Lightweight PAN/TPU/Graphene Nanofiber Sponges via Solution Air-Assisted Electrospinning for Thermal Insulation

Materials with effective thermal insulation performance are critically important for people living in extremely cold environments. However, the thermal insulation materials fabricated by conventional methods typically suffer from excessive bulkiness, inadequate thermal insulation properties, and limited functionality. Herein, we report lightweight nanofibrous sponges with integrated thermal insulation, photothermal heating, and antibacterial performance via a facile and scalable solution air-assisted electrospinning strategy. By exploiting the humidity-induced phase separation during jet stretching, curly nanofibers are fabricated and entangled into a three-dimensional structured assembly with high porosity and ultralow volume density (4.01 mg cm–3). The resulting nanofibrous sponges also exhibit excellent mechanical robustness, which can sustain loads up to 5000 times their own weight. Furthermore, the incorporation of monolayer graphene endows the sponge with efficient solar-to-thermal energy conversion while preserving its porous structure. Consequently, the obtained sponge for thermal insulation achieves a low thermal conductivity of 27.85 mW m–1 K–1 and rapid temperature increase to 52.6 °C within 5 min under simulated solar irradiation, together with outstanding antibacterial activity (99.9%). This work provides a practical avenue toward multifunctional thermal insulation materials for wearable protection and extreme-environment applications.