Supermicron poly(butyl acrylate)/polystyrene core‐shell latexes

Abstract

Abstract Latex particles of up to 2 μm can be made by standard emulsion polymerization methods, but attempts at larger sizes usually results in a crop of smaller particles or coagulation of the latex. In this work, it is shown that use of an oil‐soluble initiator (2,2′ azodiisobutyronitrile [AIBN]) provides a means by which large (6 μm diameter) polybutyl acrylate latex particles can be made by sequential core‐shell polymerizations. It is suggested that the limited water solubility of AIBN decreases the formation of secondary particles and that the lower ionic strength of the water phase enhances stability of the latex compared to a conventional persulfate initiator. To further minimize formation of secondary particles, long reaction times and progressively larger proportions of seed latex are used in successive reactions. © 1992 John Wiley & Sons, Inc.