Ultra-broadband microwave absorber and high-performance pressure sensor based on aramid nanofibers/polypyrrole/nickel porous aerogel

With the widespread use of electronic devices, microwave absorbers and wearable sensor devices appear in all walks of life. The aramid nanofibers/polypyrrole/nickel (APN) aerogels can be used as microwave absorber and pressure sensor simultaneously. In this work, aramid nanofibers/polypyrrole (AP15) aerogels (the mass ratio of aramid nanofibers to pyrrole was 1:5) were prepared by the oxidative polymerization method and then the nickel was thermally evaporated on the surface of AP15 aerogels for preparing the ultralight (9.35 mg cm^-3) APN aerogel with porous structure. The introduction of nickel was aiming to increase magnetic loss and adjust impedance matching, further improve electromagnetic wave absorption performance. The minimum reflection loss value reached -48.7 dB, and the maximum effective absorption bandwidth was 8.42 GHz with the thickness of 2.9 mm, which was attributed to the three-dimensional network porous structure and perfect impedance matching. Moreover, aramid nanofibers and three-dimensional hole structure made APN aerogels have good insulation, flame retardant, and compression resilience (500 cycles under compression strain of 50%). The polypyrrole and nickel particles enhanced the conductivity, and the final APN aerogel sensor processed highly sensitive (10.78 kPa^-1) and thermal stability. APN aerogels have significant potential in ultra-broadband microwave absorbers and pressure sensors.