Supertough, Resilient, and Healable Thermoplastic Poly(Urethane Urea) Elastomers by Dense Packing of Hydrogen‐Bonding Arrays

Abstract The structure and density of hydrogen bonds in thermoplastic poly(urethane urea) (TPU) elastomers play a pivotal role in determining their microscopic structures and macroscopic thermomechanical performances. In this context, the syntheses and characterizations of a class of poly(caprolactone) (PCL)‐based TPU elastomers containing acylsemicarbazide (ASCZ) groups that afford densely packed hydrogen‐bonding arrays are reported. Benefiting from the strong intermolecular interactions, these TPU elastomers display ultimate engineering stress and elongation up to 70 MPa and 1100%, respectively, and therefore considerable toughness of 260 MJ m −3 . Meanwhile, crystallization of PCL segments in the elastomers is strongly suppressed by the hydrogen‐bonding arrays, giving rise to their good elasticity at strains as high as 1000%, superior to nearly all polyester‐based TPU analogs. With identical hard segment content, fine‐tuning of the hydrogen‐bonding density via the chain extender chemistry leads to divergent upper working temperatures and healing rates, despite uniformly superb ultimate strength, elongation at break, toughness, and resilience at room temperature.