由基聚合法(ATRP)制备BSA-POEGMA结合体.利用红外光谱(FTIR)、紫外可见分光光度计(UV-Vis)、基质辅助激光解析串联飞行时间质谱仪(MALDI-TOF-MS)对各步产物进行表征.利用表面等离子体共振光谱(SPR)研究BSA-POEGMA结合体在金片表面的自组装行为,以及金片表面吸附的BSA-POEGMA结合体对其他蛋白质包括溶菌酶(Lys)和纤维蛋白原(Fib)的吸附效果影响.     

窄分布聚丙烯酸-g-聚甲基丙烯酸酯接枝共聚物的合成

利用合成的一种新型原子转移自由基聚合大分子引发剂和从主干接枝的方法制备了窄分布的两亲性接枝共聚物聚丙烯酸-g-聚甲基丙烯酸酯, 并对其结构进行表征. 产物主链和侧链的分子量可分别通过调整单体与引发剂的投料比和反应时间进行控制, 结构规整, 侧链单体适用范围广. 该合成方法不仅推动了接枝共聚物合成研究的进展, 其产物更为两亲性接枝共聚物自组装行为的研究提供了很好的研究对象.     

氢化松香与HEMA酯化物自聚与共聚研究

用氢化松香(HR)与甲基丙烯酸-2-羟乙酯(HEMA)进行酯化反应,得到了酯化物(HRH),然后对其进行了在甲苯中的自由基自聚反应、以及与甲基丙烯酸甲酯(MMA)或与苯乙烯(St)的共聚反应,制备了自聚物和共聚物,用IR和核磁共振氢谱(1HNMR)对产物进行了表征,用综合热分析仪表征了产物的热稳定性和玻璃化转变温度.结果表明:成功合成了HRH自聚物(PolyHRH)、以及共聚物[Poly(HRH-co-St)和Poly(HRH-co-MMA)].产物的热稳定性顺序为:HRH>PolyHRH>Poly(HRH-co-St)>Poly(HRH-co-MMA).     

大豆分离蛋白接枝氨基封端聚2-丙烯酰胺基-2-甲基丙磺酸的合成及溶液性质研究

用巯基乙胺为链转移剂,过硫酸铵为引发剂合成了氨基封端的聚2-丙烯酰胺基-2-甲基丙磺酸(H2N-PAMPS).再用1-(3-二甲氨基丙基)-3-乙基碳二亚胺盐酸盐(EDC)和N-羟基琥珀酰亚胺(NHS)在室温下催化H2N-PAMPS的端氨基与大豆分离蛋白(SPI)的羧基反应形成酰胺键,得到接枝物SPI-g-NH-PAMPS.用1H-NMR、傅利叶红外光谱、13C-NMR对H2N-PAMPS和接枝物SPI-g-NH-PAMPS进行结构表征.用zeta电位仪、紫外可见光光谱,荧光光谱,动态激光光散射对SPI及其接枝物SPI-g-NH-PAMPS的水溶液性质进行了研究.结果表明,与SPI相比,SPI-g-NH-PAMPS的溶解性、表面疏水性、乳化性等有所改善,接枝物SPI-g-NH-PAMPS聚集体粒径增大,形成独特的核壳结构.     

一种以聚酰亚胺为主链的分子刷合成及表征

以自制的侧基含溴的聚酰亚胺为大分子引发剂,2,2'-联吡啶/氯化亚铜为催化体系,通过原子转移自由基聚合(ATRP)反应,引发甲基丙烯酸三氟乙酯(TFEMA)和甲基丙烯酸2-(三甲基硅氧基)乙酯(HEMA-tms)共聚,制备了以聚酰亚胺为主链的分子刷,聚酰亚胺-接枝-聚(甲基丙烯酸三氟乙酯-共-甲基丙烯酸2-(三甲基硅氧基)乙酯),(PI-g-P(TFEMA-co-HEMA-tms)).对其中甲基丙烯酸2-(三甲基硅氧基)乙酯进行水解得到侧链含羟基的聚酰亚胺分子刷(PI-g-P(TFEMA-co-HEMA)),最后通过羟基与氯磷酸二乙酯反应,得到含亚磷酸酯基团的聚酰亚胺分子刷(PI-g-P(TFEMA-co-HEMA-P)).利用核磁共振氢谱(1H-NMR)、红外等方法,表征了所合成分子刷的结构.利用示差扫描量热法(DSC)、热失重分析(TGA)研究了聚合物分子刷的热性能.根据TGA计算出的分子刷组成与1H-NMR计算结果能较好的吻合.     

