Redox Coupled Ion Exchange in Copolymers of Aniline with Aminobenzoic Acids

Copolymers of aniline and 2-aminobenzoic acid are prepared by chemical copolymerization. The copolymers are soluble in basic media and thin films are prepared, onto glassy carbon electrodes, by evaporation of the solutions. The modified electrodes show a voltammetric response, with two peaks, similar to polyaniline with two peaks. The dependence of both peak potentials on pH is similar to that of PANI, suggesting that proton expulsion is the mechanism of charge compensation on oxidation. The mechanism is confirmed by Probe Beam Deflection, which shows proton expulsion on oxidation. However, while polyaniline films exchange mainly anions at pH>0, poly(aniline-co-(2-aminobenzoic acid)) (p2ABA) film exchange protons up to pH 4.