Molecular Dynamics Simulation of Confined Polymer Melts
Molecular Dynamics Simulation of Confined Polymer Melts
复制标题
受限聚合物熔体的分子动力学模拟
DOI：
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发表时间：
2007
影响因子：
1
通讯作者：
Han, Charles C.
中科院分区：
文献类型：
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作者：
Jin Xi-Gao;Liao Qi;Li Yi-Jie;Wei Dong-Shan;Han, Charles C.
我们提出了两个粗糙壁之间的聚合物熔体的分子动力学模拟的结果。对Lennard-Jones颗粒的粗粒珠弹簧链进行了模拟。结果表明，对于链段较短的受限聚合物熔体体系，最长弛豫时间随膜厚的增加而减小;对于链段较长的受限聚合物熔体体系，弛豫时间随膜厚的增加先减小后增大到体相值。我们推测了这一独特现象的起源，并得出结论：随着膜厚的减小，受限系统中的长链从三维空间的纠缠态转变为近二维空间的分离态。重叠参数被用来解释这个过渡过程。我们发现，对于较长的聚合物链，在较厚的薄膜中，纠缠效应决定了弛豫时间，而在较薄的薄膜中，限制效应主导了弛豫时间。
We present the results of molecular dynamics simulations of polymer melts confined between two rough walls. Simulations were performed for the coarse-grained bead-spring chains of Lennard-Jones particles. The results show that, the longest relaxation time decreases with increasing the film thickness for the confined polymer melt systems with relative short chains; while for the confined systems with longer chains, the relaxation time decreases first and then increases to the bulk value when increasing the film thickness. We speculate on the origin of this unique phenomenon and conclude that longer chains in the confined systems change from the entangled state in three-dimensional space to the segregated state in nearly two-dimensional space with the decrease of film thickness. The overlap parameter is used to interpret this transitional process. We find that, for the longer polymer chains, entanglement effect determines the relaxation time in thicker films, while confinement effect dominates the relaxation in thinner films.