SOAP-FREE EMULSION POLYMERIZATION OF N-BUTYL ACRYLATE - COPOLYMERIZATION WITH L)-1-(3-METHACRYLOXYETHYL)-1-(SULFOPROPYL)AMMONIUM BETAINE

Emulsifier-free emulsion polymerization of n-butyl acrylate has been p erformed in the presence of a polymerizable sulfobetaine monomer, l)-1 -(3-methacryloxyethyl)-1-(sulfopropyl)ammonium betaine (SPE). An inves tigation of the effect of various salts (NaCl, NaHCO3, Na2CO3, and NaH 2PO4) on the emulsifier-fi ee emulsion polymerization of n-butyl acryl ate revealed that the type and. quantity of salt is important in deter mining the size and size distribution of the final latex particles. In the case of the copolymerizations, control of the monomer feeding pro tocol (batch vs. semicontinuous and unseeded vs. seeded reactions) and of the ionic strength of tl-le reaction mixture via addition of elect rolytes allowed the preparation of stable latexes at 10% solids conten t with controllable particle size distributions. The results indicate that the amphiphilic sulfobetaine is able to stabilize the latex in mu ch the same way as a polymerizable surfactant or an ionic comonomer. ( C) 1998 John Wiley & Sons, Inc.