  A theoretical model of electromigrative, diffusive and convectivetransport
polymer-gel composites is presented. Bulk properties are derived from the
standard electrokinetic model with an impenetrable charged sphere embedded in
an electrolyte-saturated Brinkman medium. Because the microstructure can be
carefully controlled, these materials are promising candidates for enhanced
gel-electrophoresis, chemical sensing, drug delivery, and microfluidic pumping
technologies. The methodology provides `exact' solutions for situations where
perturbations from equilibrium are induced by gradients of electrostatic
potential, concentration and pressure. While the volume fraction of the
inclusions should be small, Maxwell's well-known theory of conduction suggests
that the theory may also be accurate at moderate volume fractions. In this
work, the model is used to compute ion fluxes, electrical current density, and
convective flow induced by an applied electric field. The
electric-field-induced (electro-osmotic) flow is a sensitive indicator of the
inclusion zeta-potential and size, electrolyte concentration, and Darcy
permeability of the gel, while the electrical conductivity increment is most
often independent of the polymer gel, and is much less sensitive to particle
and electrolyte characteristics.
