Three-dimensional multiscale superhydrophobic thermoplastic polyurethane/SiO2 nanowire composite sponges for durable and efficient oil-water separation

The escalating severity of environmental pollution from oil spills and chemical leaks necessitates the development of efficient, durable, and environmentally adaptable oil-water separation materials. In this study, we introduce a novel thermally induced phase separation (TIPS) technique to fabricate superelastic thermoplastic polyurethane (TPU)/silica nanowires (SiO 2 NWs) hybrid sponges with exceptional superhydrophobicity and superoleophilicity for continuous oil absorption. High aspect ratio SiO 2 NWs are uniformly distributed throughout the sponge's skeleton and surface, creating a hierarchical network of micro-nanostructures. Acting as “nano-rebars” akin to steel reinforcements in concrete, the SiO 2 NWs significantly enhance the mechanical strength of the composite while simultaneously improving its surface hydrophobicity. The sponge achieved separation efficiencies of up to 96.69 % for toluene emulsions and 89.85 % for engine oil emulsions, demonstrating its exceptional performance even under challenging conditions. The composite exhibits a water contact angle of 158°, an oil contact angle of 0°, and a 4.9-fold increase in compressive strength compared to pure TPU. Remarkably, it retains superhydrophobicity (>150°) under extreme conditions, including pH 3–11, boiling water (100 °C), baking (200 °C), and 100 cycles of mechanical abrasion. Furthermore, its superior compressibility (80 % strain), fatigue resistance (100 cycles), and reusability make it a promising candidate for large-scale oil-water separation and environmental remediation applications.