Optical and vibrational spectra of sols/solutions of polyaniline: water as secondary dopant

The nature of polyaniline (2A or 2S form) dissolved in concentrated sulfuric and methanesulfonic acid has been investigated by (UV-Vis-NIR) optical absorption and Raman scattering using various exciting laser lines. Two different palaronic species have been evidenced and selectively analysed, using 15N labelled and perdeuterated ring derivatives. Addition of water induces formation of 2S-like materials, probably forming a sol and not a true solution. The achievement of the metallic state seems to be related to the ordering of the chains interacted with water, oxonium ions and anions.