Electrochemistry of conductive polymers .20. Early stages of aniline polymerization studied by spectroelectrochemical and rotating ring disk electrode techniques

Early stages of aniline oxidation have been studied employing spectroelectrochemical and rotating ring disk electrode experiments in solutions of low (2 mM) and high (100 mM) aniline concentrations in 1 M H2SO4. Results indicate that a large amount of the tail-to-tail dimer, benzidine, is produced in the initial stage of aniline oxidation, which is followed by the generation of the head-to-tail dimer, N-phenyl-p-phenylene diamine (PPD), as well as oligomers in solutions of high aniline concentrations The intermediate species hare been identified hg spectroelectrochemical and rotating ring electrode (RRDE) voltammetry experiments, and the relative amount of dimeric products has been estimated from the RRDE voltammograms. Evidence for the presence of a nascent species produced upon oxidation of aniline is presented from the RRDE experiments.