EFFECT OF ELECTROLYTE SOLVENT ON THE CONDUCTIVITY AND STRUCTURE OF AS-PREPARED POLYPYRROLE FILMS

Eight kinds of solvents were used to study the effect of electrolyte s olvents on the conductivity and structure of polypyrrole (PPy) films p repared electrochemically in the electrolyte solutions. It was found t hat the conductivity of PPy films strongly depended on the donor numbe r (DN) of the electrolyte solvents used in their polymerization soluti ons. The conductivity increases with the decrease of the DN value of t he solution solvents. High conductivity films of 10(0)-10(2) S cm(-1) were prepared only in the solutions with the solvents of low or middle DN values. For the solvents with high DN such as dimethyl formamide ( DMF) and dimethyl sulfoxide (DMSO), the conductivity of the PPy films from their solutions were very low, ca. 10(-6) S cm(-1). The addition of some alcohol or ether in the polymerization solution resulted in a serious drop of the conductivity of the as-prepared PPy him. Absorptio n spectra and surface morphology of the as-prepared PPy films also sho w the dependence on the polymerization solvents. (C) 1997 Elsevier Sci ence Ltd.