Polyaniline nanotubules-anion effect on conformation and oxidation state of polyaniline studied by Raman spectroscopy

Polyaniline nanotubules have been obtained by using both chemical or electrochemical synthesis. The effect of the polymerization bath composition on morphology and molecular structure of nanotubules has been studied by means of scanning electron microscopy (SEM) and Raman microspectroscopy. As revealed by SEM, electrochemically obtained tubes are more rigid and uniform comparing with those obtained by chemical synthesis. Raman depth profiles across the template membrane containing nanotubules were studied. Most significant differences between Raman spectra of the variously obtained nanotubules are introduced by the kind of acid present in the polymerization bath. In particular, perchloric acid promotes stretched-planar conformation and the polaronic structure of polyaniline in tubes, while hydrochloric acid favors twisted (or random) conformation and quinoid structures. (C) 2003 Elsevier B.V. All rights reserved.