Biocompatible Poly(urethane-urea) Elastomers with High Toughness and Elastic Restorability

Biocompatible elastomers that combine high toughness with excellent elastic restorability hold great promise for biomedical applications; however, achieving the toughness and elasticity simultaneously in a single material remains a significant challenge. In this study, polycaprolactone-based poly(urethane-urea) (PUU) elastomers that exhibit excellent mechanical properties as well as superb biocompatibility are reported. Hydrazide chain extenders are employed to introduce abundant hydrogen bonds to ensure high toughness, while isophorone diisocyanate, having a bulky steric structure, is used to limit the aggregation of hard segment clusters and suppress strain-induced crystallization, thereby enhancing the elastic recovery. The obtained PUU elastomer achieves a toughness of 333.2 MJ m^-3 and a strength of 63.7 MPa, with low residual strains of ∼11% and ∼44% at 100% strain and 400% strain, respectively. In addition, the elastomer demonstrates good healability, recyclability, and biocompatibility. These combined properties position the material as a promising candidate for biomedical applications and provide valuable insights for future material design.