三元无规接枝共聚物的合成及其自组装性能的研究

通过甲基丙烯酸羟乙酯(HEMA)引发ε-己内酯(ε-CL)开环聚合得到带有双键的大分子预聚体甲基丙烯酸羟乙酯-聚己内酯(HEMA-PCL), 该预聚体与N-异丙基丙烯酰胺(NIPAAm)及丙烯酸(AAc)自由基聚合得到一系列含有不同比例组分的三元无规接枝共聚物. 研究了该聚合物的自组装性能. 通过1H NMR, FTIR, 凝胶渗透色谱(GPC)对聚合物进行结构和分子量的表征. 通过TEM, DLS与表面张力等方法表征其纳米粒子情况.     

硫代-iniferters法改性弹性蛋白的研究

弹性蛋白经对氯甲基苯甲酰氯氯化、二乙基二硫代氨基甲酸钠(NaSD)硫化制备了大分子iniferter剂(E-S), 再以E-S为引发剂, 在紫外光(UV)照射下引发甲基丙烯酸-β-羟乙酯(HEMA)聚合, 合成了聚甲基丙烯酸-β-羟乙酯(E-PHEMA)改性的弹性蛋白聚合物. 用红外(FTIR)和X射线光电子能谱(XPS)、热重分析(TGA)、扫描电镜(SEM)和动态接触角对改性弹性蛋白进行了表征. 结果表明: PHEMA键接到了弹性蛋白上; SEM显示改性后弹性蛋白的表面比未改性前变得光滑, 但改性后样品的热性能均低于未改性样品, 起始热分解温度由改性前的307.0 ℃变为260.2 ℃, 最大失重速率温度由347 ℃降到316.3 ℃; 动态接触角实验表明改性后样品具有良好的亲水性, 反应72 h后前进角由改性前的130.45°下降到35.40°, 接触角滞后由70.42°变为35.40°.     

聚甲基丙烯酸甲酯-聚甲基丙烯酸两亲性嵌段共聚物的制备及自组装形态的研究

以2-溴异丁酸乙酯为引发剂, 氯化亚铜/联二吡啶为催化剂, 通过原子转移自由基聚合(ATRP)获得分子链末端含一个α-溴原子的聚甲基丙烯酸甲酯(PMMA-Br), 以此为大分子引发剂引发甲基丙烯酸铅[Pb(MA)₂]单体进行ATRP反应, 制得P[MMA-b-Pb(MA)_2]嵌段共聚物, 将此共聚物在盐酸中进行离子交换即得聚甲基丙烯酸甲酯-聚甲基丙烯酸的两亲性嵌段共聚物[P(MMA-b-MAA)]. 用FTIR, GPC, NMR和SEM方法对共聚物进行了表征.     

活性正离子聚合与原子转移自由基聚合转换合成聚β-蒎烯接枝共聚物

通过活性正离子聚合与原子转移自由基聚合(ATRP)转换合成了β-蒎烯与甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)、苯乙烯(St)的新型接枝共聚物.首先以α-氯代乙苯/TiCl4/Ti(OiPr)4/nBu4NCl体系引发β-蒎烯活性正离子聚合,合成预定分子量大小和窄分子量分布的聚β-蒎烯,然后经N-溴代琥珀酰亚胺(NBS)定量溴化,得到溴化聚β-蒎烯大分子引发剂(Br/β-蒎烯链节摩尔比为0.5).然后将该大分子引发剂与溴化亚铜(CuBr)/2,2′-联吡啶(bpy)复合,引发MMA、BA、St进行ATRP接枝聚合.接枝反应显示一级动力学特征,且产物的分子量及分子量分布可控,表明上述ATRP接枝聚合反应具有可控聚合特征.接枝产物的结构经1H-NMR分析得到进一步证实.     

SYNTHESIS OF POLY(METHYL METHACRYLATE)-graft-POLYSTYRENE BY ATOM TRANSFER RADICAL POLYMERIZATION

The radical copolymerization of methyl methacrylate and 2-hydroxyethyl methacrylate was carried out via atomtransfer radical polymerization (ATRP) initiated by ethyl 2-bromoisobutyrate and catalyzed by CuBr/2,2'-bipyridinecomplex. This polymerization proceeds in a living fashion with controlled molecular weight and low polydispersity. Theobtained copolymer was esterified with 2-bromoisobutylryl bromide yielding a macroinitiator, poly(methyl methacrylate-co-2-hydroxyethyl methacrylate-co-2-(2-bromoisobutyryloxy)ethyl methacrylate), and its structure was characterized by ~1H-NMR. This macroinitiator was used for ATRP of styrene to synthesize poly(methyl methacrylate)-graft-polystyrene. Themolecular weight of graft copolymer increased with the monomer conversion, and the polydispersity remained relatively low.The individual grafted polystyrene chains were cleaved from the macroinitiator backbone by hydrolysis and the hydrolyzed product was characterized by ~1H-NMR and GPC.     

