单分散羧基化聚苯乙烯微球的辐射聚合制备及其应用研究

Monodisperse micrometer-size carboxyl-functionalized polystyrene particles obtained by radiation-induced polymerization and the research on its application

本工作采用辐射分散两步聚合法,以苯乙烯(St)为单体,衣康酸(IA)为共聚单体,聚乙烯吡咯烷酮(PVP)为稳定剂,乙醇/水混合溶剂为分散介质,合成了粒径0.6～2.1μm的单分散羧基化聚苯乙烯微球。在两步聚合法的第一步反应中成核阶段已经基本结束,成核粒子数目也已保持稳定。因此,在第二步反应中加入共聚单体会减少二次成核的机率,所得到的聚合物微球的单分散性较好,并与辐射分散聚合一步法作了对比。详细讨论了分散聚合过程中,稳定剂用量、乙醇/水质量比以及衣康酸含量对于聚合物微球的粒径及粒径分布的影响;用电导滴定法表征了羧基官能团在分散共聚合各相中的分配情况;以制得的羧基化聚苯乙烯微球为模板在辐射场中通过多次辐射界面还原反应得到P(St-co-IA)/Co复合微球。

Monodisperse carboxyl-functionalized synthesized by two-stage radiation-induced dispersion （vinylpyrrolidone） （PVP） as the stabilizer and itaconic polystyrene particles size with range of 0.6-2.1μm were polymerization of styrene in ethanol/water media using poly acid （IA） as a functional comonomer. The resulting carboxy-lated polystyrene （PS） particles have a narrower size distribution compared with those obtained by one-stage dispersion polymerization. In the two-stage method, the presence of additional IA in the second reaction stage may help to prevent secondary nucleation and to promote the formation of monodisperse particles. The effects of concentration of IA, PVP and solvent polarity on the particle size and size distribution have been discussed in detail. The carboxyl group density on the surface of the copolymer particles has been determined directly by conductometric titration. In order to examine the functionality of the particles, P（St-co-IA）/Co composite microspheres are prepared by repetitious interface reduction reactions.