D_4/APAEDMS本体开环共聚反应机理及调控基元反应

Controlling elementary reaction of bulk ring-opening copo lymerization of octamethylcyclotetrasiloxane with N-β-aminoethyl-γ-aminopropylmethyldimethyoxysilane

MonteCarlo方法首次用来揭示八甲基环四硅氧烷(D4)与N-β-氨乙基-γ-氨丙基甲基二甲氧基硅烷(APAEDMS)的本体开环共聚反应机理的关键调控基元反应.基于已提出的该体系本体共聚反应机理,并兼顾模拟精度与计算经济性,MonteCarlo模拟模型采用自由体积理论简化扩散效应并与本征反应动力学方程耦合.其中,本征动力学速率常数通过模拟主要共聚基元反应得到.基于优化的动力学速率常数通过模拟从分子水平上揭示:D4/APAEDMS本体共聚机理为一伴有逐步特征的阴离子连锁聚合.其中,链引发及其逆反应对D4/APAEDMS的本体共聚反应没有直接调控作用,而链缩合及其逆反应是本体系反应机理不同于纯活性阴离子聚合或逐步聚合反应机理的关键原因.

The bulk ring-opening copolymerization mechanism of octamethylcyclotetrasiloxane （D4 ） with N-β-aminoethyl-γ-aminopropylmethyldimethyoxysilane （APAEDMS） and its key controlling elementary reactions were firstly investigated and demonstrated by means of the Monte Carlo method in this paper. With consideration of the cost of computation as well as the precision of simulated results, a new computational model was developed to simulate the reaction system based on the free volume theory and the chemical reaction kinetic theory. The intrinsic reaction rate constants were obtained by simulating the main elementary reactions of copolymerization. This paper indicates from microscopic level： （1） The bulk copolymerization mechanism of D4 with APAEDMS is an anion chain-reaction mechanism with the characteristics of the step polymerization. （2） The chain-condensation reaction and its reversible reaction are the key controlling elementary reactions of the copolymerization mechanism for the studied system, while the chain initiation elementary reactions are not the key controlling elementary reactions of the copolymerization mechanism for the studied system.