温敏星形树枝化聚合物的制备及表征  

Preparation and Characterization of Thermoresponsive Star Dendronized Polymers

作　　者：李娟[1] 苏新艳[1] 李文[1] 刘坤[1] 张阿方[1] Juan Li Xin-yan Su Wen Li Kun Liu A-fang Zhang(College of Materials Science and Engineering, Shanghai University, Shanghai 20044)

机构地区：[1]上海大学材料科学与工程学院,上海200444

出　　处：《高分子学报》2017年第2期367-374,共8页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号21474060);上海市自然科学基金(基金号16ZR1411300)资助项目

摘　　要：通过两步可逆-加成断裂链转移(RAFT)聚合反应制备了双嵌段树枝化共聚物PPDSn-b-PG1m,以此嵌段共聚物为臂,进一步以1,2-乙二硫醇为交联剂通过二硫键与巯基的交换反应实现核交联,采用"先臂后核"法设计制备了系列以烷氧醚树枝化聚合物为臂的温敏星形树枝化聚合物PPDSn-b-PG1m-SS.采用1H-NMR、GPC对目标星形树枝化聚合物的结构和分子量进行了分析表征;利用变温UV-Vis光谱和原子力显微镜等分别考察了目标星形树枝化聚合物水溶液的温敏行为及其分子形貌特征.结果表明,该类星形树枝化聚合物具有与母体树枝化聚合物类似的优异温敏行为(相转变温度~36?C),其单分子尺寸较大,且随着臂长的不同在底物上分别呈现出明显的星状或球状形貌.A series of star dendronized polymers PPDSn-b-PG1m-SS, constituted by cross-linked disulfide core and oligoethylene glycol（OEG）-based dendronized polymer arms, were designed and synthesized by the ＂arm first＂ approach for the first time. Due to the large difference between molar masses of dendronized macromonomer and conventional monomers, diblock copolymers used for core crosslinking were prepared by using the monomer bearing pyridyldisulfide side groups to form the first block. Therefore, the macro chain transfer agents（PPDS） were obtained by reversible addition-fragmentation chain transfer（RAFT） polymerization of monomer bearing pyridyldisulfide side groups. These terminally reactive macro chain transfer agents were subsequently used to further initiate polymerization of OEG-based dendritic monomer（MG1）, affording well-defined diblock copolymers. Finally, the objective star dendronized polymers were prepared based on thiol-disulfide exchange reaction by adding 1,2-ethanedithiol as cross-linkers. The structure and molecular weights of the resulting polymers were characterized by ^1H-NMR and GPC. UV-Vis spectroscopy and AFM were used to investigate the thermoresponsive behaviors and morphologies of the polymers, respectively. The results showed that star dendronized polymers were successfully prepared. Similar to their linear dendronized counterparts, these star polymers showed fast and sharp phase transitions with small hysteresis. Ascribed to the dendronized topology, these star dendronized polymers were directly visualized by AFM on mica to have star or spherical morphologies, dependent mainly on the chain length of the dendronized polymer arms. Therefore, we provide here the first example for convenient synthesis of thermoresponsive star dendronized polymers through core cross-linking of diblock dendronized polymers, which provide a platform to investigate the topological effects on stimuli-responsiveness of dendronized polymers. Due to the dynamic characteristics of thiol-disulfide excha

关 键 词：温度敏感性 烷氧醚 树枝化聚合物 星形聚合物 

分 类 号：O631.5[理学—高分子化学]