Novel conducting polymer based composite coatings for corrosion protection of zinc

• The introduction of carbon black has solved the problem of Fermi-level misalignment.
• Carbon black supplies conductive pathways to activate more amount of PEDOT.
• The active charge of PEDOT is investigated by Scanning Kelvin Probe.
• Corrosion protection is achieved by the coating with the optimal concentration of carbon black.
• The delamination inhibition is due to the active polarization of the interface.

The application of conducting polymers on zinc tends to result in an electronically highly insulating interface leading even to Fermi-level misalignment at the polymer/metal interface. This makes the conducting polymers electrochemically inactive. To prevent this Fermi-level misalignment, carbon black was introduced as conductive spacer between the conducting polymer and the zinc into composite coatings of poly (3,4-ethylenedioxythiophene) (PEDOT) nanoparticles and a polyvinyl butyral (PVB) binder. It was found that the carbon black not only enabled electronic contact between zinc and the PEDOT, but also increased the amount of electrochemical available PEDOT in the coating, by supplying the necessary conductive pathways.