Rational design of sustainable polyurethanes from castor oil: towards simultaneous reinforcement and toughening

Sustainable polyurethanes prepared from castor oil and diisocyanates show very low strength and toughness, due to the highly cross-linked and flexible structure. Herein, we report a new strategy to simultaneously reinforce and toughen castor oil-based polyurethane via incorporating a stiff component (isosorbide, IS) to enhance network stiffness and reduce crosslink density. The crosslinking degree decreases while the strength, moduli, ductility and heat resistance significantly increase accordingly with increasing IS content. The tensile behaviors are tunable over a broad range (either as elastomers or as plastics) depending on the compositions. The polyurethanes show excellent thermal stability with onset decomposition temperature higher than 280°C. The investigation provides a new hint for future design and fabrication of high performance sustainable polymers from other vegetable oils.