One-step electrochemical process for the formation of poly(N-methylpyrrole) coatings on steel in different media

摘要

Poly(N-methylpyrrole) coatings have been successfully formed on steel by a one-step electrochemical process in different media. Electropolymerization was performed in aqueous medium with low monomer concentration and in a mixed aqueous/organic media with higher monomer concentrations. Ethanol ( EtOH) and N,N-dimethylformamide ( DMF) were chosen as the organic components of the mixed solvents and oxalic acid was used as the electrolyte. The effect of process parameters on the formation of poly(N-methylpyrrole) was systematically investigated. The composition and morphology of the coatings were also studied by elemental analysis, FT-IR and scanning electron microscopy (SEM). Our results reveal that the formation and properties of poly (N-methylpyrrole) coatings were all dependent on the solvent composition and other process parameters. The amount of poly(N-methylpyrrole) formed on steel increased with time and applied current for all the solvent-electrolyte systems. For the electropolymerization performed in distilled water-oxalic acid solution, the amount of polymer coatings formed decreased with increased electrolyte concentration. In contrast, the amount of polymer coatings formed on steel in distilled water:ethanol (1:1)-oxalic acid and distilled water:DMF (1:1)-oxalic acid systems, increased with increasing electrolyte concentration. By controlling the electrochemical parameters, smooth, uniform and strongly adherent coatings could be formed onto steel substrates. (C) 1998 Elsevier Science S.A. All rights reserved. [References: 20]