The N-substituted polyaniline (PANi) was synthesized by incorporation of bromine-terminated polystyrene (PS-Br) onto the emeraldine form of polyaniline. End brominated polystyrene was synthesized by atom transfer radical polymerization (ATRP) technique and then deprotonated polyaniline was reacted with PS-Br to prepare PS-grafted PANi (PS-g-PANi) copolymer through N-grafting reaction. The degree of N-grafting can be controlled by adjusting the molar feed ratio of PS-Br to the number of repeat units of PANi. The microstructure and compositions of the PS-g-PANi copolymers with different degrees of N-substitution were characterized by FT-IR, elemental analysis, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The cyclicvoltammetry shows that the electroactivity of N-substituted PANi is strongly dependent on the degree of N-grafting. The solubility of PS-g-PANi copolymers in common organic solvents such as tetrahydrofuran and chloroform was improved by increasing the degree of N-grafting, and also the samples are partially soluble in xylene. (c) 2007 Wiley Periodicals, Inc.