Sustainable metal-free polyurethane elastomers from bile acids: self-healing properties and biocompatibility

Currently, self-healing polymers with superior elasticity have made great progress in healthcare devices and flexible electronics. Benefiting from rigid skeletons and hydroxyl groups of bile acids, herein sustainable self-healing polyurethanes have been developed via an alternative metal-free strategy in which bile acid units and oligo(ethylene glycol)s serve as hard and soft segments, respectively. The bile acid based polyurethane could achieve a similar mechanical performance (7.96 MPa of Young's modulus) to certain soft tissues and maximum self-healing efficiency of 90% in tensile strength for 3 h. Multiple hydrogen bonds originated from hydroxyl groups of bile acids and urethane bonds synergistically attribute to self-healing ability, which represents the first example that quadruple hydrogen bonds of sustainable molecules driven elastomers have been reported. Moreover, taking into account the desirable biocompatibility both in vitro and in vivo, it is highly anticipated that these sustainable metal-free self-healing polyurethane elastomers would be explored for practical applications, such as soft tissue repairing.