Efficient and eco-friendly UV-cured polyurethane coating: Harnessing thiol-yne systems for corrosion protection

The UV-curable coatings have received significant attention from researchers due to their excellent advantages in corrosion protection. However, there has not been much effort made to investigate the UV-curable thiol-yne system. This project aims to prepare effective and environmentally-friendly polyurethane coatings capable of being cured by UV light using thiol-yne systems. Utilizing the chain extender derived from the glycolysis of PET, the bis(2-hydroxyethyl) terephthalate (BHET) as a glycolysis product was synthesized via the glycolysis reaction. Polyurethanes (PUYNE: yne-terminated polyurethanes and PUSH: thiol-terminatted polyurethanes) were synthesized by utilizing BHET, and by altering the quantity of the BHET, and PUX coatings were formed upon exposure to UV light. The impact of PUYNE molecular weight and the resulting amount of thiol-yne crosslinking on mechanical and thermal properties were evaluated, and corrosion resistance was examined with electrochemical impedance spectroscopy (EIS). PUX1, which had the lowest molecular weight and the highest number of thioether bonds, exhibited the superior corrosion resistance properties so that after 8 weeks of immersion in saline solution, the impedance modulus at 0.01 Hz was 1.43×108 Ω.cm2. This study provides insight into the application of thiol-yne systems in forming UV-cured coatings and their protective role in preventing corrosion.