An electrochemical study of two self-dopable water-soluble aniline derivatives: electrochemical deposition of copolymers.

An electrochemical study of two water-soluble aniline derivatives, N-(3-sulfopropyl) aniline (AnPS) and N-(3-sulfopropyl) p-aminodiphenylamine (DAnPS), in aqueous acidic electrolytic solutions containing different kinds of doping anions (Cl (-), SO(4) (2-), and ClO(4) (-)) was carried out. At sufficiently high anodic potential, the sulfonated aniline derivatives undergo oxidation processes yielding cation-radical and dimer intermediates, but no polymer deposition was observed on the working electrode surface. Experimental results showed that both aniline derivatives are electroactive compounds exhibiting redox behaviour in the range of potential of -0.2 V-1.6 V. Due to the self-doping effect induced by sulfonic groups, AnPS and DAnPS compounds have good electroactivity even in neat water solution. By adding a small amount of aniline into electrolytic system, thin layers of copolymers were deposited on the working electrode surface. The copolymer layers formed on the electrodes show a highly orientational and positional order, confirmed by AFM and XRD spectroscopic techniques. During the anodic oxidation processes some distinct colour changes were observed.