Surface characteristics of polystyrene latex particles and comparison with styrene-butadiene copolymer latex particles using dynamic light scattering and electrophoretic light scattering measurements

The surface characteristics of two samples of polystyrene latex particles of uniform size, one having only sulfate and the other both sulfate and aromatic amino groups, have been examined using dynamic light scattering and electrophoretic light scattering measurements. The surface properties are compared with those of styrene-butadiene copolymer latex particles having both sulfate and carboxyl groups. The differences in the overall dimensions of the latex particles suggest that the hairy layers at the latex surfaces determine the observed dynamic behavior, The surface polymer composition and the surface charge density derived from ionizable groups strongly influence the adsorption of inorganic electrolyte ions, These properties also determine the hydration at the latex surface and lead to the temperature dependence I independence of the particle dimensions. Amination/carboxylation of the latex particles results in surface properties which are strongly dependent on the pH of the medium and thus produce complex changes in both overall dimension and mobility with changing pH. (C) 1996 Academic Press, Inc.