COMPARISON OF ELECTROCHEMICAL-BEHAVIOR OF HETEROPOLYACIDS IN SOLUTIONAND WHEN IMMOBILIZED IN A CONDUCTING POLYMER FILM

Doping-dedoping of poly-3-methylthiophene with heteropolyacid (HPA) an ions immobilized in its bulk is studied in water and acetonitrile by m eans of cyclic voltammetry. It is found that BPA anions permanently re tain background cations in their vicinity, and doping-dedoping is acco mpanied by ingress-egress of background anions. Investigation of the r edox behavior of BPA in solutions with different concentrations of sul furic acid in the polymer in the same solutions shows that acetonitril e and the polymer are identical media for HPA, and there is virtually no potential drop at the polymer/solution interface. At the same time, water and the polymer in water have different properties, and the pot ential drop contributes significantly to the total potential drop at t he electrode.