ELECTROPOLYMERIZATION MECHANISM OF HIGHLY CONDUCTIVE POLYANILINES ANDTHE UNIT MOLECULAR-STRUCTURE DETERMINED FROM A COULOMETRIC ANALYSIS OF THE ELECTROPOLYMERIZATION

Aniline and several aniline derivatives were electropolymerized with t wo different electrolysis modes: potential-sweep electrolysis and cons tant-current electrolysis. The voltammetric and chronopotentiometric r esponses during electropolymerization led to two polymerization mechan isms: radical-coupling polymerization and incorporation-oxidation poly merization. The latter polymerization proceeds as follows: 1 During th e initial stage a seed polymer with a low molecular weight is electrod eposited on the electrode surface. 2 The seed polymer is electro-oxidi zed and cation radicals are generated in the seed polymer. 3 The catio n radicals oxidize dissolved monomers and incorporate the oxidized mon omers. This polymerization was found to give highly conductive polyani lines. On the basis of the fact that the incorporation-oxidation polym erization obeyed Faraday's law, the electron number of the polymerizat ion reaction of aniline was analyzed coulometrically. The determined n umber implied that the polymeric backbone consisted mainly of benzenoi d structures, and that 2.77 anions were doped per an aniline unit.