Cationic emulsions of triblock copolymer particles comprising a poly(n-butyl acrylate) (P(n)BA) central block and polystyrene (PS) outer blocks were synthesized by activator generated by electron transfer (AGET) atom transfer radical polymerization (ATRP). Difunctional ATRP initiator, ethylene bis(2-bromoisobutyrate) (EBBiB), was used as initiator to synthesize the ABA type poly(styrene-b-n-butyl acrylate-b-styrene) (PS-P(n)BA-PS) triblock copolymer. The effects of ligand and cationic surfactant on polymerizations were also discussed. Gel permeation chromatography (GPC) was used to characterize the molecular weight (M-n) and molecular weight distribution (MWD) of the resultant triblock copolymers. Particle size and particle size distribution of resulted latexes were characterized by dynamic light scattering (DLS). The resultant latexes showed good colloidal stability with average particle size around 100-300 nm in diameter. Glass transition temperature (T-g) of copolymers was studied by differential scanning calorimetry (DSC). (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 611-620