Modeling solute diffusion in aqueous polymer solutions

There are numerous models describing solute diffusion in polymer solutions. An analysis of these models demonstrates that none can provide a consistent explanation of the phenomenon observed for solutes that can be modeled as essentially solid spheres, For this reason, a new model based on a physical obstruction approach is presented. In this model, solute movement in the presence of polymer chains is assumed to be governed by the probability of the solute molecule encountering a series of openings between the chains larger than its hydrodynamic radius. The model is tested against data taken from the literature for a series of polymer solutions and solute probes and found to provide good agreement to the effects of solute size, polymer concentration, and polymer flexibility. (C) 2002 Published by Elsevier Science Ltd.