Reusable Ultratough Supramolecular Polyurethane-Urea Elastomer via Rigid-Flexible Mismatched Hard Segments and a “Train Coupling Mechanism”

Supramolecular interactions have enabled the development of high-strength and tough polyurethane elastomers with exceptional mechanical properties and functionality. Herein, we report a supramolecular polyurethane-urea (PUU) elastomer engineered through rigid-flexible segmented hydrogen bonding and a biomimetic “train coupling mechanism”, achieving both ultrahigh strength and facile recyclability. By leveraging mismatched rigid-flexible supramolecular interactions between adipic dihydrazide (AD H-bonding) and 2-ureido-4[H]-pyrimidinone (UPy H-bonding) hard segments, the elastomer demonstrated enhanced toughness and energy dissipation. This work provided an in-depth analysis of AD and UPy H-bonding, elucidating their respective roles in the mechanical and dynamic properties of the PUUs. The sample PUU-AD-5UP exhibits outstanding tensile strength (64.4 ± 5.6 MPa) and toughness (700 ± 59 MJ·m^–3). Owing to the dynamic UPy “couplers”, the as-prepared material enables room-temperature self-healing and ethanol-assisted recycling capability with 95% efficiency of tensile strength. Furthermore, an ion-conductive PUU-AD-5UP (ICPUU-AD-5UP) composite was prepared, achieving a good combination of high tensile strength (28 MPa), ionic conductivity, and recyclability. This supramolecular design strategy provides valuable insights into developing high-performance, reusable flexible electronic skins.