ABSTRACT
This chapter reviews the obtained results from Electric Light Scattering (ELS) with an emphasis on counterions dynamics. The electric double layer (EDL) around a colloid particle, in aqueous media, in the absence of an external field is in equilibrium. In electrophoresis, the polarization of EDL will produce an additional impeding force superimposed with the Stockes viscous force and electrophoretic retardation. The electrolyte concentration increase at the top of the particle and respective decrease at the bottom means a decrease and increase of EDL thickness, respectively. The polarization of polyelectrolytes in external electric fields could be regarded with a model combining Maxwell–Wagner and electrokinetic approach. ELS studies of model anisometric particles, coated with polyelectrolyte multilayers, have shown that the polarization of “condensed” counterions is responsible for the electro-optical effect. The theoretical models of EDL polarization processes and their relaxation times should be compared with the results obtained from ELS studies.
