On the improvement of stability of polypyrrole films in aqueous solutions

The stability of oxidised polypyrrole (PPy) doped with mobile anion (ClO4−) was studied in aqueous media. The influence of various components of the solution (dissolved O2, indifferent electrolyte, organic compounds) on the stability of PPy was characterised by cyclic voltammetry and electron-probe X-ray microanalysis (EPMA). It was established that dissolved O2 favours the PPy overoxidation—the rate determining process of the electrochemical corrosion. The high concentration of the indifferent electrolyte on the other hand enhances the stability of the PPy in aqueous solutions to an essential extent. The more effective inhibitors of the PPy corrosion are the surface-active anions (dodecyl sulfate) and polar aromatic compounds (benzyl alcohol, benzonitrile).