Modeling Entangled Dynamics: Comparison between Stochastic Single-Chain and Multichain Models
Modeling Entangled Dynamics: Comparison between Stochastic Single-Chain and Multichain Models
复制标题
DOI：
10.1021/ma802059p
复制
发表时间：
2009-06-23
期刊：
影响因子：
5.5
通讯作者：
Likhtman, Alexei E.
中科院分区：
文献类型：
--
作者：
Sukumaran, Sathish K.;Likhtman, Alexei E.
为了测试随机单链模型在描述纠缠聚合物的动力学的有效性，我们系统地比较这样一个模型-弹簧模型-多链模型解决使用随机分子动力学（MD）模拟（Kremer-Grest模型）。比较涉及调查，如果单链模型可以充分描述一个范围内的链长的微观动力学和宏观流变量。选择一个特定的链长度的弹簧模型，最好地再现一组单体的均方位移的参数值是通过拟合MD数据来确定。使用相同的一组参数，我们然后测试，如果预测的均方位移为其他链长同意与MD计算。随后，我们从两个模型的一系列链长的时间依赖性的应力松弛模量的比较。在确定了原来的滑动弹簧模型在描述的静态结构的聚合物链中看到的MD的限制后，我们纠正这一点，通过引入成对的排斥潜力的单体之间的链。差协议的均方单体位移在短时间内可以通过使用广义朗之万方程的动力学纠正，并导致显着改善协议。
To test the effectiveness of stochastic single-chain models in describing the dynamics of entangled polymers, we systematically compare one such model-the slip-spring model-to a multichain model solved using stochastic molecular dynamics (MD) simulations (the Kremer-Grest model). The comparison involves investigating if the single-chain model can adequately describe both a microscopic dynamical and a macroscopic rheological quantity for a range of chain lengths. Choosing a particular chain length in the slip-spring model, the parameter values that best reproduce the mean-square displacement of a group of monomers is determined by fitting to MD data. Using the same set of parameters we then test if the predictions of the mean-square displacements for other chain lengths agree with the MD calculations. We followed this by a comparison of the time dependent stress relaxation moduli obtained from the two models for a range of chain lengths. After identifying a limitation of the original slip-spring model in describing the static structure of the polymer chain as seen in MD, we remedy this by introducing a pairwise repulsive potential between the monomers in the chains. Poor agreement of the mean-square monomer displacements at short times can be rectified by the use of generalized Langevin equations for the dynamics and resulted in significantly improved agreement.