阴离子聚合的分子量分布的动力学分析

Molecular Weight Distribution of Ionic Polymerization

用一种非常简单的基于矩法的方法,对理想机理、慢引发和逐步终止3种动力学情况的阴离子聚合反应的分子量分布进行了分析。分析表明:理想机理的平均链长受反应时间控制,而不受化学控制,高分子产物的多分散指数(PDI)接近于1。引发速率对PDI影响不大。而若存在逐步终止反应时,单体的完全转化是获得窄分布高分子量聚合物的必要条件。

Using a particular simple approach based on the method of moments, the molecular weight distribution of ionic polymerization was derived. In the ideal kinetic ease, the average chain length is limited by the reaction time rather than stoichiometry. In the slow initiation case, the initiation rate has very little effect on the polydispersity of high polymers unless it becomes slower than propagation. In the gradual termination case, low polydispersity generally requires nearly complete conversion of the monomer. When achievement of the limiting chain length coincides with essentially complete conversion of the monomer, the polydispersity can be low.