Vibrational analysis of the reduced form of polyaniline: the leucoemeraldine base

Abstract Extensive studies have been carried out on the different forms of polyaniline. In this paper, we present a study of the vibrational properties of the leucoemeraldine base, the reduced form of polyaniline. Infrared absorption and resonant Raman scattering (RRS) spectra are presented for the polymer, together with those obtained in model compounds such as diphenylamine and N , N ′-diphenyl-1,4-phenylenediamine. The Raman spectrum of the leucoemeraldine base exhibits mainly bands at 1181, 1219, 1597 and 1618 cm −1 . By the use of a valence-force-field model, we have assigned these vibrational modes, including those of the model compounds. Calculations are in rather good agreement with previous assignments and the main force constants, which are determined from the fit of the experimental IR and Raman bands, are physically reasonable compared to what is found in other polymers.