ELECTROGENERATION OF CONDUCTING POLY(2,5-DI-(-2-THIENYL)-FURAN)

The electrochemical behaviour of 2,5-di-(-2-thienyl)-furan (SOS) on Pt has been studied in 0.2 M LiClO4 + acetonitrile + 0.25% (v/v) water s olutions by cyclic voltammetry, chronoamperometry and chronopotentiome try. The monomer oxidises at more positive potentials than 0.7 V vs. A g\AgCl giving a dark-blue film. The most reproducible film weights are obtained by flowing a constant current lower than 1.0 mA cm(-2). The resulting insoluble oxidised films are electroactive and electrochromi c. Their control voltammograms exhibit two redox processes attributed to polaronic and bipolaronic states, together with an intermediate red uction shoulder ascribed to radical cation pairs. Electropolymerisatio n kinetics have been followed by 'ex situ' ultramicrogravimetry, givin g a maximum productivity of 1.85 mg mC(-1). The oxidised poly(SOS) con tains polarons and electroinactive positive charges, both compensated with perchlorate counterions, The reduced poly(SOS) has been obtained in the same electrolyte bq applying a constant potential of 0 V to oxi dised films. A partial electrodissolution of films is observed during their reduction. The electroinactive charges present in the resulting reduced stale cause its insolubility in the medium. Densities, conduct ivities and solubilities in different organic solvents of both oxidise d and reduced poly(SOS) hale been determined. Short linear oligomers f ormed during SOS electropolymerisation have been detected in the satur ated solutions of reduced poly(SOS) by mass spectrometry-fast atom bom bardment. (C) 1998 Elsevier Science S.A. All rights reserved.