SOLVENT EFFECTS ON THE POLYMERIZATION KINETICS OF SOME ALPHA-SILYLATED THIOPHENE OLIGOMERS - SPECIAL INFLUENCE OF THE ALPHA-SILYL GROUP

Oxidation of several silylthiophene oligomers has been studied in apro tic solvents by cyclic voltammetry. Reversible voltammograms were obta ined at low or very high scan rates depending on the nature of the oli gomer (from 0.05 V s(-1) for 5,5'''-bis(trimethylsilyl)quaterthiophene to 25000 V s(-1) for 5-(trimethylsilyl)bithiophene in acetonitrile). The lifetimes of the electrogenerated radical cation were estimated fr om the appearance of the reversibility of the cyclic voltammogram. The reactivity of silyloligothiophene was found to change to a large exte nt with the nature of the solvent (two orders of magnitude from dichlo romethane to acetonitrile). These results suggest the intervention of the desilylation reaction in the kinetically determining step of the p olymerization process.