On the development of polypyrrole coatings with self-healing properties for iron corrosion protection G. Paliwoda-Porebska a, * , M. Stratmann a , M. Rohwerder a , K. Potje-Kamloth b ,Y.Lu b , A.Z. Pich b , H.-J. Adler b a Max Planck Institute for Iron Research, Max-Planck-Strasse 1, 40237 D€ usseldorf, Germany b Institute of Macromolecular Chemistry and Textile Chemistry, Technical University Dresden, D-01062 Dresden, Germany Available online 12 September 2005 Abstract This paper presents studies on the efficacy and on the limits of polypyrrole (Ppy) doped witheitherMoO 2 4 or[PMo 12 O 40 ] 3 asself-healingcorrosionprotectingcoatings.Thekinetics ofthecathodicdelaminationwerestudiedbymeansoftheScanningKelvinProbe(SKP).This method, in combination with cyclic voltammetry, UV–visible spectroscopy (UV–vis) and X-ray photoelectron spectroscopy (XPS), shows a potential driven anion release from the Ppy coating that results in an inhibition of the corrosion process taking place in the defect. Thus, an intelligent release of inhibitor occurs only when the potential at the interface decreases. Inhibitor anions are released only due to an active defect. However, the release mechanism can be easily negatively affected by the presence of small cations and/or by too high pH values at the buried interface. Hence, such a self-healing coating has to be carefully designed in order to ensure an effective performance. Ó 2005 Elsevier Ltd. All rights reserved. 0010-938X/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.corsci.2005.05.057 * Corresponding author. Tel.: +49 211 6792538; fax: +49 211 6792218. E-mail address: paliwoda@mpie.de (G. Paliwoda-Porebska). Corrosion Science 47 (2005) 3216–3233 www.elsevier.com/locate/corsci