Polyaniline/poly(methylmethacrylate) blends for corrosion protection: The effect of passivating dopants on different metals

This paper describes the mechanism concerning active corrosion protection of metals using different conducting blends, formed by doped polyaniline (PANI) and poly(methylmethacrylate) (PMMA). Electrochemical and spectroscopic techniques are used to investigate the influence of two different dopants of PANI on the anticorrosion performance for different metals: camphorsulfonic (HCSA) and phenylphosphonic acids (HPPA). Moreover, it was also carried out a structural characterization of conducting blends and the analysis of the passive films formed as a consequence of the redox reaction between PANI and the metal substrates. In all the metal/blend systems, a potential shift to more positive values than the potential of uncoated metals in acid solution is observed, indicating the protection of the metal substrate. Moreover, Raman microscopy technique showed a clear diminution of the oxidation number of the conducting polymer in the blends and also the presence of a second passive layer formed by counter ions released from PANI and different metal cations.