ARGET ATRP 与ROP 结合制备pH 响应两亲性聚合物分子刷及其自组装研究

结合电子转移活化剂再生-原子转移自由基聚合(ARGET ATRP)和开环聚合(ROP)法合成了一种具有无规疏水/ pH 响应结构的两亲性聚合物分子刷聚(甲基丙烯酸聚丙交酯酯-co-甲基丙烯酸)-b-聚甲基丙烯酸单甲氧基聚乙二醇酯 [P(PLAMA-co-MAA)-b-PPEGMA]. 通过核磁共振氢谱(¹H NMR)和凝胶渗透色谱(GPC)表征了聚合物的结构、分子量及分子量分布. 优化了反应条件并合成出分子量可控、分子量分布窄的聚合产物. 采用动态光散射法(DLS)、扫描电子显微镜(SEM)研究了聚合物分子刷在水溶液中自组装胶束的粒径、形貌及pH 响应行为. P(PLAMA-co-MAA)-b-PPEGMA 自组装形成粒径分布均匀的球形胶束. 且随着溶液pH 值从7 降低至3, 胶束中的PMAA 逐渐去离子化, 溶胀的胶束逐渐收缩, 粒径由200～300 nm 减小至150 nm 左右; 但当pH 值减小到2 以下, 胶束表面电荷量非常小, 胶束聚集, 使得粒径增大.

Synthesis of pH-Sensitive Amphiphilic Copolymer Brush by the Combination of ARGET ATRP with ROP and Its Self-Assembly Behavior

A random hydrophobic/pH-sensitive copolymer brush poly(polylactide methacrylate-co-methacrylic acid)-b-poly(poly(ethylene glycol) methyl ether methacrylate) [P(PLAMA-co-MAA)-b-PPEGMA] was synthesized by the combination of activators regenerated by electron transfer atom transfer radical polymerization(ARGET ATRP) with ring opening polymerization(ROP).The chemical structure,molecular weight and polydispersity index were characterized by nuclear magnetic resonance hydrogen spectrum(1H NMR) and gel permeation chromatography(GPC).The reaction conditions of polymerization were optimized and polymer products with controllable molecular weight and narrow distribution were ob-tained.The self-assembly behavior(micelle size,morphology and pH-sensitive properties) of the polymer brush was investigated by dynamic light scattering(DLS) and scanning electron microscopy(SEM).The P(PLAMA-co-MAA)-b-PPEGMA self-assembled micelles were sphere in morphology and with an uniform particle size.As the solution pH decreased from 7 to 3,the deionization of carboxyl groups of PMAA con-tributed to the shrinking of micelle structure,which made the micelle size decreased from 200～300 nm to about 150 nm.When the solution pH decreased to below 2,the surface charge of micelle became very small which resulting in the aggregation of micelles and the increase of micelle size.