ADSORPTION OF POLYAMPHOLYTES ON POLYSTYRENE LATEX - EFFECT ON COLLOIDSTABILITY

The interfacial characteristics of low-charge-density polyelectrolytes and polyampholytes synthesized by a microemulsion polymerization tech nique have been investigated. Terpolymers of acrylamide (AM, neutral s egment), [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MADQUAT , positively charged segment), and sodium 2-(acrylamido)-2-methyl prop anesulfonate (NaAMPS, negatively charged segment) and copolymers of AM and MADQUAT as well as of MADQUAT and NaAMPS were adsorbed on a negat ively charged polystyrene latex. The zeta potential at full surface co verage was determined and analyzed as a function of the surface charge excess of the colloid-polymer complex. The domains of colloidal insta bility were determined and the rate of destabilization was studied for the different systems at the optimum flocculation concentration. A de viation from the usual polyelectrolyte behavior was found for the copo lymers and the terpolymers, which may be attributed to the reversible character of the aggregation processes resulting from a progressive mo dification of the characteristics of the adsorbed layer. (C) 1995 Acad emic Press, Inc.