几种烯丙基硫类不可逆加成断裂链转移剂在苯乙烯乳液聚合中的应用

Study on emulsion polymerization of styrene in the presence of allyl sulfur based on irreversible addition-fragmentation chain transfer agent

合成了4种烯丙基硫类不可逆加成断裂链转移剂,研究了4种链转移剂在苯乙烯乳液聚合中的应用,考察了4种链转移剂对乳液聚合速率、乳胶粒子大小的影响以及对聚合物相对分子质量的调控规律。正辛基-2-苯基烯丙基硫加入体系后出现浮油现象,难以有效调节聚苯乙烯的相对分子质量;异辛基-2-苯基烯丙基硫对聚合速率影响很小,对相对分子质量有一定的调控效果;正戊基(2)-2-苯基烯丙基硫和叔丁基-2-苯基烯丙基硫对聚苯乙烯相对分子质量的调控效率高于异辛基-2-苯基烯丙基硫,但聚合速率均有一定程度的下降,在整个聚合过程中正戊基(2)-2-苯基烯丙基硫和叔丁基-2-苯基烯丙基硫体系中聚苯乙烯的相对分子质量几乎保持不变,且改变其用量,可有效调节聚合物的相对分子质量。

Four chain transfer agents based on irreversible addition-fragmentation chain transfer mechanism,octyl(2-phenylallyl)sulfur,(2-ethylhexyl)(2-phenylallyl)sulfur,pentanyl(2)-2-phenylallyl)sulfur,tert-butyl(2-phenylallyl)sulfur,were synthesized.The emulsion polymerizations of styrene in the presence of these agents were carried out.The influences of these agents on the rate of polymerization,the diameter of latex particles and the number-average molecular weight of polystyrene were investigated.It was found that octyl(2-phenylallyl)sulfur cannot control the polystyrene molecular weight regularly because of super-swelling effect;(2-Ethylhexyl)(2-phenylallyl)sulfur has a slight effect on the polymerization rate and can control the molecular weight,pentanyl(2)-2-phenylallyl)sulfur and tert-butyl(2-phenylallyl)sulfur are more efficient than(2-ethylhexyl)(2-phenyla-llyl)sulfur on regulating the polystyrene molecular weight,but the polymerization rates have decreased obviously.These two agents could keep the polystyrene molecular weight constant during the whole polymerization process and regulate the molecular weight effectively by adjusting the amount of these two agents.