Self-healing protective coatings of polyvinyl butyral/polypyrrole-carbon black composite on carbon steel

Self-healing polyvinyl butyral (PVB) based organic coating formulations were prepared by incorporating polypyrrole-carbon black (PPyCB) composite as an inhibiting pigment. The redox properties and diffusion barrier nature of PPy imparted self-healing to the PVB/PPyCB composite coatings in aggressive environments. PPy induced the formation of a stable passive layer on the metal surface through the interaction of released dopant, from the organic sulfonic acid doped PPy with metal iron oxide. SEM images and Raman spectroscopy confirmed the formation of a protective passive layer on the metal surface. Furthermore, reduced PPy hindered the diffusion of water and oxygen through the coating. The addition of more conducting particles like graphene further enhanced the protective nature of the PVB/PPyCB composite coatings. This work demonstrates a possible application of conducting particles in enhancing the protective nature of organic coatings used widely in industry simply as a barrier coating.