EFFECT OF CATIONS ON THE ELECTROCHEMICAL-BEHAVIOR OF P-TOLUENESULFONATE-DOPED POLYPYRROLE IN VARIOUS AQUEOUS-SOLUTIONS

The electrochemical behavior of p-toluenesulfonate-doped polypyrrole (PPy/TsO-) in aqueous solution was analyzed by cyclic voltammetry. These films were prepared by the electropolymerization of pyrrole in aqueous solutions. It was found that in aqueous solutions containing alkali metal ions (M+), the dopant anions (TsO-) in the PPy film could be exchanged relatively easily with electrolyte anions in aqueous solutions by potential sweeping. However, PPy/TsO- was electrochemically inactivated in aqueous solutions containing alkaline earth metal ions (M2+) or tetraalkylammonium ions (R4N+). It was found that the inactivation in aqueous solutions containing M2+ or R4N+ could not be explained simply by the hypothesis that these cations were not incorporated into PPy/TsO- during the reduction process because of their large ion size. It was speculated that the anisotropic molecular organization of PPy/TsO- might play a key role in its inactivation of PPy/TsO-.