SYNTHESIS, PURIFICATION AND CHARACTERIZATION OF CATIONIC LATTICES PRODUCED BY THE EMULSION COPOLYMERIZATION OF STYRENE WITH 3-(METHACRYLAMIDINOPROPYL)TRIMETHYLAMMONIUM CHLORIDE

A study was made of the effect of varying the amount of 3-(methacryl-amidinopropyl)trimethylammonium chloride (MAD) on the emulsion copolymerization of styrene and MAD with azo-bis(isobutyramidine hydrochloride) as initiator. The addition of MAD accelerated the polymerization and decreased the particle size. Cleaning of these latices in order to remove polyelectrolyte not incorporated in the latex particles was found to be tedious. Serum replacement, diafiltration and centrifugation appeared to be unsatisfactory since desorption of polyelectrolyte was still observed after standing or stirring. A combination of centrifugation and treatment with silica appeared to clean the latices to a satisfactory level (expressed as [N+] < 5 x 10(-7) mol/dm3). Surface charge density, as determined by conductometric acid-base titrations, rose slightly on increasing the initial MAD concentration. Shot-growth (two-step) emulsion polymerization or the use of a cross-linking agent (divinylbenzene) hardly affected the surface charge density.