Thermal effects on the process of electropolymerization of pyrrole on mild steel

Polypyrrole films were electrosynthesized on mild steel with oxalic acid electrolyte at varying temperatures (25-65 degreesC), current density (0.5-6.0 mA/cm(2)) and pH (2.0, 4.0, 7.0 and 8.5). The concentrations of pyrrole and oxalic acid were maintained at 0.1 M each in galvanostatic experiments. The results show that lower temperatures favor the formation of polypyrrole on mild steel in acidic media. At higher temperature and lower current densities, oscillations in electrode potentials were observed. The film quality was poorest at pH 7.0, while very adherent and compact films were obtained in alkaline medium. Higher temperature in alkaline media favors the formation of better polypyrrole films in contrast with acidic media. (C) 2003 Elsevier B.V. All rights reserved.