Recyclable vitrimer epoxy coatings for durable protection

In this research, the synthesis and application of vitrimer epoxy coatings for long-term corrosion protection of metal surfaces are described. To that end, a polyamine curing agent based on vinylogous urethanes (VUs) was developed to add repairability, recyclability and recoatability to thermosetting materials. Thin films with excellent resistance to water penetration and damage could be obtained by combining the dynamic hardener with existing epoxy resins, resulting in good barrier properties. Various formulations were investigated yielding transparent coatings with durable corrosion protection, even after being scratched, exposed to saltwater, and subjected to steam condensation. Furthermore, stress-relaxation experiments revealed sufficient material flow at 150 °C, which could be significantly slowed down below 100 °C. Optical microscopy was used to demonstrate the healing ability of the vitrimer coatings, resulting in the restoration of barrier properties after scratching. The dynamic properties of the epoxy resin were used to recoat an aluminium plate as a proof of concept, demonstrating that the thin layer could be adhered to a surface again in its cured state. As a result, the service life of epoxy coatings and protected metals could be extended while maintaining excellent mechanical properties, opening the door to a wide range of potential applications such as marine coatings and concrete bonding.