Articular Cartilage Inspired Ultra‐Strong and Tough Bio‐Based Polyurethane Nanofiber Membranes

Bio-based polyurethanes are promising sustainable elastomers whose polymeric network structure has a decisive impact on their properties. However, existing bio-based polyurethanes face challenges in simultaneously enhancing mechanical strength and toughness. Inspired by the multilevel heterogeneous structure of articular cartilage, we propose a bionic design strategy of rigid-flexible coupled supramolecular cross-linking networks to prepare bio-based polyurethane elastomers with enhanced strength and toughness. By incorporating the asymmetric coupling of rigid furan rings and flexible aliphatic side chains into the molecular chains, a dynamic hydrogen bond network with a gradient distribution of bond energy was constructed, achieving uniform microphase separation between the soft phase (amorphous) and the hard phase (crystalline). Nanofiber membranes were fabricated by rigid-flexible coupled polyurethane electrospinning, where the microphase-separated structure is further transformed into dynamic crystalline domains. Under external force, multilevel energy dissipation is achieved through the breaking and controllable recombination of hydrogen bonds within the crystalline domain. resulting in polyurethane nanofiber membranes with significantly enhanced mechanical strength and toughness (fracture strength: 31.37 MPa, fracture strain: 731.04%, toughness: 102.13 MJ m^-3). This network design strategy expands the potential of bio-based elastomers in smart wearable textiles, flexible electronic devices, and biomedical applications, thereby advancing the development of sustainable high-performance polymers.