Journal of Polymer Science Part A: Polymer Chemistry, Vol.35, No.17, 3627-3636, 1997
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 bis(3,4-(ethylenedioxy)thien-2-yl)-9,9-didecylfluorene, BEDOT-DF, have been synthesized and electropolymerized to the corresponding conducting polymers. The potential for the electropolymerization of BTDF was found to be dependent 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 rapidly than BTDF. The electron-donating alkoxy substituents of the EDOT units lead to stabilization of the cation radical intermediates allowing the electropolymerization to proceed at 0.55 V. The neutral polymers are insoluble in common organic solvents and are stable to 300 degrees C under nitrogen. Upon oxidation, both polymers show two intragap transitions at intermediate doping levels due to the formation of bipolaronic 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 that the electrolyte anions are the dominant mobile species.
Keywords:CONDUCTING POLYMERS;ELECTROCHEMICAL PROPERTIES;ELECTROCHROMIC PROPERTIES;ELECTRICAL-CONDUCTIVITY;ELECTRONIC-PROPERTIES;REPEAT UNITS;PHENYLENE;PYRROLE;FILMS;ELECTROOXIDATION