Polypyrrole electrogeneration at different potentials in acetonitrile and acetonitrile/water solutions

Abstract A comparative study of polypyrrole electrogeneration on platinum, by polarization at different potentials, in acetonitrile and acetonitrile + 2% of water content, was followed, through microgravimetric determination of the polymer grafted onto the electrode. The presence of water favours the polymerization at each potential. At high anodic overpotentials the polymer production decreases, when the potential rises, in both media. The simultaneous presence of three processes: electrochemical polymerization, homogeneous acid-catalyzed polymerization and water discharge, and the variation of its relative rate with the water content and the potential of polymerization is supported by experimental results. The proposed variation of these relative rates along the polarization times at high anodic overpotentials, allows to postulate the presence of a bilayer on these electrogenerated films.