COMPARATIVE REACTIVITY OF THIOPHENE AND 3,4-(ETHYLENEDIOXY)THIOPHENE AS TERMINAL ELECTROPOLYMERIZABLE UNITS IN BIS-HETEROCYCLE ARYLENES

The monomers bis(2-thienyl)-9,9-didecylfluorene, BTDF, and ,4-(ethylen edioxy)thien-2-yl)-9,9-didecylfluorene, BEDOT-DF, have been synthesize d and electropolymerized to the corresponding conducting polymers. The potential for the electropolymerization of BTDF was found to be depen dent on the solvent composition. In CH2Cl2, polymer film deposition is achieved only at potentials higher than 1.3 V vs. Ag/Ag+, while in a 30/70 mixture of CH2Cl2/CH3CN the polymerization is efficient at 0.9 V . BEDOT-DF polymerizes at significantly lower potentials and more rapi dly than BTDF. The electron-donating alkoxy substituents of the EDOT u nits lead to stabilization of the cation radical intermediates allowin g the electropolymerization to proceed at 0.55 V. The neutral polymers are insoluble in common organic solvents and are stable to 300 degree s C under nitrogen. Upon oxidation, both polymers show two intragap tr ansitions at intermediate doping levels due to the formation of bipola ronic states and the oxidized polymers exhibit conductivities up to 10 (-4) S/cm. The redox-stimulated ion transport characteristics, studied by the electrochemical quartz crystal microbalance (EQCM) indicates t hat the electrolyte anions are the dominant mobile species. (C) 1997 J ohn Wiley & Sons, Inc.