Preparation of polyimide aerogel films with high hydrophobicity and low dielectric constant under atmospheric pressure drying conditions

A series of PI aerogel composite films were prepared through adjustments made to the ratio of dianhydride and chemical imidization reagents, the crosslinker content, and the utilization of a non-solvent induced phase separation process. The prepared PI aerogel films exhibited a minimum dielectric constant of 1.39 (10 6  Hz), a maximum water contact angle of 137.8°, and demonstrated excellent recyclability. Furthermore, the prepared polyimide aerogel films demonstrated exceptional thermally stable characteristics, with Td 5% maintained at approximately 510 °C, Tg values remaining above 230 °C, and a low coefficient of thermal expansion, at 55.8 ppm/K. The prepared PI aerogel films exhibit a high degree of porosity (74.1%), a relatively low density (0.392 g/cm 3 ), and considerable tensile strength (up to 6.2 MPa). It has been demonstrated that these polyimide aerogel films are highly promising for the construction of high-frequency microelectronic devices. Graphical abstract