Emulsifier-free emulsion copolymerization of styrene with quaternary ammonium cationic monomers

Emulsifier-free emulsion binary copolymerizations of styrene with four type s of quaternary ammonium cationic monomers, diallyldimethylammonium chlorid e (DADMAC), (3-(methacryloylamino) propyl) trimethyl ammonium chloride (MAP TAC), (2-methacryloyloxy) ethyl) trimethyl ammonium chloride (MATMAC), and vinylbenzyl trimethyl ammonium chloride (VBTMAC), were conducted at 70 degr ees C. 2, 2'-azobis (2-methylpropionamidine) dihydrochloride (V50) and pota ssium persulphate (KPS) were used as cationic and anionic initiator, respec tively. Ternary copolymerizations were also carried out in the presence of acrylamide as a second comonomer. Monomer conversions were followed by ultr aviolet spectroscopy and the polymer microparticles were characterized usin g photon correlation spectroscopy, electrophoresis, colloid titration, and scanning electron microscopy. The results indicated that VBTMAC and MATMAC were highly reactive in the copolymerization with styrene whereas the incor poration of DADMAC was slow. MAPTAC had an intermediate reactivity. Binary copolymerization with VBTMAC, MATMAC, and MAPTAC produced particles smaller in size, but higher in surface-charge density, than styrene homopolymer pa rticles. However, significant agglomerates were detected in the VBTMAC and MATMAC-containing latexes. In contrast, DADMAC-containing polymer particles were almost identical to styrene particles. Continuous nucleation took pla ce in the binary copolymerizations with VBTMAC and with MATMAC when using V 50 initiator. In the case of using KPS, VBTMAC-containing particles grew co ntinuously to a mean size much larger than the corresponding particles init iated by V50. The presence of acrylamide reduced DADMAC-containing particle size and diminished the agglomeration in the VBTMAC- and MATMAC-containing latexes. The results were interpreted via particle formation mechanism. (C ) 2000 John Wiley & Sons, Inc.