A computer simulation of charged particles in solution. II. Polyion diffusion coefficient

Abstract

A computer simulation study was conducted on the effects of the polyion–small ion electrostatic interaction upon the translational diffusion of polyions in polyelectrolyte solutions at thermodynamic equilibrium. This interaction increased the polyion diffusion coefficient and the increase was strongly dependent upon the polyion charge and size, and the small ion charge and mobility, while only slightly affected by changes in the polyion concentration. The increase was largest when there were only enough counterions to balance the charge of the polyions. Increasing the number of counterion–byion pairs per polyion decreased the polyion diffusion coefficient toward its uncharged value. The computer results were markedly different from those predicted by the self-consistent field theory of Stephen and a comparison of the two is presented.