The Protection Zone: A Long-Range Corrosion Protection Mechanism around Conducting Polymer Particles in Composite Coatings: Part II. PEDOT: PSS

PEDOT:PSS is most likely the intrinsically conducting polymer (ICP) with the most outstanding stability of its electrical properties. Thus it might be the ideal material when high-performance coatings for corrosion protection of metal products are of aim. The purpose of this work is to elucidate the protection against corrosion provided by PEDOT:PSS pigments when used as an additive in a conventional insulating coating, applied to iron and zinc. By means of dedicated model samples simulating ICP pigments in contact with the metal surface on a more macroscopic level, it was found that a "protection zone" is established in the vicinity of the ICP, hindering further coating delamination. Resistance against ionic transport at the coating/metal interface is of major significance for its endurance, as the functioning of the protection zone relies on galvanic polarization of the interface by the ICP. Scanning Kelvin Probe (SKP) has been employed to monitor the changes in corrosion potential, in order to evaluate and also compare the PEDOT:PSS performance to other ICPs available in the market, e.g. polyaniline and polypyrrole.