ELECTROSTERIC STABILIZATION OF COLLOIDAL LATEX DISPERSIONS

Experimental stability domains of monodisperse aqueous latices, with and without steric stabilizers, are determined in terms of early-stage kinetics of flocculation using photon correlation spectroscopy. Dispersion stability as a function of electrolyte concentration and counterion valence is investigated. A low molar mass poly(ethylene oxide)/poly(propylene oxide) block copolymer is used as the steric stabilizer. Aggregation is induced by the addition of indifferent electrolyte. The rates of aggregate formation are expressed in terms of a stability ratio and interpreted in terms of the particle pair interaction potential function. For the system investigated both electrostatic and steric repulsions are found to be important in maintaining dispersion stability. Consistent with earlier results, systems with adsorbed block copolymer are found to increase the critical coagulation concentration for fast aggregation by nearly an order of magnitude. © 1993 by Academic Press, Inc.