Ultra-flexible TiO2/SiO2 nanofiber membranes with layered structure for thermal insulation

High-performance thermally insulating ceramic materials with excellent mechanical and thermal insulation properties are essential for thermal management in extreme environments. In this work, SiO₂ was introduced into the crystalline lattice and grain boundary of TiO₂ to inhibit its phase transition and grain growth. Meanwhile, layered TiO₂/SiO₂ nanofiber membranes (TS NFMs) were designed and prepared. The TS NFMs had lightweight (44 mg/cm³), high tensile strength (4.55 MPa), ultra-flexibility, and low thermal conductivity (31.5 mW∙m⁻¹·K⁻¹). The prepared TS-1100 NFMs had excellent buckling fatigue resistance, which could undergo 100 buckling-recovery cycles at up to 80% strain. Low density and high diffuse reflectance endow the TS NFMs with excellent thermal insulation effects. A single-layer nanofiber membrane was composed of multiple layers of nanofibers. According to the principle of multi-level reflection, the multilayer structure had a better near-infrared reflection effect. Through the stacking effect of layers, a 10 mm thick sample composed of about 300 layers of nanofiber membranes could reduce the hot surface temperature from 1,200 °C to about 220 °C, demonstrating an excellent comprehensive thermal insulation effect. The layered TS NFMs with ultra-flexibility, high tensile strength and high-temperature resistance (1,100 °C) provide a dominant pathway in producing materials in extremely high-temperature environments.