Stable functional cationic latices were prepared by emulsion-free emulsion copolymerization of styrene (St) and butyl-acrylate (BA) with 1-butyl-4-vinyl-pyridinium bromide (qBVPBr) as functional comonomer and azobis(isobutyramidine hydrochloride) (AIBA) as initiator at (70 +/-1)degrees C The influences of the reaction temperature, the initiator concentration, and comonomer concentration on the polymerization conversion (x %), polymerization rate (R-p) of poly(St/BA/qBVPBr) emulsions were investigated. The results indicated that x % and R-p increase with increasing qBVPBr or AIBA concentration, and temperature, and R-p can be expressed as R-p = K-p [AI-BA](0.73)[qBVPBr](0.08) (r(AIBA) = 0.9968; r(qBVPBr) = 0.9946, both r(AIBA) and r(qBVPBr) are linear correlation coefficient) and the apparent activation energy (E-a) is 47.89 kJ mol(-1). In the absence of emulsifier condition, curves of R-P versus reaction time obeyed the typical behavior characterized by Intervals I, II, and III as similar conventional emulsion polymerization. The formation and growth of poly(St/BA/qBVPBr) latex particles has been studied at different reaction times. The results indicate that N-p decrease gradually with time at the early polymerization stages and then reach a constant value after about 20%, conversion, but D-p by photon correlation spectroscopy grow continuously as all polymerization proceed. Both the particle size distribution and molecular weight distribution curves are of bimodal size distribution and indicate the participation of at least two mechanisms of particle formation, namely, homogeneous nucleation in the aqueous phase and micellar nucleation. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 2092-2098, 2009