Electro-oxidation of polyaniline in the presence of electronic acceptors and the magnetic properties of the resulting polyaniline

Reduced polyaniline (PANI) exhibits a Nernstian response to dissolved electronic acceptors chloranil (CHR) with a linear relationship between electrode potential and the logarithm of the concentration of the acceptors (logC) with the positive slope. On the other hand, in the cyclic voltammograms showing the redox activities of PANI on the electrode surface, the peak potential is proportional to logC with the negative slope. These linear relationships imply an electronic interaction between PANI and the acceptors. The comparison of the PANIs before and after the contact to the acceptors in the UV-visible absorption spectra and elemental composition revealed that the interaction not only transforms the electronic state of PANI, but also incorporates the acceptors. Both measurements of electron spin resonance (ESR) and magnetic susceptibility demonstrate that the incorporation magnetized PANI. Although the PANI incorporating CHR shows no ferromagnetism, it possesses paramagnetic properties, which do not obey the Curie-Weiss law. In addition, further analysis of the ESR spectra reveals that the radical species are stabilized in the polymer chains.