SURFACE CHARACTERISTICS OF POLYSTYRENE LATEX-PARTICLES AND COMPARISONWITH STYRENE-BUTADIENE COPOLYMER LATEX-PARTICLES USING DYNAMIC LIGHT-SCATTERING AND ELECTROPHORETIC LIGHT-SCATTERING MEASUREMENTS

The surface characteristics of two samples of polystyrene latex partic les of uniform size, one having only sulfate and the other both sulfat e and aromatic amino groups, have been examined using dynamic light sc attering and electrophoretic light scattering measurements. The surfac e properties are compared with those of styrene-butadiene copolymer la tex particles having both sulfate and carboxyl groups. The differences in the overall dimensions of the latex particles suggest that the hai ry layers at the latex surfaces determine the observed dynamic behavio r, The surface polymer composition and the surface charge density deri ved from ionizable groups strongly influence the adsorption of inorgan ic electrolyte ions, These properties also determine the hydration at the latex surface and lead to the temperature dependence I independenc e of the particle dimensions. Amination/carboxylation of the latex par ticles results in surface properties which are strongly dependent on t he pH of the medium and thus produce complex changes in both overall d imension and mobility with changing pH. (C) 1996 Academic Press, Inc.