ELECTROCHEMICAL OXIDATION OF 2,5-DI-(-2-THIENYL)-PYRROLE IN ACETONITRILE - CATHODIC STRIPPING OF THE ELECTROGENERATED CONDUCTING POLYMER

The electrochemical behaviour of 2,5-di-(-2-thienyl)-pyrrole was studi ed by cyclic voltammetry, chronoamperometry and chronopotentiometry. T he monomer oxidation-polymerization takes place on platinum at potenti als more positive than 0.3 V vs SCE. At higher potentials, the oxidati on processes in the polymer layer seem to control the generation of th e polymer and the polymer properties. Polymer films electrogenerated a t potentials lower than 0.7 V are insoluble in LiClO4 + acetonitrile s olutions. When the polymer film is reduced electrochemically, it becom es soluble. The solubility is a faradaic process: the weight of electr ochemically solubilized polymer is proportional to the cathodic electr ical charge consumed. The linearity of the process was proved using di fferent cathodic current densities. The polymer oxidation at potential s more positive than 1 V promotes the insolubility of the polymer, pro bably by a crosslinking process. The reduction of the polymer at poten tials below 0.2 V promotes stripping of the polymer from the electrode . The polymer structure was studied by Fourier transform IR reflectanc e. The UV-Vis study of the oxidized and reduced polymer in solution le d to the band structure and showed the self-reduction of the dissolved polymer.