Novel long chain unsaturated diisocyanate from fatty acid: Synthesis, characterization, and application in bio-based polyurethane

摘要

A novel long chain linear unsaturated terminal diisocyanate, 1,16-diisocyanatohexadec-8-ene (HDEDI) was synthesized from oleic acid via Curtius rearrangement. Its chemical structure was identified by FTIR, ~1H NMR, ~(13)C NMR, and HRMS. This diisocyanate was used as a starting material for the preparation of entirely bio-based polyurethanes (PUs) by reacting it with canola diol and canola polyol, respectively. The physical properties and crystalline structure of the PUs prepared from this diisocyanate were compared to their counterparts prepared from similar fatty acid-derived diisocyanate, 1,7-heptamethylene diisocyanate (HPMDI). The HDEDI based PUs demonstrated various different properties compared to those of HPMDI based PUs. For example, HDEDI based PUs exhibited a triclinic crystal form; whereas HPMDI based PUs exhibited a hexagonal crystal lattice. In addition, canola polyol-HDEDI PU demonstrated a higher tensile strength at break than that of canola polyolHPMDI, attributed to the higher degree of hydrogen bonding associated with the former sample. Nevertheless, lower Young's modulus and higher elongation in canola polyol-HDEDI PU were obtained because of the flexibility of the long chain introduced by the HDEDI diisocyanate.