Electrooxidation of aromatics to polymer films

This report describes the electrochemical preparation and properties of polyaniline films prepared on a bare platinum electrode and on electrodes precoated with a thin film of inert polymer. Films were prepared and studied in several aqueous acid electrolytes including sulfuric, hydrochloric, nitric, trifluoromethylsulfonic, hydrofluoric and trifluoroacetic acid. It is observed that both the concentration and nature of the acid influence the kinetics of the switching reaction. In the more acidic solutions, the reaction has at dependence and depends on the movement of a front across the thickness of the film. In the less acidic solutions, the reaction has a t1/2 dependence and depends on the diffusion of ions in the film. The same response is observed for the oxidation and the reduction reaction. Polyaniline is also electroactive in other various nonaqueous solvents, such as, alcohols, acetic acid and acetonitrile, and voltammograms with well defined waves result when solution contains both organic salt and protic acid. Polyaniline was also prepared on a platinum electrode coated with an inert polymer film such as polymethylmethacrylate (PMMA). The resulting polymer blend is electroactive and the switching reaction is slower than for polyaniline formed on a bare platinum electrode. Finally, a brief description is given of electroactive polyaniline films which can be prepared by polymerization of aniline in a glow discharge. Copyright © 1987 Hüthig & Wepf Verlag