EMULSIFIER-FREE EMULSION COPOLYMERIZATION OF STYRENE AND BUTYL ACRYLATE WITH CATIONIC COMONOMER

Emulsifier-free emulsion copolymerization of styrene (St) and butyl ac rylate (BA) in the presence of a cationic functional comonomer, N-dime thyl, N-butyl, N-ethyl methacrylate ammonium bromine (DBMA) was carrie d out using azobis (isobutyl-amidine hydrochloride) (AIBA) as an initi ator. The surface properties of particles were studied by testing the actual value of [GRAPHICS] on the surface of the particles and the sur face charge density. The copolymer particles were characterized using transmission electron microscopy (TEM). The effects of reaction temper ature, DBMA content, AIBA content, ionic strength, etc., on the conver sion of the monomer and the average diameter ((D) over bar w) and numb er (Np) of copolymer particles were investigated. Under constant ionic strength, the average diameter of copolymer particles ((D) over bar w ) decreased with increasing AIBA and DBMA concentrations and decreased with increasing reaction temperature also. Moreover, it increased wit h increasing St content in the monomer feeding. Under a constant conce ntration of the comonomer and initiator as well as the constant monome r composition, (D) over bar w shows a change process of increase-decre ase-increase in the ionic strength plot. The polymerization reaction r ate increased with increasing the DBMA content, AIBA content, and incr easing temperature. The surface charge properties of the particles wer e mainly decided by the DBMA content, AIBA content, ionic strength, et c. The methods of feeding the monomer affects the morphology, structur e, size, and surface charge density of the particles. (C) 1997 John Wi ley & Sons, Inc.