Polymer chain stiffness vs. excluded volume: A Monte Carlo study of the crossover towards the worm-like chain model
Polymer chain stiffness vs. excluded volume: A Monte Carlo study of the crossover towards the worm-like chain model
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DOI：
10.1209/0295-5075/92/28003
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发表时间：
2010-10-01
期刊：
影响因子：
1.8
通讯作者：
Binder, Kurt
中科院分区：
文献类型：
--
作者：
Hsu, Hsiao-Ping;Paul, Wolfgang;Binder, Kurt
当聚合物链的局部固有刚度在很宽的范围内变化时，我们可以观察到从刚性棒状行为到（几乎）高斯随机卷曲的交叉，以及向良溶剂中自回避行走的进一步交叉。使用修剪丰富的 Rosenbluth 方法 (PERM) 研究最多 N-b = 50000 步的自回避行走和可变灵活性，测试了 Kratky-Porod 模型的适用性。给出了沿着链轮廓的大距离 s 的键取向相关性 < cos theta(s)> 非指数衰减的证据，与链刚度无关。另一方面，对于瓶刷聚合物，实验上的刚度通过侧链的长度变化，结果表明，这些圆柱形刷（具有柔性主链）不是由 Kratky-Porod 蠕虫状链模型描述的，因为对于所有实际感兴趣的条件，它们的持久长度（大致）与其横截面半径成正比。版权所有 (C) EPLA，2010
When the local intrinsic stiffness of a polymer chain varies over a wide range, one can observe both a crossover from rigid-rod-like behavior to (almost) Gaussian random coils and a further crossover towards self-avoiding walks in good solvents. Using the pruned-enriched Rosenbluth method (PERM) to study self-avoiding walks of up to N-b = 50000 steps and variable flexibility, the applicability of the Kratky-Porod model is tested. Evidence for non-exponential decay of the bond-orientational correlations < cos theta(s)> for large distances s along the chain contour is presented, irrespective of chain stiffness. For bottle-brush polymers on the other hand, where experimentally stiffness is varied via the length of side-chains, it is shown that these cylindrical brushes (with flexible backbones) are not described by the Kratky-Porod worm-like chain model, since their persistence length is (roughly) proportional to their cross-sectional radius, for all conditions of practical interest. Copyright (C) EPLA, 2010