Rabbit-hair-like SiO2/PI composite nanofibers with super durability for thermal insulation

Flexible composite membrane with strong strength and good thermal performances simultaneously are highly desired in broad fields. Herein, rabbit-hair-like silica/polyimide (SiO2/PI) composite nanofibers with super durability are prepared by a simple electrospinning and impregnating process. The embedded hollow SiO2 microspheres and the bamboo-shaped hollow structure of the composite nanofibers endow the membrane with excellent thermal insulation, while the externally coated thin PI layer provides quite high strength without significantly reducing its thermal stability. The obtained SiO2/PI composite membrane demonstrates high tensile strength (19.7 MPa), good flexibility (withstanding dynamic bending at least 20000 cycles), low thermal conductivity (18.7–42.8 mW m−1 K−1), multi-cycle friction resistance (500 cycles) and abrupt hot/cold alternation stability (near 400 °C). These excellent properties are mainly attributed to the 3D bonding network of the composite membrane and the impregnating-reinforcing effect on single SiO2 nanofiber. This composite membrane not only overcomes the low tensile strength and poor durability of pure SiO2 membrane, but also possesses lightweight and fireproof properties, demonstrating broad prospects in thermal insulation, anti-shock of fire/cold and wearable protective fabrics.