Concomitant Processes in the Redox Switching of Polyaniline

It is shown for the first time that the redox switching of polyaniline (PANI) under voltammetric conditions is accompanied by the following processes: oxidation of PANI by atmospheric oxygen in the range of low potentials (E < 0.2 V); reduction with addition of aniline (post-polymerization) at E > 0.2(5) V, which in the range 0.2(5) < E < 0.5 V compensates entirely for the oxidation over the timescale of the cyclic voltammogram. These processes determine: (a) the existence of the emeraldine (conducting) state in a potential window (instead of at a defined potential); (b) the fundamental asymmetry in the redox behaviour of PANI; (c) the difference in the rates of the oxidation and reduction transients and (d) the dependence of the electrochemical activity of PANI on the pH of the medium.