Electro-optics of polyelectrolyte multilayers on colloidal particles

Electric light scattering method is used to study electrical properties and structure of polyelectrolyte multilayer films adsorbed on non-spherical particles in the absence of salt. Attention is focused on the advantage of electro-optics to give information simultaneously on the dynamics of counterions and the thickness of the multilayer films adsorbed on the particles in stabilized suspensions. Based on the electro-optical experiment, it is demonstrated that polarization of counterions along the chains of the last-deposited polymer governs the behavior of the whole multilayer film. Evidence is given that the film thickness can increase exponentially with the number of deposited layers even in the absence of salt when a fully charged polyelectrolyte is combined with a weakly charged one. Examples are presented for electro-optical characterization of multilayer films on colloidal particles with potential applications in anticorrosion coatings and medicine.