Collision of a field-driven polymer with a finite-sized obstacle: A Brownian dynamics simulation
Collision of a field-driven polymer with a finite-sized obstacle: A Brownian dynamics simulation
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DOI：
10.1021/ma981049g
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发表时间：
1999-02-09
期刊：
影响因子：
5.5
通讯作者：
Sevick, EM
中科院分区：
文献类型：
--
作者：
Saville, PM;Sevick, EM
我们研究了在存在热噪声的情况下，由N个大小为a的单体组成的场驱动的高分子链与半径为R的有限大小障碍物的碰撞问题。我们发现有两种不同的解链机制：“脱钩”和“滚离”。脱钩机制的特征是释放时链的强烈伸展和脱钩时间随链长度的变化而变化。相反，滚落机制不会对链构象施加强烈的拉伸，并且不依赖于链的大小，而是依赖于障碍的大小。因此，一系列小的、间隔很大的柱子的宏观流动性提供了根据链条的大小分离链条的机会，而一系列大型圆形障碍物的链条流动性提供了关于障碍物大小的信息。虽然扩散在小时间尺度上很重要，但当无量纲场强定义为β=E lambda a/(k(B)T)(其中lambda是电荷密度，E是场强)时，扩散对任何大小R的圆形障碍物的释放动力学没有显著贡献。
We study the problem of a field-driven polymer chain of N monomers of size a colliding with a finite-sized obstacle of radius R in the presence of thermal noise. We show that there are two different mechanisms for chain release from the obstacle: "unhooking" and "rolling off". The unhooking mechanism is characterized by strong stretching of the chains at release and an unhooking time which scales with chain length. In contrast, the "rolling-off" mechanism does not impose strong stretching on the chain conformation and is dependent not upon the size of the chain, but rather upon the size of the obstacle. Thus, macroscopic mobility in an array of small, widely spaced posts provides an opportunity to separate chains according to their size, while chain mobility in an array of large circular obstacles provides information on the size of the obstacles. While important at small time scales, diffusion does not contribute significantly to the release kinetics from circular obstacles of any size R when the dimensionless field strength, defined as beta = E lambda a/(k(B)T) where lambda is charge density and E is field strength, is beta N > a/R.