Studies on Charge Trapping in Polypyrrole and Poly (N-methylpyrrole) Based Bilayers of Polymers with Opposite Ion-Exchange Properties

Charge trapping effects were studied for bilayers of conducting polymers: polypyrrole with immobilized poly (4-styrenesulfonate) ions/poly (N-methylpyrrole) doped with perchlorate ions (PPy(PSS)/PMPy) as well for PPy(PSS)/PPy (where PPy is polypyrrole doped with perchlorate ions). Trapping properties resulting from low cationic conductivity of the outer polymer layer were evaluated by comparing redox charges of oxidation/reduction of bilayers and single layers, obtained by voltammetric, chronoamperometric and chronopotentiometric method. The role of oxidation state of the polymer and electrolyte concentration was taken into consideration. Trapping effect was found to be enhanced for the outer polymer coating in the reduced state and for high electrolyte concentrations. The outer film was also found to prevent the inner coating from irreversible oxidation at positive potentials.