One-step synthesis of novel renewable multi-functional linseed oil-based acrylate prepolymers and its application in UV-curable coatings

The use of renewable resources and their derivatives provides a green approach to synthesizing UV-curable raw materials, and it possesses many advantages, such as environmental protection and energy conservation. Linseed oil has become a research hotspot because of its high content of double bonds and biodegradability. In this study, boron trifluoride diethyl ether was used as a catalyst to successfully introduce acrylic acid into the double bond of linseed oil long chain. Therefore, the UV-curable acrylated linseed oil prepolymers (ALO) were prepared in one step. The characterizations of H-1 NMR and FT-IR were employed to verify the successful preparation of ALO. The viscosity of ALO was measured via rheological test, and it was turned out to be 803 mPa.s, indicating the prepolymers had a good processing property. The synthesis mechanism of ALO catalyzed by boron trifluoride diethyl ether was also proposed. Furthermore, different kinds of UV-curable films were prepared by mixing ALO with polyurethane acrylate resin (PUA-2665), trimethylolpropane triacrylate (TMPTA), and photoinitiator (PI 1173). As for the cured films, their thermal stability was investigated by thermogravimetric analysis (TGA), the dynamical mechanical properties were probed via dynamic mechanical analysis (DMA), and the mechanical properties were measured by tensile test. It was found that increasing TMPTA content promoted crosslinking density, leading to the improvement in thermal stability, storage modulus, and tensile strength of the cured films. Besides, they also exhibited excellent hardness, strong adhesion, and outstanding water (solvents) resistance on wood surface. Therefore, this study provides a novel one-step approach for the synthesis of UV-curable materials from vegetable oils, and the as-prepared high-performance films have potential for broad applications.