Improving the properties of carbonated soybean oil-based non-isocyanate polyhydroxyurethane networks: Copolymerization versus hybridization with epoxy resin

Carbonated soybean oil bio-based polyhydroxyurethanes (PHUs) produced without isocyanates often have inferior properties compared to their traditional isocyanate-based counterparts. To improve these properties, this study presents two strategies: copolymerization with other carbonated monomers and hybridization with epoxy monomers. Carbonated soybean oil (CSBO) and trimethylolpropane triglycidyl carbonate (TMPTC) were synthesized using the corresponding epoxidized monomers and carbon dioxide (CO₂). Various compositions polyhydroxyurethane (co)polymers were then prepared by an aminolysis reaction at 80 °C. CSBO/epoxy hybrids were also prepared by curing the samples with amines, first at room temperature and then at 80 °C. Fourier Transform Infrared Spectroscopy (FTIR) and gel content experiments showed that high conversion was achieved in both systems. Notably, the hybrid polymers exhibited a broader range of mechanical properties compared to the non-isocyanate polyurethane copolymers (NIPUs). Thus, the hybridization of CSBO with epoxy compounds offers a sustainable approach for the development of materials with different mechanical and barrier properties that can be customized for coating applications. While similar approaches have been individually studied, a direct comparison of their effectiveness within the same system remains unexplored.