机理转移法合成聚丁二烯-b-聚(甲基丙烯酸N,N-二甲氨基乙酯)两亲性嵌段共聚物

将活性负离子聚合与原子转移自由基聚合(ATRP)技术相结合,运用机理转移法制备了一种两亲性材料聚丁二烯-b-聚(甲基丙烯酸N,N-二甲氨基乙酯)(PB-b-PDMAEMA)嵌段共聚物.首先通过负离子聚合方法设计合成聚丁二烯,用环氧丙烷封端,2-溴异丁酰溴作酯化剂,合成具有活性端基溴的聚丁二烯大分子引发剂(PB-B r),再用其引发亲水性单体DMAEMA进行原子转移自由基聚合,聚合动力学证实了该聚合反应具有典型的活性/可控自由基聚合的特征.通过差示扫描量热法(DSC)研究嵌段共聚物的微相分离行为.制备的大分子引发剂及两亲性嵌段共聚物经凝胶色谱、红外和核磁表征证实了预定的结构.     

Biomimetic anchors for antifouling and antibacterial polymer brushes on stainless steel

Barnacle cement (BC) was beneficially applied on stainless steel (SS) to serve as the initiator anchor for surface-initiated polymerization. The amine and hydroxyl moieties of barnacle cement reacted with 2-bromoisobutyryl bromide to provide the alkyl halide initiator for the surface-initiated atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate (HEMA). The hydroxyl groups of HEMA polymer (PHEMA) were then converted to carboxyl groups for coupling of chitosan (CS) to impart the SS surface with both antifouling and antibacterial properties. The surface-functionalized SS reduced bovine serum albumin adsorption, bacterial adhesion, and exhibited antibacterial efficacy against Escherichia coli (E. coli). The effectiveness of barnacle cement as an initiator anchor was compared to that of dopamine, a marine mussel inspired biomimetic anchor previously used in surface-initiated polymerization. The results indicate that the barnacle cement is a stable and effective anchor for functional surface coatings and polymer brushes.     

Graft polymerization of 2-hydroxyethyl methacrylate via ATRP with poly(acrylonitrile-co-p-chloromethyl styrene) as a macroinitiator

Amphiphilic graft copolymers are excellent additives for the development of antifouling membranes by nonsolvent induced phase separation. We report a convenient approach to the synthesis of novel graft copolymers with hydrophobic polyacrylonitrile (PAN) backbones and hydrophilic poly(2-hydroxyethyl methacrylate) (PHEMA) side chains. Atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate was carried out with poly(acrylonitrile-co-p-chloromethyl styrene) (PAN-co-PCMS) as a macroinitiator in the presence of CuCl/2,2’-bipyridine at 50 °C in dimethyl sulfoxide. Kinetics of the graft polymerization was also evaluated. The synthesis of poly(acrylonitrile-co-p-chloromethyl styrene-g-2-hydroxyethyl methacrylate) (PAN-co-(PCMS-g-PHEMA)) can be relatively controlled when CMS (the ATRP sites) unit in the macroinitiator is around 5 mol%. Both the macroinitiators and graft copolymers were characterized by FTIR, NMR and GPC. The surface morphology and wettability of the copolymer films were studied by AFM and water contact angle measurement, respectively. We demonstrate that phase segregation between the PAN-co-PCMS backbones and the PHEMA side chains takes place and the surface hydrophilicity of the graft copolymers increases with the length of the PHEMA side chains. Because these amphiphilic graft copolymers can be synthesized in mass, they will be useful as latent additives for the fabrication of advanced PAN separation membranes.     

星型两亲性聚己内酯-b-聚甲基丙烯酸(2-羟乙酯)嵌段共聚物的合成和表征

通过开环聚合(ROP)和原子转移自由基聚合(ATRP)制备了一类新型的两亲性嵌段共聚物——六臂星形聚(ε-已内酯)-b-聚甲基丙烯酸(2-羟乙酯)(6sPCL-b-PHEMA).6sPCL-b-PHEMA通过三步反应合成:(1)双季戊四醇开环聚合ε-己内酯的合成6sPCL;(2)以2-溴异丁基酰溴封端星形聚合物制备大分...     

