DIFFUSION AND INTERACTION IN GELS AND SOLUTIONS .6. CHARGED SYSTEMS
DIFFUSION AND INTERACTION IN GELS AND SOLUTIONS .6. CHARGED SYSTEMS
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DOI：
10.1021/j100140a045
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发表时间：
1993-09-23
影响因子：
--
通讯作者：
LOFROTH, JE
中科院分区：
文献类型：
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作者：
JOHANSSON, L;SKANTZE, U;LOFROTH, JE
结果来自布朗动力学模拟和带相反电荷的聚合物系统中单价离子自扩散系数的实验测量。模拟是在有序和随机聚离子系统中进行的。有序系统由方形晶格上的平行直链组成，而在其他系统中，直聚合物链是随机取向的。在低聚合物浓度下，两种类型的系统获得的结果非常一致。然而，当聚离子浓度增加时，随机系统中的离子扩散比有序系统中的离子扩散慢。这表明观察到的结果来自于随机系统中存在的多离子距离的分布和链的相对方向。该解释基于聚离子之间的大量传输作为限速过程。模拟数据与实验结果定性一致。然而;实验结果还强调了空间阻碍的重要性，这可能是大离子和浓聚电解质系统中的主导效应。
Results are presented from Brownian dynamics simulations and from experimental measurements of self-diffusion coefficients of monovalent ions in systems of oppositely charged polymers. The simulations were carried out in ordered and in random polyion systems. The ordered systems consisted of parallel straight chains on a square lattice, while in the other systems the straight polymer chains were randomly oriented. At low polymer concentrations there was good agreement between the results obtained in both types of systems. However, when the polyion concentration was increased, the ion diffusion was slower in the random than in the ordered systems. It is suggested that the observed results emanate from the distribution of interpolyion distances and the relative orientation of the chains present in the random systems. The interpretation is based on the transport in the bulk between the polyions as the rate-limiting process. The simulation data are in qualitative agreement with the experimental results. However; the experimental results also emphasize the importance of steric obstruction, which can be the dominant effect for large ions and in concentrated polyelectrolyte systems.