Spider silk-inspired tough and recyclable polyurethane with supercold tolerance

Developing polyurethane that can withstand ultra-low temperatures is key to expanding its applications in low-temperature environments. Spider silk demonstrates high toughness in low-temperature environments due to its hierarchical hydrogen bonds network. Inspired by spider silk, a polyurethane elastomer (SPU-DTP_x) with exceptional strength, superior toughness, low-temperature resistance, and recyclability were synthesized. The dense hydrogen bonds in the urethane bonds lead to curled and entangled molecular chains at low temperature. SPU-DTP_0.8 achieves a maximum tensile strength of 86.71 MPa, maximum elongation at break reaching 226.93% at -90 °C, with toughness of SPU-DTP_0.8 of 109.98 MJ m^-3, only 37.27% lower than that at 20 °C. Utilizing hydrogen bonds and molecular chain migration, SPU-DTP_0.8 demonstrates excellent recyclability, maintaining key mechanical properties after reprocessing. This elastomer could endure extreme supercold temperatures and offer considerable promise for creating elastic devices, flexible spacecraft, and soft robots designed for use in extremely low-temperature environments like outer space or polar areas.