High-performance flexible reduced graphene oxide/polyimide nanocomposite aerogels fabricated by double crosslinking strategy for piezoresistive sensor application

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.