Topological effects in ring polymers. II. Influence Of persistence length
Topological effects in ring polymers. II. Influence Of persistence length
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环聚合物中的拓扑效应。
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
Michael E. Cates
中科院分区：
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作者：
Marcus Müller;J. Wittmer;Michael E. Cates
通过三维晶格模型的动态Monte Carlo模拟，研究了环状聚合物在其自身熔体中的拓扑约束和持续长度的相互作用。我们问，如果结果是一致的渐近制度的环的行为像（紧凑）晶格动物在一个自洽的网络拓扑约束的相邻环。调整持久长度提供了一种有效的途径来增加这个平均场图像所需的环重叠：环大小的有效弗洛里指数随着持久长度的增加而减小到nu以下，类似于1/3。证据提供了一个额外的特征长度尺度d（t）的出现约N 0，只有弱依赖于持久性长度和远大于排除量筛选长度xi。当距离大于d（t）时，环的构象性质受拓扑相互作用的影响;当距离小于d（t）时，环和它们的线性链变得相似。(At小于xi的距离，两种结构是相同的。然而，这两个极限之间的交叉是复杂和广泛的，作为局部分形维数的详细讨论（例如，从静态结构因子获得）显示。这是由于各种交叉效应导致的，即使对于此处提供的最大环尺寸（N=1024），我们也无法将其分开。拓扑相互作用的增加也会影响动力学性质。均方位移及其分布主要取决于环的重叠，并显示存在额外的尺寸和时间尺度的证据。环的扩散常数从低重叠柔性环的有效D（N）约N-1.22下降到强重叠半柔性环的有效D（N）约N-1.68。
The interplay of topological constraints and the persistence length of ring polymers in their own melt is investigated by means of dynamical Monte Carlo simulations of a three-dimensional lattice model. We ask if the results are consistent with an asymptotically regime where the rings behave like (compact) lattice animals in a self-consistent network of topological constraints imposed by neighboring rings. Tuning the persistence length provides an efficient route to increase the ring overlap required for this mean-field picture to hold: The effective Flory exponent for the ring size decreases down to nu less, similar1/3 with increasing persistence length. Evidence is provided for the emergence of one additional characteristic length scale d(t) approximately N0, only weakly dependent on the persistence length and much larger than the excluded volume screening length xi. At distances larger than d(t) the conformational properties of the rings are governed by the topological interactions; at smaller distances rings and their linear chain counterparts become similar. (At distances smaller than xi both architectures are identical.) However, the crossover between both limits is intricate and broad, as a detailed discussion of the local fractal dimension (e.g., obtained from the static structure factor) reveals. This is due to various crossover effects which we are unable to separate even for the largest ring size (N=1024) presented here. The increased topological interactions also influence the dynamical properties. Mean-square displacements and their distributions depend crucially on the ring overlap, and show evidence of the existence of additional size and time scales. The diffusion constant of the rings goes down from effectively D(N) approximately N-1.22 for flexible rings with low overlap to D(N) approximately N-1.68 for strongly overlapping semiflexible rings.