Energy Renormalization for Coarse‐Graining Polymers with Different Fragilities: Predictions from the Generalized Entropy Theory,Macromolecular Theory and Simulations

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Energy Renormalization for Coarse‐Graining Polymers with Different Fragilities: Predictions from the Generalized Entropy Theory
Macromolecular Theory and Simulations ( IF 1.8 ) Pub Date : 2020-01-03 , DOI: 10.1002/mats.201900051
Wen‐Sheng Xu ₁ , Wenjie Xia ₂

Affiliation

Bottom‐up prediction of physical performance of glass‐forming (GF) polymers via coarse‐grained (CG) modeling is challenging because these CG models normally experience significantly altered dynamics that strongly vary with temperature. Building upon the recently developed energy‐renormalization (ER) coarse‐graining method based on molecular dynamics simulations, generalized entropy theory (GET) is employed to theoretically investigate the influence of fundamental molecular parameters on CG modeling of polymers having different glass “fragilities” Taking a linear polymer melt as a model system within the GET framework, it is shown that the chain bending rigidity and cohesive interaction play critical roles in the glass formation of polymers and their CG analogs. To coarse‐grain polymers having a higher fragility index, it requires greater magnitudes of ER factor ε_CG to rescale the cohesive interaction strength under coarse‐graining and thus recover the atomistic relaxation dynamics over a wide temperature range. The GET further predicts that a higher degree of coarse‐graining generally requires greater magnitudes of ε_CG due to the influence of loss of configuration entropy s_c on the dynamics. GET analyses herein theoretically demonstrate the efficacy of the ER method toward building a multiscale temperature transferable modeling framework for GF polymers, and confirm the importance of preserving s_c in CG modeling of dynamics of soft materials.

中文翻译：

具有不同脆性的粗粒聚合物的能量重正化：基于广义熵理论的预测

自下而上地通过粗粒度（CG）建模预测玻璃成型（GF）聚合物的物理性能具有挑战性，因为这些CG模型通常会经历显着变化的动力学，且动力学会随温度而强烈变化。在最近开发的基于分子动力学模拟的能量重整化（ER）粗粒度方法的基础上，广义熵理论（GET）用于理论研究基本分子参数对具有不同玻璃“易碎性”聚合物的CG模型的影响线性聚合物熔体作为GET框架内的模型系统，表明链弯曲刚度和内聚相互作用在聚合物及其CG类似物的玻璃形成中起关键作用。对于具有较高脆性指数的粗粒聚合物，_CG可在粗粒度下重新调整内聚相互作用强度，从而在较宽的温度范围内恢复原子弛豫动力学。的GET进一步预测，更高程度的粗粒化的通常需要ε的量值更大_CG由于配置熵的损失的影响小号_Ç上的动态变化。本文的GET分析从理论上证明了ER方法对于建立GF聚合物的多尺度温度可传递建模框架的有效性，并确认了在软材料动力学的CG建模中保留s _c的重要性。

更新日期：2020-01-03

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