脉冲激光引发自由基聚合的动力学研究

A Study of the Kinetics of Pulsed Laser initiated Radical Polymerization

处理了无链转移时脉冲激光引发自由基聚合中的动力学问题：推导出聚合产物数均和重均分子量的严格数学表达式，给出了链自由基、死聚物及总的聚合产物的归一化的分子量分布函数．计算结果表明：随着单体转化率的上升，各种分子参数，例如数均和重均分子量，以及多分散指数的数值周期性地振荡，且振幅逐渐下降．分子量分布曲线则包含一些特征峰，且随着每次脉冲激光产生的初级自由基浓度的降低，分布曲线峰的数目增加．另外，与歧化终止相比，偶合终止使产物的分子量分布略为变窄．

This paper dealt with the kinetics of radical polymerization initiated by pulsed laser in the absence of chain transfer reaction. The rigorous expressions of the number and weight average degrees of polymerization for resulting polymer were derived. In the meantime, the normalized molecular weight distribution functions for chain radicals, terminated species and total polymer were obtained respectively. Numerical calculation shows that the values of various molecular parameters, such as number and weight average molecular weights and polydispersity index, periodically vibrate between maxima and minima, and the amplitude of vibration decreases with increasing monomer conversion. The molecular weight distribution curves consist of some characteristic peaks, and the number of peaks increases with the decreasing of concentration of the primary radicals formed at the beginning per laser pulse. Comparing with disproportionation termination, combination termination leads to a narrower molecular weight distribution of resultant polymer.