Polyimide-Coating-on-Aramid nanofiber strategy toward ultralight organic aerogels with multifunctional properties

High-performance aerogels are highly desirable in the fields of thermal barriers, drug delivery, and mechanical cushions; however, most of the reported aerogels are limited by complex preparation processes and single functionality. To address such issues, in this study, we prepare a series of aramid nanofiber (ANF)/polyimide (PI) multifunctional composite organic aerogels via a facile polyimide-coating-on-aramid nanofiber (PCoA) strategy. This strategy utilizes PI to coat on the surface of ANFs and construct numerous mesopores within the ANF three-dimensional network skeleton to make the ANF/PI composite aerogels exhibit superior multifunctional properties, such as outstanding thermal and acoustic insulation, mechanical strength, thermal stability, flame retardancy, and hydrophobicity. In particular, the as-prepared composite aerogels with a PI content of 20 wt% exhibit a thermal conductivity of 23.20 mW/mK, which is lower than that of air, and their specific Young's modulus reaches 32.57 MPa/(g/cm(3)), the highest among all previously reported organic aerogels, at a density of only 14.86 mg/cm(3). The composite aerogels are destined to be extremely valuable as they can combine so many remarkable properties in a single package. Currently, the composite aerogels have been available in the form of ultrathin thermal insulation films at a thickness of only 100 mu m, which can provide effective heat protection in microelectronic devices, and remain a terrific ability to operate under extreme conditions. Owing to these superior multifunctional properties, the ANF/PI composite aerogels show enormous potential for application in numerous fields, such as thermal management, environmental governance, catalysis, and energy storage.