A flexible metamaterial based on CNTs/Cellulose aerogels for broadband and ultra-lightweight microwave absorbers

Lightweight aerogel composites derived from biomass represent a promising candidate for electromagnetic wave absorption. In this study, the CNTs/cellulose aerogels with three-dimensional (3D) sheet-networks were prepared via the homogenous freezing method, and a two-layered meta-structure with periodic square resin shells was designed and optimized to further improve the absorbing properties of the CNTs/cellulose aerogels. The metamaterial absorber with the prepared CNTs/cellulose aerogel filling into the shells achieved ultra-broadband electromagnetic wave absorption in the frequency range of 4.36–40 GHz with a thickness of 8.5 mm (The relative bandwidth of the fabricated metamaterial absorber reached 160.7 %). Particularly, the radar cross-section properties of the curved CNTs/cellulose aerogel metamaterial absorber were investigated, revealing its application potential for conformal absorption devices, which would provide a new strategy for the design of ultra-lightweight conformal materials with broadband electromagnetic absorption materials.