UV light triggered self-healing of green epoxy coatings

Abstract

Abstract Numerous studies have been carried out globally to develop polymer coatings that could protect the underlying metal substrates from corrosion. Among these approaches, self-healing bio-based epoxy coating plays a promising role in corrosion protection. In the present study, a dual container self-healing coating system was developed from bio-based epoxy resin, halloysite nanotubes and silica nanoparticles. The halloysite nanotubes (HNTs) were filled with bio-based epoxy resin by vacuum infiltration technique and the silica nanoparticles were modified with a UV initiator by simple mixing. Later the filled halloysite nanotubes and modified silica nanoparticles were mixed with pure bio-based epoxy resin and hardener and cured to obtain self-healing composites. During the scratch/damage of the epoxy coating, the halloysite nanotube ruptures and the bio-based epoxy resin stored inside the nanotube fills the scratch and comes in contact with UV initiator immobilised on the silica nanoparticles, initiating the curing reaction. At 40\xa0wt% of encapsulated HNTs, the scratch on the bio-based epoxy surface is found to undergo complete self-healing in the presence of sunlight. Overall, the composites showed an increased UV-shielding ability, improved thermal stability, and good transparency. Therefore, the developed bio-based epoxy composite is a viable self-healing coating for metals.