Development of an Innovative Biobased UV Coating Synthesized from Acrylated Epoxidized Soybean Oil and Poly(octamethylene maleate (anhydride) citrate)

Acrylated epoxidized soybean oil (AESO) as a biobased curable oligomer with different functionalities and poly(octamethylene maleate (anhydride) citrate) (POMaC) as a biobased unsaturated monomer with polar groups were both synthesized. The chemical structures of POMaC and AESO were confirmed by Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance (1H NMR) spectroscopies. Then POMaC was used to copolymerize with AESO to prepare a series of high biobased content coatings via an ultraviolet (UV) curing process. The thermomechanical properties and coating properties in terms of hardness, adhesion, and water contact angle (WCA) were also investigated. The results show that AESO/POMaC coating has improved thermal stability and improved hardness compared with bare AESO-based coating. Furthermore, the adhesion of AESO/POMaC was markedly improved by 290%. The mechanism of adhesion enhancement was investigated by the combination of experiment and simulation. The decreased water contact angle represents the enhanced surface free energy of AESO/POMaC, and the molecular dynamics simulation results show higher binding energy and more hydrogen bonds of AESO/POMaC with the substrate. These results confirm that the polar groups and high soft-segment content of AESO/POMaC coating could strongly interact with the surface and could provide more adhesion contact area, which is responsible for the increased adhesion under dry and wet conditions. This work illustrates the potential of POMaC, as a renewable alternative component for the development of high-performance AESO-based green coatings in the future.