Bioinspired super-tough polyurethane elastomers with block modules using sacrificial bonds

Abstract

Stretchable and self-healable elastomers with excellent mechanical properties can find attractive applications in electronic skin, soft robotics, and electrical devices. To date, it remains a huge challenge to synthesize self-healing elastomers that integrate extreme stretchability, relatively high toughness, and high self-recoverability. Herein, inspired by biological tissues and mussel byssus, we circumvent this dilemma by introducing multiple hydrogen bonds (UPy) and metal coordination bonds (DAP-Fe(III)) into a linear polyurethane network. The self-complementary quadruple hydrogen-bond interactions between UPy dimers were incorporated as physical cross-linkages, with greatly enhanced mechanical strength and high stretchability. In addition, strong Fe-coordination bonds can readily break and re-form, a feature that facilitates energy dissipation during stretching, leading to significantly improved robustness while maintaining stretchability. The polyurethane elastomer exhibited all the desired properties, including high tensile stress (∼30 MPa), high stretchability (∼4100%), exceptional toughness (∼470 MJ m⁻³), excellent self-recoverability, and self-healing ability. This biomimetic strategy of using synergistic dynamic bonds as block modules is an alternative approach for obtaining advanced polymers.