Low-Frequency Dielectric Responses, Static Conductivities, and Streaming Potentials of Polymer-Coated Latex Dispersions and Porous Plugs

Abstract

The low-frequency permittivity and conductivity increments and the static conductivity of well-characterized latex dispersions and plugs have been measured over a wide range of ionic strengths. We have investigated the effects of adsorption of the neutral polymer polyethylene oxide on these electrodynamic phenomena. It is shown that the counterion mobility in the double layer is significantly reduced by the adsorbed polymer. A model is developed to describe the retarded motion of ions in the gel-like polymer layer, which is considered a Brinkman fluid. The required ionic and polymer distribution functions are obtained from a self-consistent field model. Furthermore, ζ-potentials were inferred from streaming potentials of close-packed latex plugs. Since a significant part of the conduction is due to ions behind the shear plane, it was necessary to make use of the plug conductivity data in obtaining the correct ζ-potentials, especially at low ionic strengths. The ζ-potentials of the polymer-coated surface a...