Synergistic Hydrogen Bonding Topology Enables Ultra-Robust Recyclable Polyurethane Elastomers for Multifunctional...

There has long been a trade-off between mechanical strength and toughness in polyurethane (PU) elastomers. This limitation arises from stress concentration and inefficient energy dissipation within the rigid domains. Therefore, a gradient hydrogen bonding topology strategy is proposed that constructs hierarchical crosslinked networks incorporating both strong (urea-based) and weak (ester-based) hydrogen bonds. By precisely controlling these bonds, an optimized polyurethane elastomer (SPU_0.5, where 0.5 denotes the crosslinking density parameter) is achieved with a tensile strength of 27.4 MPa-2.5 times higher than that of systems dominated by weak hydrogen bonds-alongside exceptional toughness (188.1 MJ m^-3) and fracture energy (115.8 kJ m^-2). These values surpass those of most previously reported PU elastomers and even exceed the toughness of natural spider silk (100-160 MJ m^-3). The dynamic nature of the weak hydrogen bonds enables rapid self-healing (100% recovery after 24 h at 80 °C) and excellent recyclability (less than 5% performance loss after five cycles), while the strong hydrogen bonds maintain structural integrity. Notably, integrating silver-coated SPU_0.5 into wearable sensors enables real-time monitoring of limb movements, facial expressions, and voice recognition, providing the way of health monitoring. This work offers insights into designing mechanically adaptive polymers through hierarchical-level engineering.