甲基苯乙烯的无乳化剂乳液聚合机理研究

Mechanism of Emulsifier-free Emulsion Polymerization of Methylstyene

采用电导法、紫外光谱法、GPC和电子显微镜等方法对甲基苯乙烯和苯乙烯的无乳化剂乳液聚合进行了较为详细的研究。探讨了这两种单体在无乳化剂乳液聚合初期的引发成核机理 ,比较了它们在无乳化剂乳液聚合时的异同。甲基苯乙烯的无乳化剂聚合机理与苯乙烯类似 ,即采用胶束成核机理聚合。但是 ,由于甲基苯乙烯有较低的活化能和链增长速率常数 ,使其在聚合初期有较高的转化率和更加显著的水相终止。所以在相同的条件下 ,甲基苯乙烯比苯乙烯有较大的胶乳粒子尺寸。

The mechanism of emulsifier free emulsion polymerization of methylstyrene and styrene was studied. It was found that the polymerization mechanism of methylstyrene is similar to that of styrene and both of them were the micellization nucleation mechanism . In the early stage of polymerization, however, a much difference between polymerization behavior of styrene and methylstyrene was observed. The dialysis and conversion study of the emulsions in the early stage of polymerization revealed that methylstyrene has a higher initiation rate and lower propagation rate than styrene. This remarkable difference may be due to the presence of methyl group in methylstyrene. Finally highly monodisperse latex particles of poly(methylstyrene) can be obtained by the emulsifier free emulsion polymerization.