Monte Carlo Simulation of Polymer Diffusion in a Disordered Media

Abstract

In this paper we presented Monte Carlo simulations of polymer diffusion in a disordered media. A Monte Carlo (MC) simulation method in two dimensions with a bond fluctuation model (BFM) has been used to achieve this goal . In polymer diffusion, we present a new effective algorithm to simulate dynamic properties of polymeric systems confined to lattice. The algorithm displays Rouse behavior for all spatial dimensions. The systems are simulated by bond fluctuation method to study both the static and dynamic properties of the polymer chains. For static properties we calculated the average mean-square end-to-end distance hR2(N)iand the mean-square radius of gyration hRg 2(N)i. In the absence of obstacles (free media) both the end-to-end distance and the radius of gyration are proportional to some power of the number of monomers (N), hR2(N)i ∝ N 3/2 and hRg 2(N)i ∝ N 3/2. However in the presence of obstacles, the scaling exponent changes with the concentration of the obstacles. The end-to-end distance of the polymer increases, as concentration(c) increases. As the concentration of the obstacles increases, the bead obstacles close to the monomers, this causes the polymers to stretch. In the presence of obstacles the mean radius of gyration increases, and the universal power law the scaling deviates from the universal power law relations. For disordered systems diffusion is anomalous, and the mean-square displacement is proportional to a fractional power of time not equal to one. For dynamical properties we look at the mean-square displacement of the total chain. For short times the mean-square displacement of the monomers g1(t) and the mean-square displacement of the monomers relative to the chains center of mass g2(t) show the same behavior and for long times the mean-square displacement of the center of mass g3(t) takes over