Oxidized model compounds of polyaniline studied by resonance Raman spectroscopy

The emeraldine salt structure, the only conducting form of polyaniline is not well-known. This is why, we have carried out resonance Raman spectra (RRS) on one of these models compounds oxidized electrochemically in-situ in order to elucidate the electronic structure of this polymer partially oxidized in an acidic medium. A phenyl end-capped dimer of polyaniline, N,N′ diphenyl-p-phenylenediamine (named PCD), was selected. This dimer has been electrochemically oxidized in acetonitrile containing 0,2 M tetrabutylammonium tetrafluoroborate as ground salt and 0.1 M diphenyl phosphate as acid. The choice of laser excitation wavelength was fixed by UV-Vis absorption measurements on PCD in the acidic medium. Numerous similarities between emeraldine salt and radical species created were observed and are discussed in this paper.