Tailoring dielectric relaxation time in ultralight graphene aerogels for ultra-broadband microwave absorption and multifunctional applications

Composite aerogels composed of reduced graphene oxide (RGO), single-walled carbon nanotubes (SWNTs), and polyimide (PI) with an oriented porous structure exhibit flexible, high-performance microwave absorption and a tunable porosity. The polarization relaxation time is varied by adjusting the heat treatment temperature to achieve ultra-broadband microwave absorption at lower thicknesses. SWNTs contribute to the control of aerogel morphology and significantly improve its mechanical toughness. The prepared aerogel has a bulk density of 9.13 mg/cm³ and excellent absorption properties with a minimum absorption peak of −64.5 dB and an effective absorption bandwidth (EAB) of 9.14 GHz. Through experimental comparison and time-domain finite integration calculation, the effect of oriented porous structure on the electromagnetic loss mechanism and performance was elucidated, which can be used for porous wave-absorbing materials. At the same time, the light and flexible PGS composite aerogel fabric is also remarkably flexible, and its excellent mechanical and thermal insulation properties are attributed to its unique orientated microchannel structure. This low-cost, simple and high-performance approach will greatly simplify the application of multifunctional microwave-absorbing materials in wearable and other extreme conditions, including high-temperature environments.