ELECTROCHEMICAL STUDY OF BILAYER CONDUCTING POLYMERS - POLYPYRROLE POLYANILINE SYSTEM

Cyclic voltammetric and electrochemical impedance spectroscopic studie s of polypyrrole (PPy)-polyaniline (PANI) bilayer conducting polymers were carried out in aqueous medium. The bilayers were prepared by elec trochemical polymerization of the corresponding monomers at a platinum electrode surface in 1 M HCI solution. Cyclic voltammograms show addi tive properties of the bilayer conducting polymers compared with the i ndividual polymers, Electrochemical impedance spectra revealed that th e overall responses were mainly dominated by the inner layers. It was found that the charge transfer resistance of PANI decreased markedly w hen PPy was the outer layer, which is indicative of mediated oxidation . In contrast, when PANI was used as the outer layer, the impedance sp ectra were similar to those of single PPy films. The electrochemical i mpedance responses were also characterized with respect to different p olarization potentials and thicknesses of the bilayers.