Mechanically strong and thermally insulating polyimide aerogels by homogeneity reinforcement of electrospun nanofibers

High-performance thermal insulating materials are greatly needed in many areas. Polyimide aerogels by freeze-drying method have shown great potential as thermal insulating materials. Improving the mechanical performance of polyimide aerogels, meanwhile without deteriorating their thermal insulating performance, is very significative. In this work, a significant homogeneity reinforcement of polyimide aerogels has been achieved by using electrospun polyimide nanofibers as the reinforcing fillers. Short nanofibers could improve strength and toughness of polyimide aerogels by dispersing stress along the pore wall and nanofibers via mechanical interlocking effect due to the good compatibility between them. Consequently, the nanofiber-reinforced polyimide (NRPI) aerogels exhibit better structural formability and excellent mechanical performance, showing compressive modulus of 3.7 MPa with a density of 54.4 mg cm−3, nearly twice that of neat polyimide aerogel. More importantly, owing to the high porosity and intertwined three-dimensional network, NRPI aerogels exhibit better thermal insulating properties compared with commercial insulating materials, especially at high temperatures. Therefore, the nanofiber reinforced polyimide aerogels with good mechanical performance are promising candidates for thermal insulating applications.