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

Abstract

Emulsifier-free emulsion binary copolymerizations of styrene with four types of quaternary ammonium cationic monomers, diallyldimethylammonium chloride (DADMAC), (3-(methacryloylamino) propyl) trimethyl ammonium chloride (MAPTAC), (2-methacryloyloxy) ethyl) trimethyl ammonium chloride (MATMAC), and vinylbenzyl trimethyl ammonium chloride (VBTMAC), were conducted at 70°C. 2, 2'-azobis (2-methylpropionamidine) dihydrochloride (V50) and potassium persulphate (KPS) were used as cationic and anionic initiator, respectively. Ternary copolymerizations were also carried out in the presence of acrylamide as a second comonomer. Monomer conversions were followed by ultraviolet spectroscopy and the polymer microparticles were characterized using 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 incorporation 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 particles. 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 place in the binary copolymerizations with VBTMAC and with MATMAC when using V50 initiator. In the case of using KPS, VBTMAC-containing particles grew continuously to a mean size much larger than the corresponding particles initiated 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. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1129–1140, 2000