高分子化学反应中几率效应的计算机模拟

Computer Modeling of Probability Effect in the Chemical Reactions of Polymers

几率效应是影响高分子反应的一个重要因素,聚氯乙烯(PVC)与锌粉共热脱氯成环的反应是一受几率效应影响的典型例子。在假设分子链上任意一对相邻的未反应基团发生反应的概率相等的情况下,Flory利用递归法对该反应的最大反应程度进行了理论推导,得到的结果为86.47%(即1-e-2)。本文从另一种概率模型出发,即每个未反应基团和与其相邻两侧的未反应基团发生反应的概率相同,利用计算机编程模拟了单根聚氯乙烯分子链脱氯反应的过程,得到该反应平均最大反应程度为86.06%。同时,由于程序的指令可以与分子链中的自由旋转单元的内旋转相关联,我们进而对该反应的过程进行了推测和探讨,并得到了与实验结果吻合的反应动力学曲线。

Probability effect is one of the most important factors that influence the chemical reactions of polymers. A case in point is the dechlorination of polyvinyl chloride （PVC）when heated with zinc. Under the assumption that the probability of reaction of each adjacent pair of unreacted substituents is the same, Flory predicted that the theoretic value of the maximum extent of this reaction was 86.47% （or I --e-z ） via recursion method. In this article, under a different assumption that each unreacted substituent reacts with its adjacent substituent on either side with equal possibility, the reaction of one polymer chain was modeled by computer programming. The result indicated that the maximum extent of this reaction was 86.06 %. In the meanwhile, taking advantage of the fact that the instructions in the program were related to the intramolecular rotation of each freely rotating unit in the polymer chain, the procedure of this reaction was predicted and discussed and the kinetic plot which was in agreement with experiment result was obtained.