Electrochemical copolymerization of aniline and o-aminophenol

Poly(aniline-co-o-aminophenol) has been synthesized electrochemically in the solution consisting of 0.2 M aniline, 0.6 M H2SO4 and various concentrations of o-aminophenol. The copolymerization rate and the properties of the copolymer are strongly affected by the monomer concentration ratio. The copolymerization rate is about half of the electrochemical polymerization rate of aniline in the absence of o-aminophenol based on cyclic voltammetry. The cyclic voltammogram of the copolymer obtained at the optimum conditions is very similar to that of polyaniline in 0.2 M H2SO4 solution in the potential range -0.20 to 0.75 V (versus SCE), but a cathodic current plateau between 0.02 and 0.14 V on the cyclic voltammogram of the copolymer replaces a cathodic peak at 0.02 V on the cyclic voltammogram of polyaniline. The cyclic voltammograms of the copolymer in 0.3 M Na2SO4 solution of pH value from 5.0 to 9.6 were performed between -0.20 and 0.50 V at the scan rate of 60 mV/s. The results indicate that only a 29% decay of the electrochemical activity was observed when the copolymer was moved from pH 5.0 to 9.6. The electrochemical activity of poly(aniline-co-o-aininophenol) is about four times as high as that of polyaniline in 0.3 M Na2SO4 Solution of pH 5.0. A surprising result shows that two pairs of the redox peaks still appear on the cyclic voltammogram of the copolymer in the solution of pH 9.6 at the scan rate of 6 mV/s. In this case, its usable potential range is -0.20 to 0.62 V. The copolymer has a good stability and a high reversibility in the above solutions, and has a conductivity of 1.40 S/cm. The FT-IR spectrum and XPS spectrum of the copolymer are represented here. (C) 2004 Elsevier B.V. All rights reserved.