Electrochemical copolymerization of aniline with m-phenylenediamine

Electrochemical copolymerization of aniline with m-phenylenediamine (MPD) in sulfuric acid solution was investigated by cyclic voltammetry. At a high molar fraction of MPD (above 0.5), a strong inhibition of electropolymerization was found. Copolymerization was found to be possible only at low MPD to aniline molar ratio. The first redox couple of leucoemeraldine to emeraldine transition for a copolymer has a midpoint potential of 0.33 V versus AgAgCl and is shifted by about 0.2 V to the positive direction. The potential range, where an emeraldine form of copolymer exists, is narrower (0.37 V), as compared to polyaniline (0.65 V). A great current peak in the middle potential region was observed for a copolymer. Also, the memory effect of the bilayer structures of both polymers was studied.