Tsimouri Ioanna Ch, Schwarz Fabian, Bernhard Tim, Gusev Andrei A
Department of Materials, ETH Zürich, CH-8093 Zürich, Switzerland.
Macromolecules. 2024 Apr 17;57(9):4273-4284. doi: 10.1021/acs.macromol.3c02544. eCollection 2024 May 14.
Long-standing experimental data on the elastic modulus of end-linked poly(dimethylsiloxane) (PDMS) networks are employed to corroborate the validity of the Miller-Macosko theory (MMT). The validity of MMT is also confirmed by molecular dynamics (MD) simulations that mimic the experimentally realized networks. It becomes apparent that for a network formed from bulk, where the fractions of the loops are small, it is sufficient to account for the topological details of a reference tree-like network, i.e., for its degree of completion, junction functionalities, and trapped entanglements, in order to practically predict the modulus. However, a mismatch is identified between the MMT and MD simulations in relating the fraction of the soluble material to the extent of reaction. A large contribution of entanglements to the modulus of PDMS networks prepared with short precursor chains is presented, suggesting that the elastic modulus of commonly used end-linked PDMS networks is in fact entanglement-dominated.
长期以来关于端基连接的聚二甲基硅氧烷（PDMS）网络弹性模量的实验数据被用于证实米勒 - 马科斯柯理论（MMT）的有效性。MMT的有效性也通过模拟实验实现的网络的分子动力学（MD）模拟得到了证实。很明显，对于由本体形成的网络，其中环的比例较小，为了实际预测模量，考虑参考树状网络的拓扑细节，即其完成度、连接功能和被困缠结就足够了。然而，在将可溶材料的比例与反应程度相关联方面，MMT和MD模拟之间存在不匹配。研究表明缠结对用短前驱体链制备的PDMS网络的模量有很大贡献，这表明常用的端基连接的PDMS网络的弹性模量实际上是以缠结为主导的。
