Soap-free emulsion polymerization of n-butyl acrylate: Copolymerization with 1,1-(dimethyl)-1- (3-methacryloxyethyl)-1-(sulfopropyl)ammonium betaine

Emulsifier‐free emulsion polymerization of n‐butyl acrylate has been performed in the presence of a polymerizable sulfobetaine monomer, 1,1‐(dimethyl)‐1‐(3‐methacryloxyethyl)‐1‐(sulfopropyl)ammonium betaine (SPE). An investigation of the effect of various salts (NaCl, NaHCO3, Na2CO3, and NaH2PO4) on the emulsifier‐free emulsion polymerization of n‐butyl acrylate revealed that the type and quantity of salt is important in determining the size and size distribution of the final latex particles. In the case of the copolymerizations, control of the monomer feeding protocol (batch vs. semicontinuous and unseeded vs. seeded reactions) and of the ionic strength of the reaction mixture via addition of electrolytes allowed the preparation of stable latexes at 10% solids content with controllable particle size distributions. The results indicate that the amphiphilic sulfobetaine is able to stabilize the latex in much the same way as a polymerizable surfactant or an ionic comonomer. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 227–236, 1998