Synthesis of green hybrid materials using starch and non-isocyanate polyurethanes

Green and environment-friendly polymers with comparable thermal and mechanical performance can be suitable alternatives of synthetic polymers. This paper documents the synthesis of crystallizable polyhydroxyurethanes (PHUs) through a facile, non-isocyanate and catalyst-free route with step growth polymerization of ethylene carbonate and three different diamines (1,2-ethanediamine, 1,4-butanediamine and 1,6-hexanediamine). The PHU monomers were interacted with gelatinized starch (HAGS) to synthesize HAGS/PHU hybrid materials. Both PHU monomers and hybrid materials were characterized by FT-IR, ¹H NMR, ¹³C NMR, DSC and XRD. Hydroxyl groups of HAGS and PHUs were found to predominantly contribute to the intermolecular hydrogen bonding. The films produced using HAGS/PHU hybrid materials exhibited tuneable mechanical properties with tensile strength ranging between 1.7 MPa and 3.2 MPa and a breaking strain varying between 45% and 121%. These findings underscore the potential of non-isocyanate polyurethanes as environmentally sustainable materials and provide facile route for synthesis of HAGS/PHU hybrid materials.