Soap-free cationic emulsion copolymerization of styrene and butyl acrylate with comonomer in the presence of alcohols

Preparation of a cationic polymer latex of styrene and butyl acrylate with comonomer N,N-dimethyl, N-butyl,N-methacryloloxylethyl ammonium bromide (DBMEA) was carried out by soap-free emulsion polymerization. The effect of reaction conditions such as the ratio of methanol to water, DBMEA concentration, AIBA concentration and ionic strength on properties of copolymer particles was studied. The results showed that the average diameter (D-w) decreased with increasing of AIBA and DBMEA concentration; D-w decreased first then increased with increasing of methanol content; variation of the ionic strength led to a variation in the particle number (N-P) and D-w because of the competition of two kinds of nucleation mechanisms. The same trend was found in the polymerization taking in pure water. The MWD was bimodal during the particle growth period. These results suggest that the particles can be generated through two particle-formation mechanisms, micelle nucleation and homogeneous nucleation. (C) 2003 Wiley Periodicals, Inc.