Raman spectroscopy for the study of polyaniline

Raman spectroscopy (RS) is generally used for a qualitative discrimination of the different polyaniline (PANI) forms. The theoretical assignment of the main bands was done satisfactorily in the case of insulating forms, but it is not the same in the case of conductive forms. A new band at ≈ 1330 cm−1 empirically observed during protonation is assumed to correspond to the stretching of C-N bonds. This band, as well as the C=N stretching one must be modified in function of the polaron delocalization. The electropolymerization of PANI allows to form films with variable protonation and/or oxidation levels; the corresponding modifications of the Raman spectra can be scrutinized to progress in the interpretation of these spectra, in order to use this technique for a better analysis of conductive polymers.