水分散体系中由BPO或KPS引发的苯乙烯反向原子转移自由基聚合

分别以过氧化二苯甲酰 (BPO)和过硫酸钾 (KPS)为引发剂、1 ,1 0 邻二氮菲为催化剂配体、十二烷基磺酸钠为乳化剂 ,在水分散体系中进行了苯乙烯的反向原子转移自由基聚合反应 .结果表明 ,对于BPO引发的苯乙烯乳液聚合反应 ,必须由CuBr和CuBr2 形成复合催化剂体系才能达到较好的控制效果 ,其中CuBr可以是直接加入到催化剂体系中 ,也可以是由CuBr2 与Cu0 就地快速反应生成 .CuBr迅速地与BPO反应而实现活性聚合中所谓的“快引发” ,从而有效地控制苯乙烯的聚合反应 .对于KPS引发的苯乙烯乳液聚合体系 ,反应介质的pH值对聚合有很大的影响 ,反应速度随着反应介质pH值的升高而加快 .实验结果表明 ,由两种不同引发剂引发的苯乙烯的乳液的粒径及粒径分布也有很大的差异

REVERSE ATOM TRANSFER RADICAL EMULSION POLYMERIZATION OF STYRENE INITIATED BY BPO OR KPS

Reverse atom transfer radical polymerization of styrene initiated by benzoyl peroxide(BPO) or potassium persulfate(KPS) in emulsion systems with phenanthroline as ligand and sodium lauryl sulfate as surfactant was studied.For the BPO initiator system,the good control over the polymerization of styrene was observed when both CuBr and CuBr 2 were simultaneously introduced into the reaction system.In this case,the fast initiation could be expected as a result of the quick redox reaction of CuBr and BPO,and the addition of CuBr 2 at the beginning of polymerization could further improve the controllability of the polymerization.For the polymerization initiated by KPS,the pH value of the reaction medium played a crucial role in affecting the polymerization rate of St which increased with the increase of the pH value of the medium.The particle size and particle size distribution of the synthesized polystyrene with BPO or KPS were measured,and found to be quite different.