Superhydrophobic polyimide aerogels via conformal coating strategy with excellent underwater performances

The hydrophobilization of aerogels is critical for their long-term application due to their highly open-porous structures, while the hydrophobilization strategies for polyimide (PI) aerogels are limited. In the present work, a feasible strategy to synthesize superhydrophobic PI aerogels is proposed via a conformal-coating process. The resulting PI aerogels (F-PI) exhibit high contact angles up to 156°. Impressively, the F-PI aerogels show excellent water-resistant capacity not only in the ambient condition but also in the high-pressure water up to 0.5 MPa, where the liquid cannot or only partially permeate into the aerogel's open pores. Besides, the F-PI aerogels possess high Brunauer–Emmett–Teller surfaces areas (185 m 2 g −1 ), high Young's modulus (3 MPa), low thermal conductivity (0.056 W m −1 ·k −1 ), and variable densities. All these parameters are found to be well preserved after high pressure (0.1–0.2 MPa) water treatment, further indicating the excellent water-resistant performance of the F-PI aerogels. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137 , 48849.