Influence of polymer ionization degree on solute diffusion in polyelectrolyte gels

The ability of an obstruction-scaling model of solute diffusion to account for solute diffusivity in polyelectrolyte gels composed of semiflexible chains is presented. The diffusion of FITC-dextran in poly(acrylic acid) gels was measured at different pH conditions to determine the effect of the ionization degree of the poly(acrylic acid) on the diffusivity of the FITC-dextran. The obstruction-scaling model, as well as a hydrodynamic-based model and a jumping frequency model, was applied to the data. It was determined through regression analysis that the obstruction-scaling approach provided a better fit and could effectively account for the observed effect of the variation in the ionization degree on solute diffusivity.