Abstract:We report an efficient and green approach to synthesize a linear castor oil-based polyurethane (CPU) without using any solvent or catalyst. Diol monomers were first synthesized by the aminolysis reaction between castor oil and diamines; this was accomplished within 6 h at 130 • C. Polymerization of the diols and isocyanate was further confirmed by Fourier transform infrared (FTIR), 1 H-nuclear magnetic resonance ( 1 H-NMR), and gel permeation chromatography analyses. The resultant CPUs showed a good thermal stability with an initial degradation temperature higher than 300 • C, and their mechanical and wood bonding property can be modulated by the structures of diamine. In addition, the CPUs possessed a satisfying water resistance property with the water absorption amount lower than 2%. The green conversion of castor oil to thermoplastic polyurethane affords new opportunities in bio-based industries.