ESR spectroscopy coupled with cyclic voltammetry was applied to invest
igate the influence of the doping anion concentration on paramagnetic
properties of polyaniline. After the electrochemical synthesis in acid
media, in situ ESR measurements were carried out during voltammetric
cycling of polyaniline in aqueous solutions containing tungstosilicic
acid and various amounts of HCl or HClO4. Changes in paramagnetic prop
erties of polyaniline depend on the concentration of doping anions. ES
R spectra and spin density-potential relationships suggest that the an
ion concentration is an important factor that has a considerable influ
ence on the formation of positive charges in the polymer chain.