ELECTROCHEMICAL POLYMERIZATION AND CHARACTERIZATION OF 2-VINYLTHIOPHENE AND SOME OF ITS DERIVATIVES

We have polymerized 2-vinylthiophene (2-VTh) anodically at a potential of 2.75 V vs Ag/Ag+ in acetonitrile solvent using tetrabutylammonium tetrafluoroborate as supporting electrolyte. Two products result: a se miconducting(10(-4) S/cm), dark coating on the electrode (polymer C) a nd a nonconducting precipitate from the anolyte solution (polymer B). Polymer B is spectroscopically similar to poly(2-vinylthiophene) (PVTh ) produced by bulk, benzoyl peroxide-initiated polymerization of 2-VTh (polymer A) except that it has a lower molecular weight (1.5 X 10(3) vs 1.9 x 10(4) for polymer A by SEC using polystyrene as standard). We propose that polymer C is PVTh in which ca. 25% of the thiophene ring s are cross-linked at the 5,5'-positions. Polymer C is interesting bec ause the limited conjugation length (two thienyl residues) leads to a conductivity on a par with other, more classical conducting polymers s uch as poly(N-methylpyrrole). We report the synthesis of other monomer s in our route toward elucidating the polymerization mechanism and str ucture of polymer C.