Electrochemical and Raman spectroscopic studies of electrosynthesized copolymers and bilayer structures of polyaniline and poly(o-phenylenediamine)

Copolymers and bilayer structures consisting of polyaniline (PANI) and poly(o-phenylenediamine) (POPD) were electrosynthesized on a platinum electrode. It was shown that the ‘first cycle effect’ observed on PANI-coated electrodes, i.e. that the oxidation current passed in the first cycle is larger than in subsequent cycles, is enhanced to a great extent when an additional POPD layer is placed between the electrode and the PANI layer. This enhancement is discussed in terms of anion consumption, taking place during redox processes of both polymers. Raman spectroelectrochemical investigations of POPD and bilayer structures show a strong Raman band at 1415 cm−1, which is present in POPD-containing layers. It shows an intensity maximum in a potential region wherein POPD redox transformations proceed, and originates probably from a half-oxidized state of POPD. This confirms a two-step oxidation mechanism of the latter polymer.