Thermostable and stretchable core-shell aerogel fibers for thermal insulation application

Abstract Aerogels are among the most suitable thermal insulation materials for next generation textiles, yet they face an inherent structural conflict between high porosity for insulation and a dense network for mechanical strength. Herein, we propose a core-shell aerogel fiber architecture to resolve this conflict via a functional partitioning strategy. Using a coaxial wet-spinning method assisted by ambient-pressure drying, we fabricate aerogel fibers with a shell of aramid nanofiber (ANF) network and a core of thermoplastic polyurethane (TPU) foam. This hierarchical gradient porous structure integrates nano/micro-scale pores, endowing the core-shell aerogel fibers with an ultralow thermal conductivity of 29.82 mW·m-1·K-1 and superior thermal insulation performance from -196 °C to 200 °C. The TPU core provides flexible support and stretchability, delivering a tensile strength of 8.9 MPa, an elongation at break of 59.3%, and excellent stretch recovery performance to the aerogel fibers. Meanwhile, the thermostable ANF shell layer ensures thermal stability and structural integrity of the aerogel fibers under extreme thermal conditions. Therefore, the ANF@TPU core-shell aerogel fibers developed in this work achieve a favorable balance among thermal insulation, mechanical properties, and thermal stability, demonstrating promising potential in extreme temperature applications.