A transport model for swelling of polyelectrolyte gels in simple and complex geometries

A model for the swelling of polyelectrolyte gels in salt solutions is devel oped and solved numerically. The model accounts for the effect of network s tress, osmotic pressure, and electrical potential on the species diffusive flux. The osmotic pressure and the network stress are derived from the Helm holtz free energy of the system that is the sum of mixing, elastic, and ele ctrostatic components. One- and two-dimensional swelling in unconstrained a nd constrained geometries are simulated for a salt-solvent-polymer system. The transient and equilibrium fields of electrical potential, concentration s, deformation, and stress are obtained. Transient overshoots and non-unifo rmities in the residual profiles are predicted. (C) 2000 Elsevier Science L td. All rights reserved.