Green self-healing coating for corrosion protection of zinc

A new study decribes polypyrrole nanocapsules bearing quaternised alkyl pyridine for a corrosion protection coating for zinc.

 A coating with polypyrrole nanocapsules bearing quaternised alkyl can protect zinc.  Image source: fablok - (symbol image).

During the study, fist of all the corrosion rate of coated zinc in a 3.5 wt. % NaCl electrolyte solution was studied. Epoxy resin coatings loaded with polypyrrole/dodecyl benzene sulfonate/quaternised alkyl pyridine and polypyrrole/dodecyl benzene sulfonate nanocapsules were compared to a non-loaded resin coating.

The nanocapsule-loaded coatings exhibited improved self-healing corrosion inhibitory properties. The self-healing properties were characterised by swelling ratio, electrochemical impedance spectroscopy, tafel polarisation, open circuit potential (OCP), FESEM, and optical microscopic imaging. The results over a 50-day time interval confirmed the stable self-healing behavior with the corrosion protection of 99.87 % in the scratched coating, containing polypyrrole/dodecyl benzene sulfonate/quaternised alkyl pyridine nanocapsule.

Potentially synergistic effect

The controlled release of quaternised alkyl pyridine was monitored by fluorescence emission spectroscopy and fluorescence microscopic imaging. A potentially synergistic effect in corrosion protection and self-healing is expected to have happened by polypyrrole inhibitory properties, the formation of Zn(DBS)2 complex, and the physical adsorption of quaternised alkyl pyridine on the metal surface.

The study has been published in Progress in Organic Coatings, Volume 147, October 2020.

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