Measurements of charge nonuniformity on polystyrene latex particles

The experimental technique of rotational electrophoresis, similar in principle to standard translational electrophoresis, has been developed to quantify the charge nonuniformity on Brownian colloidal particles. Experiments were conducted on doublets of 4.5 mum polystyrene latex particles under various solution conditions, finding variations in zeta potential on individual particle surfaces of 50-75% of the average zeta potentials. Significant charge nonuniformity was found for all systems studied, indicating that charge nonuniformity might be critical in many colloidal applications.