Electrochemical behaviour of polyaniline, poly(o-toluidine) and their copolymer in organic sulphonic acids

Abstract The effect of organic sulphonic acid on electrochemical, optical and conductivity properties of polyaniline (PA), poly(o-toluidine) (POT) and their copolymer polyaniline-copoly(o-toluidine) (PA-POT) thin films has been investigated. The films were synthesized electrochemically individually and then combinedly as binary copolymerization under cyclic voltammetric conditions in aqueous solution of sulphuric acid, p-toluene sulphonic acid, sulphamic acid and sulphosalicylic acid at room temperature. The films were electropolymerized in solution containing 0.1 M monomers and 1 M sulphuric acid or organic sulphonic acid as electrolyte by applying sequential linear potential scan rate 50 mV/s between −0.2 and 1.0 V versus Ag/AgCl electrode. The electrosynthesized films were characterized by cyclic voltammetry, UV-visible spectroscopy and conductivity measurement. It is observed that the UV-visible spectra are obtained ex situ in MSO and peaks for sulphuric acid, p-toluene sulphonic acid, sulphamic acid and sulphosalicylic acids are observed in conducting emerladine salt (ES) phase. In overall study, it was observed that all these three organic sulphonic acids as electrolyte shows higher conductivity than sulphuric acid; however, the highest conductivity is observed for p-toluene sulphonic acid as electrolyte as compared to sulphamic acid and sulphosalicylic acid, in homo- and copolymer films. A possible scheme of reaction mechanism for homo- and copolymer of aniline and toluidine has been suggested.