Synthesis of a Novel Type of Electrochemically Doped Vinyl Polymer Containing Pendant Terthiophene and Its Electrical and Electrochromic Properties

Abstract

A novel kind of electrochemically doped poly(5-vinyl-2,2':5',2''-terthiophene) has been prepared by electrochemical doping of poly(5-vinyl-2,2':5',2''-terthiophene) and by electrolytic polymerization of 5-vinyl-2,2':5',2''-terthiophene in the presence of tetra-n-butylammonium perchlorate as a supporting electrolyte. The electrochemically doped poly(5-vinyl-2,2':5',2''-terthiophene), obtained as bluish purple lustrous films, is identified as a partially oxidized radical-cation salt with ClO 4 - as a dopant, having a partially cross-linked structure due to the coupling reaction of the radical cation of the pendant terthiophene moiety. The polymer with a degree of doping of 45% exhibits a room-temperature conductivity of 2×10 -8 S cm -1 with an activation energy of 0.5 eV. The polymer undergoes a reversible clear color change from bluish purple to pale yellowish orange and vice versa on electrochemical dedoping and doping and functions as a novel class of potential electrochromic material