Superhydrophobic polyimide aerogels via conformal coating strategy with excellent underwater performances

ABSTRACT 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 m2 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.