Functionalization of three‐dimensionally ordered macroporous cross‐linked polystyrene by atom‐transfer radical polymerization of hydroxyethyl methacrylate and subsequent derivatization

The surface‐initiated atom‐transfer radical polymerization (ATRP) technique was applied to the graft polymerization of 2‐hydroxyethyl methacrylate (HEMA) from three‐dimensionally ordered macroporous crosslinked polystyrene (3DOM CLPS) on which the initiator (benzyl chloride) was immobilized onto the pore wall of 3DOM CLPS by chloromethylation of benzene ring. By the adjustment of the monomer concentration or graft polymerization time, the thickness of grafted polymer layers can be controlled. FTIR analysis confirms that the graft polymerization of HEMA via ATRP had been taken place at the pore wall of 3DOM CLPS. SEM images of PHEMA‐grafted 3DOM CLPS show that the ordered structure is well preserved after graft polymerization and the grafted layers are dense and homogeneous. The maximum thickness of grafted layer is up to 35 nm and the corresponding percent weight increase is 102.8% in this study. Moreover, the PHEMA layers were further functionalized in high yield via their reactive hydroxyl groups under gentle condition. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7950–7959, 2008     

Controlled grafting of acetylated starch by atom transfer radical polymerization of MMA

Graft copolymers of acetylated starch oligomer (AS) and poly(methyl methacrylate) (PMMA) were polymerized by atom transfer radical polymerization (ATRP). AS was converted to an ATRP macroinitiator by converting a part of the hydroxyl groups of AS to 2-bromoisobutyryl groups. Macroinitiators with varying degrees of substitution for the 2-bromoisobutyryl group were prepared. The polymerizations were conducted using CuBr/BiPy catalyst system, either in bulk or in 1:1 v/v THF solution. They proceeded with first-order kinetics and the molecular weights of the polymers increased linearly with conversion. Graft copolymers with different graft densities and graft lengths were prepared in a controlled manner. The hydrophobicity of these copolymers was studied by contact angle measurements.     

Layer-by-layer deposition of polyelectrolyte macroinitiators for enhanced initiator density in surface-initiated ATRP

The layer-by-layer (L-b-L) deposition of oppositely charged polyelectrolytic macroinitiators has been demonstrated on planar silica substrates. The build-up of the macroinitiator multilayers was monitored by ellipsometry (up to 21 layers) and dual polarization interferometry (up to 17 layers) and good agreement was found between these techniques. The increase in L-b-L thickness was approximately linear, with an average thickness of 2.3 A per layer of deposited macroinitiator. Surface-initiated ATRP of a model nonionic methacrylic monomer, 2-hydroxyethyl methacrylate (HEMA) in a 1:1 methanol/water mixture was conducted at ambient temperature. Increasing the number of macroinitiator layers led to a significant increase in PHEMA brush thickness up to 110 nm, which is attributed to the greater surface grafting density. PHEMA brush thicknesses obtained after 22 h showed a linear dependence on the number of layers of deposited macro-initiator, with all layers exhibiting near-identical growth kinetics. X-ray photoelectron spectroscopy was used to monitor L-b-L assembly and also to confirm PHEMA growth. This technique indicated the loss of small counterions from the multilayers during L-b-L deposition and confirmed an increase in the surface density of bromoester initiator groups as the number of deposited macroinitiator layers was increased. For 17 macroinitiator layers, the bromoester initiator density is estimated to be approximately 4.9 +/- 0.2 nm (-2) from the DPI data. This is comparable to that calculated for ATRP initiator monolayers obtained by either thiol or silane chemistry. Ellipsometry suggested that the macroinitiator multilayers were weakly hydrated prior to the in situ HEMA polymerization. AFM studies indicated that the PHEMA brushes had appreciable surface roughness, but this roughness became negligible compared to the brush thickness with increasing macroinitiator layers.     

Drug release property of a pH-responsive double-hydrophilic hyperbranched graft copolymer

In this paper, we report the synthesis and self-assembly of double-hydrophilic hyperbranched graft copolymers of HPG-g-PDMAEMA, which consist of a hyperbranched polyglycerol (HPG) core and several grafted poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) arms. HPG was synthesized by cationic polymerization. Then HPG-Br macroinitiator was obtained by esterification of HPG with 2-bromoisobutyryl bromide, which was subsequently used in the preparation of HPG-g-PDMAEMA graft copolymers through atom transfer r...