Effect of Chain Length Dispersity on the Mobility of Entangled Polymers.
Effect of Chain Length Dispersity on the Mobility of Entangled Polymers.
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DOI：
10.1103/physrevlett.121.057802
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发表时间：
2018-07
影响因子：
8.6
通讯作者：
Brandon L. Peters;K. Salerno;T. Ge;D. Perahia;G. Grest
中科院分区：
文献类型：
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作者：
Brandon L. Peters;K. Salerno;T. Ge;D. Perahia;G. Grest
虽然几乎所有关于缠绕聚合物熔体的理论和计算研究都集中在均匀的样品上，但聚合物合成路线总是导致分子量分布的分散性(Đ_{M}=M_(W)/M_(N)∼1.02-1.04)。在这里，使用聚乙烯的粗粒模型研究了分散性对缠绕的分散熔体的链迁移率的影响。用分子动力学模拟方法研究了链长服从舒尔茨-齐姆分布的聚合物熔体，其平均M_(W)=36 kg/Đ，Đ_{M}=1.0~1.16，时间为6 0 0~80 0μS.这一时间框架比达到扩散制度所需的时间要长。我们发现，在此范围内的分散性并不影响纠缠时间或管径。然而，在均匀分布Đ_{M}=1.0和Đ_{M}=1.02时，链的平均迁移率差异不大，但对于较大的Đ_{M}，最短的链的移动速度明显快于最长的链，为熔体提供了一个约束释放途径。
While nearly all theoretical and computational studies of entangled polymer melts have focused on uniform samples, polymer synthesis routes always result in some dispersity, albeit narrow, of distribution of molecular weights (Đ_{M}=M_{w}/M_{n}∼1.02-1.04). Here, the effects of dispersity on chain mobility are studied for entangled, disperse melts using a coarse-grained model for polyethylene. Polymer melts with chain lengths set to follow a Schulz-Zimm distribution for the same average M_{w}=36 kg/mol with Đ_{M}=1.0 to 1.16, were studied for times of 600-800 μs using molecular dynamics simulations. This time frame is longer than the time required to reach the diffusive regime. We find that dispersity in this range does not affect the entanglement time or tube diameter. However, while there is negligible difference in the average mobility of chains for the uniform distribution Đ_{M}=1.0 and Đ_{M}=1.02, the shortest chains move significantly faster than the longest ones offering a constraint release pathway for the melts for larger Đ_{M}.