Green Photocurable Vegetable Oil Biobased Thermoset Functionalized with Vanillin Methacrylate for Ultraviolet-Shielding Coatings

Abstract

Wood materials are adversely affected by UV irradiation due to their molecular structure containing lignin-based structures. This work aims to propose a sustainable, efficient, and scalable synthetic process leading to vanillin methacrylate (Vanillin MMA) and modified curable vegetable oil derived from epoxidized triacylglycerides. The approach uses methacrylic anhydride as an acyl donor for Vanillin MMA production, while the formed byproduct, methacrylic acid, is quantitatively isolated and used for vegetable oil modification. All synthesized products reached high yields of 94–97% and were characterized by NMR, MS, and FTIR characterization methods. Vanillin MMA exhibited an exceptionally high reactivity of 96.2 kJ/mol, while modified vegetable oil exhibited high thermal endurance, expressed by the heat-resistance index of 170.2 °C. The best-performing thermoset-forming system contained 30% Vanillin MMA, reaching a tensile modulus of 225.3 ± 5.7 MPa and a tensile strength of 15.1 ± 0.5 MPa. The flexural parameters resulted in a flexural modulus of 432.7 ± 7.9 MPa and a flexural strength of 16.9 ± 0.6 MPa. This thermoset coating achieved a 4B adhesion rating (based on the ASTM D3358 standard) and exhibited UV-shielding properties up to an irradiation wavelength of 357 nm.