SELF-DOPED POLYANILINES ELECTROCHEMICALLY ACTIVE IN NEUTRAL AND BASIC AQUEOUS-SOLUTIONS - ELECTROPOLYMERIZATION OF SUBSTITUTED ANILINES

To obtain polyaniline (PAn) films that are electrochemically active in neutral aqueous solutions, the electropolymerization of three substituted anilines (anthranilic acid, m-aminobenzoic acid and m-aminobenzenesulphonic acid) was studied. Cyclic voltammograms of copolymers of substituted and unsubstituted anilines (monomer ratio 1:1) showed redox activity in neutral and basic aqueous solutions up to pH 10. The decrease in redox activity occurred more than 5 pH units higher than in the case of the usual PAn. Among aniline derivatives taken for the synthesis, a meta position and a sulpho group were preferable to produce the optimal self-doped PAn. A new redox couple in the negative potential region (E(o') = -0.24 V, Ag/AgCl, pH = 1) was observed. Self-doped polyanilines were also investigated by means of impedance spectroscopy.