Heterocyclic aramid nanofiber aerogel membrane with ultra-low dielectric constant and excellent thermal insulation based on upcycled waste heterocyclic aramid fiber

Waste heterocyclic aramid fiber (HAF) retains the same or similar properties as the original fiber. It will be a waste of resources if these waste HAFs cannot be handled sensibly and efficiently. Based on the above background, in this paper, discarded HAFs are recycled for the preparation of heterocyclic aramid nanofiber aerogel membrane (HANFAM) at greatly reduced cost. The strategy started from the chemical exfoliation of discarded HAFs, which were converted into HANFAM through the bladed coating followed by the freeze-drying techniques. The prepared HANFAMs have tunable and ultra-low dielectric constants and low dielectric loss, with the dielectric constant range of 1.31–1.47 and the dielectric loss range of 0.0026–0.0073 at 1 MHz, which are much lower than other reported aerogel materials. Therefore, it can be used as an important substrate to secure high-speed circuit transmission in integrated electronic devices. In addition, the obtained HANFAMs exhibit a high initial thermal decomposition temperature of 514 °C and a low thermal conductivity of 28.87–40.73 mW/(m·K). This work provides a new perspective on the fabrication of HANFAMs with ultra-low dielectric and excellent thermal insulation based on upcycled waste HAFs.