Chemical Imidization Enables Polyimide Aerogels with Topological Porous Hierarchy and Ultralow Thermal Conductivity

Polyimide (PI) aerogel with high thermal stability and low thermal conductivity exhibits significant application value in the aerospace field. Nevertheless, traditional preparation methods of PI aerogel face the challenges of a complicated manufacturing process and low mechanical strength, which severely restrict their industrial scalability. Herein, a series of PI aerogels with a stable topological porous hierarchy were designed and fabricated through synergistic chemical imidization and salt template strategies. This topological porous hierarchy is composed of micropores with sizes of 5–15 μm and macropores with sizes of 200 μm–1000 μm, respectively. The fabricated PI aerogels show lightweight (0.03–0.06 g/cm3), exceptional mechanical strength, and flame-retardant properties. In particular, the PI aerogels show ultralow thermal conductivity of 0.028 W/(m·K), demonstrating outstanding thermal insulation characteristics. Moreover, the conductive PI@PPy composite aerogels were designed by depositing pyrrole (PPy) within the matrix of aerogels, and the potential applications as flexible piezoresistive sensors and photothermal conversion devices were investigated. The prepared PI aerogels demonstrate great application potential in the fields of aerospace and microelectronics.