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 solvents on the conductivity and structure of polypyrrole (PPy) films prepared electrochemically in the electrolyte solutions. It was found that the conductivity of PPy films strongly depended on the donor number (DN) of the electrolyte solvents used in their polymerization solutions. The conductivity increases with the decrease of the DN value of the 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. Absorption spectra and surface morphology of the as-prepared PPy films also show the dependence on the polymerization solvents. (C) 1997 Elsevier Science Ltd.