Bulk Counterion Diffusion in Rod‐Like Polyelectrolyte Solutions

Abstract

AbstractThe bulk counterion diffusion along a charged rod‐like polyion is considered in the light of the linearized Poisson‐Boltzmann equation of the Gouy‐Chapman double layer theory to estimate the contribution of this process on the high‐frequency dielectric dispersions of dilute polyelectrolyte solutions. This model, which has been previously applied to colloidal suspensions of charged spherical particles, allows to predict the functional form of the dependence of the dielectric and conductometric parameters on the bulk counterion concentration and on the dielectric constants of the polyion domain and electrolyte solution, in the limit of very small polyion content. The derived expressions for the dielectric and conductivity increments show that the influence of the bulk counterion diffusion is generally very small and in particular conditions negligible. Nevertheless these effects may be important correcting factors to take into account in the accurate interpretation of dielectric measurements.