ADSORPTION OF POLYELECTROLYTES AND STABILITY OF LATEX SUSPENSIONS

The adsorption of polyethylenimine and carboxymethylcellulose sodium salts from aqueous electrolyte solutions and its effect on the sedimentation rate, volume of sediment, electrokinetic potential and degree of aggregation of homo-disperse polystyrene and melamineformaldehyde copolymer particles were investigated. The adsorption isotherms are of high-affinity type and may be described by the Hesselink theory of polyelectrolyte adsorption. Starting from the calculated values of the adsorption layer thickness and the segment densities in polymer coils and adsorption layers a considerable deformation of polymers during adsorption was assumed. It was shown that the flocculation of suspensions by polyelectrolytes takes place far from the isoelectric point of particles. The role of electrostatic, structural and steric forces in the mechanism of stabilization of dispersions by oppositely charged polyelectrolytes is discussed.