Solvothermal imidization to polyimide composite aerogels by vacuum drying

Facile techniques that are time- and cost-saving nowadays are required for preparing PI aerogels with low density, structural stability, high mechanical performance, and thermal stability in wide practical applications. In this work, a strategy of solvothermal imidization followed by vacuum drying, using electrospun short polyimide (PI) fiber as supporting skeleton, was reported to prepare high-performance PI aerogels without the implementations of special drying instruments. The mechanism of "self-gluing" of the fiber-constructed skeleton of PI during preparation process was applied to enhance the strength of the precursor gels and achieve structural stability. PI aerogels with hierarchically cellular structure possessed bimodal interconnected pores, tunable densities (From 39.1 mg cm−3 to 55.8 mg cm−3), and high porosity (>96%) are reported. The aerogels showed low energy-loss coefficients for 103 cyclic compressive tests and initial degradation temperature high than 400 and 500 °C in air and nitrogen atmosphere, respectively.