Uneyama Takashi
JST-PRESTO, and Department of Materials Physics, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8603, Japan.
J Phys Chem B. 2025 Jan 9;129(1):506-523. doi: 10.1021/acs.jpcb.4c06118. Epub 2024 Dec 17.
We propose a highly coarse-grained simulation model for crystalline polymer solids with lamellar structures. The mechanical properties of a crystalline polymer solid are mainly determined by the crystalline lamellar structures. This means that coarse-grained models rather than fine-scale molecular models are suitable to study the mechanical properties. We model a crystalline polymer solid by using highly coarse-grained particles, of which the size is comparable to the crystalline layer thickness. One coarse-grained particle consists of multiple subchains and is much larger than monomers. Coarse-grained particles are connected by bonds to form a network structure. Particles are connected by soft but ductile bonds to form a rubber-like network. Particles in the crystalline region are connected by hard but brittle bonds. Brittle bonds are broken when large deformations are applied. We perform uniaxial elongation simulations based on our coarse-grained model. As the applied strain increases, crystalline layers are broken into pieces and nonaffine and collective motions of broken pieces are observed. Our model can successfully reproduce yield behaviors that are similar to typical crystalline polymer solids.
我们提出了一种用于具有层状结构的结晶聚合物固体的高度粗粒化模拟模型。结晶聚合物固体的力学性能主要由结晶层状结构决定。这意味着粗粒化模型而非精细尺度的分子模型适合用于研究力学性能。我们通过使用高度粗粒化的粒子对结晶聚合物固体进行建模，这些粒子的尺寸与结晶层厚度相当。一个粗粒化粒子由多个子链组成，比单体大得多。粗粒化粒子通过键连接形成网络结构。粒子通过柔软但有韧性的键连接形成类似橡胶的网络。结晶区域中的粒子通过坚硬但易碎的键连接。当施加较大变形时，易碎键会断裂。我们基于粗粒化模型进行单轴拉伸模拟。随着施加应变的增加，结晶层破碎成碎片，并观察到碎片的非仿射和集体运动。我们的模型能够成功再现与典型结晶聚合物固体相似的屈服行为。
