Synthesis, characterization and electrochromic properties of conducting copolymers of 3-[(3-thienylcarbonyl)oxy]-2,2-bis{[(3-thienylcarbonyl)oxy]}propyl 3-thiophene carboxylate with thiophene and pyrrole

3-[(3-Thienylcarbonyl)oxy]-2,2-bis{[(3-thienylcarbonyl)oxy]}propyl 3-thiophene carboxylate (TOTPT) was synthesized by the reaction of 3-thionylcarbonyl chloride with pentaerythritol, it was electrochemically polymerized with either thiophene or pyrrole by using tetrabutylammonium tetrafluoroborate (TBAFB) as the supporting electrolyte in acetonitrile (AN). Characterization of the resulting copolymers was carried out by FTIR spectroscopy, cyclic voltammetry, thermal gravimetry analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Electrical conductivities of the copolymers were measured by the four-probe technique. The electrochemically synthesized copolymer was found to be capable of switching between an orange reduced state and a greenish-blue color oxidized state, and has an electronic band gap of 1.95 eV. The copolymer exhibited a long-term switching stability up to 400 double switches. (C) 2004 Elsevier B.V. All rights reserved.