Lipase-catalyzed modification of natural Sapium sebiferum oil-based polyol for synthesis of polyurethane with improved properties

Polyols are one of the dominant reactants in polyurethane (PU) synthesis. However, polyols from Sapium sebiferum oil prepared by epoxidation–hydroxylation have an inferiority of secondary alcohol groups and large non-functional branches. Their lower reactivity, which in turn limits the properties of the generated PU. In this study, the optimal reaction conditions for the synthesis of polyols with primary alcohol groups by lipase hydrolysis have been investigated by single factorial experiments and response surface methodology. The optimized conditions for lipase hydrolysis were identified as a molar ratio of 2.2 : 1, a reaction time of 11.2 h, and a temperature of 47.2 °C. The highest hydroxyl value of the obtained polyol with primary alcohol groups reached 211 mg KOH per g. Furthermore, a novel PU was successfully synthesized from the synthetic polyol and isophorone diisocyanate by an in situ polymerization method. The generated PU showed a glass transition temperature of 60.6 °C, an initial decomposition temperature of 307.2 °C, a tensile strength of 12.5 MPa, and a Young's modulus of 22.3 MPa. These good thermal and mechanical properties of the PU prepared from the modified polyol by lipase hydrolysis can be attributed to its greater number of chemical interactions and cross-linked networks.