对甲基苯乙烯阳离子聚合研究

采用PEC1／SnCl4/CH2Cl2/Bu4N^ Br^-/-15℃体系进行了对甲基苯乙烯阳离子聚合。分别研究了Bu4N^ Br^-浓度、溶剂极性和单体浓度等对聚合的影响。结果表明：对甲基苯乙烯聚合速度非常快，5min即能完成反应；溶剂极性对聚合速度影响较大，溶剂极性降低，反应速度减慢。在 纯的非极性溶剂中，聚合物为多峰分布；在纯CH2Cl2中，Bu4N^ Br^-用量从0.005mol/L到0.05mol/L对对甲基苯乙烯的聚合无影响。在极性较低的体系中，Bu4N^ Br^-对聚合影响很明显，聚合速度显著降低，相对分子质量分布交窄；在本聚合体系中都存在着一定程度向单体的链转移，不是活性聚合。

THE CATIONIC POLYMERIZATION OF p-METHYLSTYRENE

The polymerization of p-methylstyrene was investigated in the PECl/SnCl 4/CH 2Cl 2/Bu 4N +Br - system. It is found that the polymerization of p-methylstyrene is much faster than styrene, but in the mixture diluent of CH 2Cl 2 and cyclohexane, the polymerization rate slow down. In the pure CH 2Cl 2, the concentration of Bu 4N +Br - has no effect on polymerization at the range of 0.005 mol/L to 0.05 mol/L of Bu 4N +Br -, however in lower polarity diluent, such as the mixture diluent of CH 2Cl 2 and cyclohexane, Bu 4N +Br - plays a important role in the polymerization and can slower the polymerization rate and can make the MWDs narrow. The relationship of the MW and monomer concentration indicated there are some transfer to monomer in the system.