Wu Chaofu
Hunan Provincial Key Laboratory of Fine Ceramics and Powder Materials, School of Materials and Environmental Engineering, Hunan University of Humanities, Science and Technology, Loudi, Hunan, 417000, People's Republic of China.
J Mol Model. 2022 Jul 8;28(8):214. doi: 10.1007/s00894-022-05214-8.
Multiscale coarse-grained (CG) models are expected to play the critical roles in molecular simulations of complex polymers. However, this poses a great challenge for accurately simulating their thermomechanical properties, for which excellent representability and transferability are required for the CG potentials. In this work, virtual sites and elastic network bonds are introduced to improve the structural and volumetric property-based CG models including explicit electrostatic interactions, which is exemplarily applied to the iso- and syndio-tactic poly(methyl methacrylate). A variety of thermomechanical properties of the two stereoregular polymer bulks are reasonably reproduced by the extensive molecular dynamics simulations with the so-parameterized CG potentials. In particular, the attractive nature of electrostatic interactions and tacticity effects on glass transition temperatures (T) are well captured. Furthermore, stronger electrostatic interactions lead to higher mass density and bulk modulus, and their effects on Young's modulus, Poisson's ratio, and shear modulus depend upon the chain tacticity. It is also demonstrated that all these elastic constants can be effectively modulated by imposing external electric field. The proposed multiscale scheme can be very valuable to molecular designs of polar polymer materials.
多尺度粗粒化（CG）模型有望在复杂聚合物的分子模拟中发挥关键作用。然而，这对准确模拟其热机械性能构成了巨大挑战，为此CG势需要具备出色的代表性和可转移性。在这项工作中，引入了虚拟位点和弹性网络键来改进基于结构和体积性质的CG模型，包括显式静电相互作用，并将其示例性地应用于等规和间规聚（甲基丙烯酸甲酯）。通过使用如此参数化的CG势进行广泛的分子动力学模拟，合理地再现了两种立构规整聚合物本体的各种热机械性能。特别是，很好地捕捉到了静电相互作用的吸引性质以及立构规整度对玻璃化转变温度（T）的影响。此外，更强的静电相互作用导致更高的质量密度和体积模量，它们对杨氏模量、泊松比和剪切模量的影响取决于链的立构规整度。还证明了通过施加外部电场可以有效地调节所有这些弹性常数。所提出的多尺度方案对于极性聚合物材料的分子设计可能非常有价值。
