Avramova K, Milchev A
Institute for Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
J Chem Phys. 2006 Jan 14;124(2):024909. doi: 10.1063/1.2151901.
We study the equilibrium properties of flexible polymer chains confined in a soft tube by means of extensive Monte Carlo simulations. The tube wall is that of a single sheet six-coordinated self-avoiding tethered membrane. Our study assumes that there is no adsorption of the chain on the wall. By varying the length N of the polymer and the tube diameter D we examine the variation of the polymer gyration radius Rg and diffusion coefficient Ddiff in soft and rigid tubes of identical diameter and compare them to scaling theory predictions. We find that the swollen region of the soft tube surrounding the chain exhibits a cigarlike cylindrical shape for sufficiently narrow tubes with D<<Rg. The observed scaling of static conformational properties with chain length N and tube diameter D follows the predictions of scaling theory and displays no significant difference between soft and rigid tubes. The Brownian dynamics of the polymer diffusion in a rigid tube is found to slow down in a tube with soft walls by an amount which depends on the Rg/D ratio albeit the relaxation time tau(parallel) for diffusive motion along the tube still scales as tau(parallel) proportional, N3.
我们通过广泛的蒙特卡罗模拟研究了限制在软管中的柔性聚合物链的平衡性质。管壁是由单层六配位自回避拴系膜构成的。我们的研究假设链在壁上没有吸附。通过改变聚合物的长度N和管直径D，我们研究了聚合物回转半径Rg和扩散系数Ddiff在直径相同的软管和刚性管中的变化，并将它们与标度理论预测进行比较。我们发现，对于D<<Rg的足够窄的管，围绕链的软管的膨胀区域呈现出雪茄状的圆柱形。观察到的静态构象性质随链长N和管直径D的标度遵循标度理论的预测，并且在软管和刚性管之间没有显示出显著差异。发现聚合物在刚性管中的布朗动力学在具有软壁的管中减慢的程度取决于Rg/D比，尽管沿管的扩散运动的弛豫时间tau(平行)仍然按tau(平行)∝N3标度。
