Highly flexible ceramic nanofibrous membranes for superior thermal insulation and fire retardancy

Ceramic membranes are attractive for thermal management applications due to its lightweight and ultralow thermal conductivity, while it is indispensable to address the long-standing obstacle of its poor mechanical stability and degradation under thermal shock. In this work, a series of the organic polymer template-modulated yttria doped zirconia (YDZ) nanofibrous membranes with lightweight, superior mechanical and thermal stability are developed through a cost-effective, scalable sol-gel electrospinning and subsequent calcination method. The YDZ membranes demonstrate excellent flexibility and foldability, which can be attributed to the tetragonal phase and small crystallite size of the YDZ fibers due to the presence of yttria. Besides, the fibrous size, grain size, mechanical and thermal stability of YDZ nanofibrous membranes could be tailored by varying the species and molecular weight of polymer template. The remarkable performances are obtained through the poly(vinyl pyrrolidone) (PVP) template YDZ nanofibrous membranes, featuring the superior tensile strength up to ~ 4.82 MPa, excellent flexibility with bending rigidity ~ 26 mN, robust thermal stability up to 1,200 °C, ultra-low thermal conductivity of 0.008–0.023 W·m⁻¹·K⁻¹ (25–1,000 °C), and excellent flame retardancy with tolerance of flame up to 1,000 °C. The remarkable properties can be attributed to the smaller fibrous size, and higher grain size resulting from PVP template. This robust material system is ideal for thermal superinsulation with a wide range of uses from energy saving building applications to spacecraft.