Spectroelectrochemistry of polyaniline at low concentrations of doping anions

Spectroelectrochemical techniques combined with cyclic voltammetry were applied to the investigations of polyaniline synthesized electrochemically in acid solutions. Voltammetric current response of the polymer films was measured in solutions containing tungstosilic acid (i.e. supporting electrolyte with anions too large to dope the polymer) and various amounts of HClO4. Simultaneously UV-VIS spectra were recorded. The concentration of small anions capable of doping the polymer was gradually increased. The nature of ionic species and their concentration significantly affect electrochemical and spectroelectrochemical properties of polyaniline.