Characterization of water-soluble externally HCl-doped conducting polyaniline

Water solubility in all pH region for externally HCl-doped conducting polyaniline (ED-SPAN) enables us to do its detail characterization by UV-VIS spectra, cyclic voltammogram, ESR spectra, and electrical conductivity in relation to the doping level. It was found that one free radical was produced in polyaniline backbone by the addition of one proton onto the imino-nitrogen. The electrical conductivity of ED-SPAN solid film remarkably increased with increasing free radical in polyaniline backbone because of remarkable increase of the hole mobility. Undoping of ED-SPAN solid occurred by heating at more than 40 degreesC. (C) 2002 Elsevier Science B.V. All rights reserved.