Polyaniline, poly(aniline-co-4,4'-diaminodiphenylsulfone), and poly(4,4'-diaminodiphenylsulfone) were synthesized by ammonium peroxydisulfate oxidation and characterized by a number of techniques, including infrared spectroscopy, ultraviolet-visible absorption spectroscopy, H-1-NMR, thermogravimetric analysis, and differential scanning calorimetry. These copolymers had enhanced solubility in common organic solvents in comparison with polyaniline. The conductivities of the HCl-doped polymers ranged from 1 S cm(-1) for polyaniline to 10(-8) S cm(-1) for poly(4,4'-diaminodiphenylsulfone). The copolymer compositions showed that block copolymers of 4,4'diaminodiphenylsulfone (r(1) > 1) and aniline (r(2) < 1) formed and that the reactivity of 4,4'-diaminodiphenylsulfone was greater than that of aniline. The results were explained by the effect of the -SO2- group present in the polymer structure. (C) 2003 Wiley Periodicals, Inc.