Living Free Radical Microemulsion Polymerization of Methyl Methacrylate

[中文文摘]采用双硫酯存在下的活性自由基聚合方法进行了甲基丙烯酸甲酯的活性自由基微乳液聚合研究 .比较了三种乳化剂对聚合体系稳定性和分子量控制的影响 .在单体含量约 8%时 ,以阳离子型乳化剂十六烷基三甲基溴铵(CTAB)为乳化剂可以得到稳定的微乳液 ,且具有明显的活性聚合特征 ,即产物分子量随转化率的增加而增大 ,实测分子量和理论分子量相近 ,分子量多分散性系数小于 1.3.产物的分子量控制在 4万以下时达到较高的精度 .聚合过程存在明显的聚合恒速期 .而用阴离子型乳化剂十二烷基硫酸钠 (SDS)和非离子型乳化剂OP 10则需加入长链醇类助乳化剂 .助乳化剂虽可提高微乳液的稳定性和单体含量 ,但不利于微乳液分子量的控制 .反应温度对产物分子量及分子量分布的控制和体系的稳定没有明显影响 .胶乳直径小于 30nm ,略大于未加链转移剂的正常微乳液聚合胶乳 .产物的立体规整度较高 ,间规PMMA占59%.[英文文摘]The microemulsion polymerization of MMA were carried out by using three different surfactants by adding the chain transfer agent 1-phenylethyl dithiobenzoate (PhC(S)SCH(CH 3)Ph). It was found the microemulsion polymerization of MMA had the characteristic of living radical polymerization without the co-surfactant. The polymers had molecular weight that were close to those predicted by the ratio of consumed monomer to added chain transfer agent, and they also displayed narrow molecular weight distribution (Mw PMn < 1. 3) . The co2surfactants could improve the stability of the microemulsion throughout the polymerization , but they were the poisons of living radical polymerization at high conversion; the polydispersites turned wider , the real molecular weight are larger than the theoretical molecular weight greatly. The microemulsion polymerization of MMA was carried out under different temperature by using the ternary system water PCTABPMMA. The results showed the temperature did not affect the stability of the microemulsion , but the polymerization rate increased as the temperature increased. The TEMwas used to study the size of these latex particles , and the diame2 ter of these latex particles was about 20～30 nm. The syndiotacticity of PMMA synthesized by microemulsion polymerization with chain transfer agent was higher than that of normal microemulsion polymerization.固体表面物理化学国家重点实验室基金(1130