Preparation of latex particles by emulsion polymerization with amphoteric surfactants and interactions of latex particles thus prepared and pigments

Abstract

The emulsion polymerization of styrene has been studied in the presence of an amphoteric surfactant such as Nε{lunate}-lauroyl-Nα,Nα-dimethyl-lysine (DMLL) and N,N-dimethyl-n-laurylbetaine (LNB). The rate of polymerization and the concentration of latex particles generated are both proportional to the 0.6-power of the surfactant concentration. The particle size of the latices diminished as the concentration of the surfactant increased. The influence of the physicochemical properties of aqueous solutions of the surfactant on the emulsion polymerization at various pH values has also been discussed. Such properties significantly affect the characteristics of the latex particles formed at the various pH values studied. In order to elucidate the interaction between latex particles prepared in the presence of amphoteric surfactants and inorganic pigments, the zeta potentials and the turbidity of various mixed dispersions have been measured. It is shown that when the latex and pigment particles possess opposite charges, the mixed dispersions undergo heterocoagulation with redispersion occurring on increasing the number of latex particles in the system. © 1988.