Electropreparation and electrochemical stability of polythiophenes in acetonitrile containing anhydrous HBF4

The electrooxidation behavior of thiophene and 8-methylthiophene on a Pt su rface in an acetonitrile + tetrabutylammonium tetrafluoroborate solution we re investigated. The electropolymerization of these monomers was studied in neutral, acidic, and basic media. The effects of thiophene concentration a nd the added acid were elucidated. The polythiophene and poly(3-methylthiop hene) films formed were characterized by their cyclic voltammograms in a bl ank solution and dry conductivities were measured. Electrochemical properti es of these polymers in the same medium were investigated in the absence an d in the presence of added anhydrous acid and base. The behavior of the fre shly prepared films was compared with that which lost its electroactivity a s a result of electrooxidation using cyclic voltammetry, controlled potenti al coulometry, and FTIR spectroscopy. The mechanisms related to the formati on of the polymers and their electroactivity loss were proposed. (C) 2000 J ohn Wiley & Sons, Inc.