pH和温度诱导双亲水嵌段共聚物聚甲基丙烯酸-b-聚N-(2-甲基丙烯酰氧乙基)吡咯烷酮水溶液的胶束化

基于可逆加成裂解链转移自由基(RAFT)聚合法开发了一系列新型双亲水嵌段共聚物——聚甲基丙烯酸-b-聚N-(2-甲基丙烯酰氧乙基)吡咯烷酮(PMAA-b-PNMP)，并利用凝胶渗透色谱法(GPC)和¹H NMR对其结构进行了表征。光散射和冷冻电镜的结果表明，此类双亲水嵌段共聚物的水溶液具有pH和温度诱导胶束化的现象，而且PNMP的聚合度对胶束化的pH和温度影响都非常大。一般而言，PNMP的聚合度越大，胶束化的pH值越小，胶束化的温度则越高。pD相关的¹H NMR结果表明，PNMP与PMAA片段和水分子之间氢键的削弱以及PNMP与PMAA链之间相互作用的增强是pH诱导PMAA-b-PNMP胶束形成的主要原因，而PNMP片段与水分子之间氢键的削弱则是温度诱导PMAA-b-PNMP胶束形成的主要原因。此外，我们发现在PMAA-b-PNMP体系中制备的纳米金颗粒的大小可通过溶液pH进行可控调节。总体而言，pH值越高，金纳米颗粒的粒径越小。

pH- and Temperature-Induced Micellization of the Dual Hydrophilic Block Copolymer Poly(methacrylate acid)-b-poly(N-(2-methacryloylxyethyl) pyrrolidone) in Aqueous Solution

Anew series of structurally controllable dual hydrophilic diblock copolymers poly(methacrylate acid)-b- poly(N-(2- methacryloylxyethyl) pyrrolidone), PMAA-b-PNMP including PMAA101-b-PNMP153, PMAA101-b- PNMP₂₄₀, PMAA101-b-PNMP₄₂₀, and PMAA₁₀₁-b-PNMP₅₃₉, were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization and characterized by gel permeation chromatography (GPC) and ¹H nuclear magnetic resonance (NMR). The pH- and temperature-induced micellization behavior of PMAA-b-PNMP in aqueous solution was confirmed by static light scattering (SLS) and dynamic light scattering (DLS) and cryogen transmission electron microscopy (cryo-TEM) techniques. The polymerization degree of PNMP strongly affects the micellization behavior. Generally, with higher polymerization degree, the micellization pH was lower and the micellization temperature was higher. During the micellization processes, the weakness of the hydrogen bond interactions between water and PNMP or PMAA and the strength in the inter- and intra-chain interactions between PNMP and PMAA segments are dominant during the pH-induced micellization, as revealed by the pDdependent ¹H NMR spectra. However, the weakness in the hydrogen bond interactions between water and PNMP is the major cause of the temperature-induced micellization process. We also provide solid evidence for the ability to control the size of Au NPs by adjusting the pH in the presence of PMAA-b-PNMP. Specifically, with higher pH, the size of the Au NPs was smaller.