Kinetic study of the step-growth polymerization of hydroxyl-terminated poly(dimethylsiloxane) (PDMS) and triisocyanate has been done in this work. Kinetic Monte Carlo simulations are performed to understand the experimental investigation of the cross-linked network formation. This approach enables us to afford a visualization of the entire network formation in detail and evaluate its characteristic properties. A comparison between the current simulation results and that from classical theories (e.g., Flory and Macosko–Miller theoretical calculations) is done. In addition, the Cole–Poehlein diffusion model based on the free volume theory, involving a parallel summation of the chemical and diffusional rate coefficients, is used to describe the effect of diffusion-controlled mechanism on polymerization. Moreover, the effect of experimental conditions, such as the ratio of [NCO]/[OH] and the molar mass of PDMS, on network formation kinetics is also investigated. The simulation results demonstrate that the [NCO]/[OH] ratios within the range of 1–1.2 and PDMS with lower molar mass are preferred to prepare a polymer network with a high cross-linking density. It is believed that the current kinetic modeling provides a way for better understanding the kinetics and optimizing the experimental conditions.

中文翻译：

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基于逐步增长聚合的聚二甲基硅氧烷的网络形成动力学

在这项工作中已经完成了羟基封端的聚（二甲基硅氧烷）（PDMS）和三异氰酸酯的逐步增长聚合的动力学研究。进行动力学蒙特卡罗模拟以了解交联网络形成的实验研究。这种方法使我们能够详细地可视化整个网络的形成并评估其特征属性。对当前模拟结果与经典理论（例如 Flory 和 Macosko-Miller 理论计算）的结果进行了比较。此外，基于自由体积理论的 Cole-Poehlein 扩散模型，涉及化学和扩散速率系数的并行求和，用于描述扩散控制机制对聚合的影响。此外，受实验条件的影响，例如 [NCO]/[OH] 的比率和 PDMS 的摩尔质量，对网络形成动力学也进行了研究。模拟结果表明，[NCO]/[OH] 比率在 1-1.2 范围内和较低摩尔质量的 PDMS 更适合制备具有高交联密度的聚合物网络。相信目前的动力学模型为更好地理解动力学和优化实验条件提供了一种方法。