乳液体系下聚合诱导自组装行为研究

This project is focused on the investigation of polymerization induced self-assemble behavior in emulsion RAFT polymerization. To accomplish our goal, trithiocarbonate-containing amphiphilic brush copolymers with controlled side chains are firstly synthesized via grafting-from strategy through the combination of RAFT and ATRP techniques. Subsequently, the synthesized amphiphilic brush copolymers are used as both the Macro-RAFT agent and surfactant in the emulsion polymerization of styrene or acrylate. The effects such as the special molecular structure of brush copolymer against linear polymer, the steric hindrance between brush copolymer side chains, the length and chemical component of side chains in brush copolymer as well as the emulsion polymerization monomer, on the emulsion RAFT polymerization behavior and the morphology of the synthesized block copolymer colloid will be explored. The rules of polymerization induced self-assemble behavior in emulsion RAFT polymerization will be summarized by checking the size and number evolutions of the polymer colloid during the emulsion RAFT polymerization and speculating the determination of the interfacial tension between the core and the solvent, the degree of stretching of the core-forming blocks and the interaction among the corona chains on the polymer colloid morphology. . This project is anticipated to offer a potential theoretical guidance for the preparation of the concentrated, stable, surface property and morphology tunable block copolymer colloids by emulsion polymerization.

通过研究刷形乳化剂调介下的乳液RAFT聚合，揭示乳液体系下聚合诱导自组装行为规律是本项目的研究目标。为此，拟采用grafting-from方法，结合RAFT与ATRP技术，合成含三硫代碳酸酯基团侧链化学组成可调控的两亲性刷形聚合物。以合成的刷形聚合物为大分子RAFT试剂和乳化剂，研究苯乙烯或丙烯酸酯类单体的乳液RAFT聚合。讨论刷形聚合物分子结构、侧链长度、空间位阻、化学组成及乳液聚合单体的种类对于乳液RAFT聚合行为以及合成的嵌段共聚物胶体形态的影响。系统总结，乳液RAFT聚合中，嵌段共聚物胶体尺寸以及数目的变化规律，嵌段共聚物胶体中成核链段在核中的伸缩性、胶束核与溶剂之间的表面张力以及壳层链段间的相互排斥力对嵌段共聚物胶体形态的影响，揭示刷形乳化剂调介乳液RAFT聚合诱导自组装行为规律。为乳液聚合方法制备高浓度、稳定性好、表面性质可调节以及形态可控的嵌段共聚物胶体提供理论基础。

乳液聚合是批量制备聚合物胶体的有效方法。通过乳液聚合制备形态可控聚合物胶体一直是一项挑战。本项目通过设计合成多种末端含有三硫代碳酸酯基团的两亲性大分子乳化剂（Macro-RAFT），包括线型、Y型和刷型，分别研究它们调介下的苯乙烯或丙烯酸酯类单体的乳液RAFT聚合。聚合导致体系中原位生成嵌段共聚物胶体，通过研究聚合动力学以及嵌段聚合物胶体形态变化，揭示乳液体系下的聚合诱导自组装行为规律。研究表明：1）通过优化聚合条件，Macro-RAFT调介下的乳液RAFT聚合均具有良好的聚合可控性，嵌段共聚物分子量随单体转化率线性增大，符合假一级动力学过程；2）线型和Y型Macro-RAFT调介下的乳液RAFT聚合通常只能得到球形嵌段共聚物胶体，随粒子尺寸随聚合度增大，链段比例对形态影响不显著；3）刷型Macro-RAFT调介下的乳液RAFT聚合能够制备出多种形态的聚合物胶体，且聚合物胶体的形态主要受聚合度控制，随聚合度增大聚合物胶体形态的演变规律为小尺寸球形-蠕虫状-囊泡状-大尺寸球形。该方法有望为乳液RAFT聚合方法批量制备形态可控聚合物胶体提供理论支持。