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• Elastic rGO/PI aerogels were prepared by the unidirectional freeze-drying method. • By adding TAB and rGO, the morphology is adjusted to a "porous honeycomb" structure. • Aerogel shows excellent pressure response range, sensitivity, and compression fatigue resistance. • The PI-TAB-rGO20 sensor exhibits good piezoresistive response at −50℃ and 180℃. Flexible conductive polyimide aerogels used for piezoresistive pressure sensors in harsh environments are often limited by brittleness, structural collapse, low elastic recovery, low sensitivity, and narrow pressure detection range. Herein, we report a simple and green method of ice-templating unidirectional solidification combined with freeze-drying and thermal imidization to obtain a flexible reduced graphene oxide/polyimide (rGO/PI) nanocomposite aerogels with a double crosslinked structure, which achieve a significant transformation of PI aerogels from brittleness to high flexibility. The strong layered structure and dense interlaminar porous network are established by the covalent crosslinking of 1,3,5-triaminophenoxybenzene (TAB) and the hydrogen bonding crosslinking of graphene oxide (GO), imparting the double crosslinked rGO/PI aerogels with unique "porous honeycomb" structure and excellent mechanical properties. Due to the synergistic effect of TAB, rGO, PI, and unidirectional freezing process, the double crosslinked rGO/PI nanocomposite aerogel shows low density (25 mg/cm3), high compression cycle stability (3000 cycles), wide pressure detection range (0–85.1 kPa), extremely short response time (about 129 ms) and excellent environmental resistance (maintaining high structural stability and pressure response even at high temperatures of 180 °C and low temperatures of −50 °C), suitable for detecting various motion signals. It is proved that the elastic double crosslinked rGO/PI nanocomposite aerogels have potential applications serving as candidate materials for piezoresistive sensors and wearable electronic protective equipment in the fields of national defense, military industry, aerospace, and other fields in extreme environments. [ABSTRACT FROM AUTHOR]

Membranes with low dielectric constant and high moisture resistance are the key material for miniaturized and integrated communication equipment as an interlayer dielectric layer. Here, a series of cross-linked PI aerogel membranes were prepared by co-polymerization and scraping coating technology. The introduction of the fluorinated blocks and benzimidazole ring structures can consequently garner novel PI aerogel membranes with fascinating dielectric properties and outstanding moisture resistance. The dielectric constants of the sample membranes are as low as 1.33 at 1 KHz and 1.32 at 1 MHz with dielectric loss as low as 0.0079 at 1 KHz and 0.0035 at 1 MHz. The water contact angle can reach 107.35° with a surface roughness value of 30.428 nm. Moreover, the PI aerogel membranes have high specific surface area and excellent thermal and mechanical properties. The thermal conductivity as low as 35.4 mW m−1 K−1 at room temperature indicates excellent thermal insulation performance. PIAM-2 is suitable as an interlayer dielectric layer for electronic components under harsh environment. In addition, the influence of surface roughness on surface wettability was also elaborated on which can provide a feasible method for the preparation of low dielectric materials with moisture resistance. [Display omitted] • PI aerogels are prepared by co-polymerization and scraping coating technology via supercritical CO 2 drying. • The synergistic effect of diamines makes aerogels with excellent thermal and mechanical property. • Thermal conductivity as low as 35.4 mW m−1K−1 indicates aerogels have super thermal insulation performance. • PIAM-2 has excellent moisture resistance with water contact angle of 107.35° and surface roughness of 30.428 nm. • Dielectric constant of PIAM-2 reaches 1.32 with dielectric loss 0.0035 at 1 MHz suitable as interlayer dielectric layers. [ABSTRACT FROM AUTHOR]

• Aromatic heterocyclic PI aerogels have been prepared by supercritical CO2 drying. • By adding PABZ, the morphology structure of PI aerogels is adjusted to fiber-island from tangled nanofibers. • Aerogels show outstanding mechanical behavior and thermal insulation (0.05 W/m·K). • PI aerogels also have rapid self-extinguishing and excellent flame retardant. The poor mechanical properties of polyimide (PI) aerogels made from biphenyl-3,3′,4,4′-tetracarboxylic dianydride (BPDA) and 4,4′-oxidianiline (ODA) limit their application. In this paper, an aromatic heterocyclic diamine, 5-amino-2-(4-aminophenyl)benzimidazole (PABZ) was introduced into the BPDA/ODA backbone to improve the comprehensive performance. The obtained PI aerogels represented excellent mechanical properties. The compressive Young's modulus was up to 53.9 MPa and the stress at 10 % strain was as high as 2.39 MPa. Meanwhile, the tensile Young's modulus ranged from 234 to 464 MPa and the tensile strength was up to 2.40 MPa. At the same time, all formulations of PI aerogels possessed outstanding thermal insulation, superb flame resistant and self-extinguishing performances, promising to be good candidates for special protective materials. Furthermore, the correlation between changes in morphology and structure resulting from the introduction of PABZ and PI aerogel properties was systematically analyzed. [ABSTRACT FROM AUTHOR]