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arXiv 0804.2221cond-mat.softcond-mat.mtrl-sci
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理解Polymer电解质中的节段动力学:计算机研究

Understanding Segmental Dynamics in Polymer Electrolytes: A Computer Study

Arijit Maitra, Andreas Heuer

摘要:

通过分析简正模,研究了聚氧化乙烯(PEO)在纯聚合物和聚合物电解质(PEO/LiBF $_4$)中的链段动力学。我们验证了劳斯理论的适用性,特别是对于聚合物电解质的动态异质性,所产生的阳离子-聚合物相互作用,改变沿链的流动性不均匀。我们发现,这两个系统的劳斯模式是正交的,尽管存在的非指数松弛的模式和违反高斯自相似的链。在聚合物电解质中的链段动力学的减速是合理的,由数量级增加的摩擦系数的那些单体,这是由阳离子结合。在一般情况下,对于电解质的劳斯预测的动态段(自由和/或绑定)同意,除了很短的时间。

英文摘要:

We study the segmental dynamics of poly(ethylene oxide) (PEO) from microscopic simulations in the neat polymer and a polymer electrolyte (PEO/LiBF$_4$) by analyzing the normal modes. We verify the applicability of the Rouse theory, specifically for the polymer electrolyte where dynamic heterogeneities, arising from cation-polymer interactions, alter the mobility non-uniformly along the chains. We find that the Rouse modes for both the systems are orthogonal despite the presence of non-exponential relaxation of the modes and violation of the Gaussian self-similarity of the chains. The slowdown of the segmental dynamics in the polymer electrolyte is rationalised by an order of magnitude increase in the friction coefficient for those monomers which are bound by cations. In general, for the electrolyte the Rouse predictions for the dynamics of segments (both free and/or bound) agree well except for very short times.

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