Some factors involved in the preparation of uniform particle size latexes

Abstract

Abstract Some factors involved in the preparation of monodisperse polymer latexes by seeded emulsion polymerization are discussed. In this technique monomer and catalyst are added to a previously prepared latex; during the subsequent polymerization these seed particles grow to a larger size. A mathematical analysis has been developed relating the particle volume increase to particle size as a power function. Competitive particle growth has been determined experimentally by polymerizing monomer in a seed latex comprised of a mixture of two monodisperse latexes of different sizes. In these experiments the diameters of the smaller particles increase at a slightly greater rate than those of the larger ones. Therefore the final particle size distribution is narrower than that of the seed latex. In these growth experiments the concentration of emulsifier is also important. An illustrative example shows that excessive emulsifier initiates new particles and insufficient emulsifier causes coagulum.