Synthesis of Eugenol-Based Polyols via Thiol–Ene Click Reaction and High-Performance Thermosetting Polyurethane Therefrom

The thiol–ene click reaction to prepare biobased polyols is a strategy to promote the green and environmental protection of polyurethane. The excessive usage of thiol and low conversion of carbon–carbon double bonds (C═C) would severely limit the properties of polyurethane (PU). In this work, a set of eugenol-based polyols were prepared via the thiol–ene click reaction. Interestingly, the conversion of the C═C was nearly 100% at the eugenol and various thiol compounds (—SH) in a stoichiometric ratio without excess of —SH. Then, the prepared polyols were reacted with diphenylmethane-diisocyanate (MDI), followed by a series of structure-adjustable thermosetting polyurethane networks with colorless transparency, high glass transition temperature (Tg), and good mechanical properties being obtained. In particular, the tensile strength was up to 54.88 MPa, and Tg can be adjusted from 36.45 to 77.21 °C. Moreover, it is revealed that the compounds with an allyl structure are conducive to the efficient click reaction, and its application in PU can be greatly extended.