Multiscale-engineered CNTs/cellulose@TPU aerogel with extended matching thickness for adaptive broadband microwave absorption

The development of microwave absorbers with superior conformability and dimensional adaptability represents a critical advancement for practical stealth applications. This study addresses this challenge through the innovative multi-scale design of a CNTs/cellulose@TPU aerogel, which exhibits both tunable dielectric properties and exceptional broadband absorption across substantially expanded thickness ranges. Precisely engineered via conformal TPU coating on a CNTs/cellulose skeleton with controlled CNTs content (4–12 wt%), the aerogel achieves optimized electromagnetic characteristics through its hierarchical porous architecture, enabling a synergy between the coordination of impedance matching and electromagnetic dissipation. The material demonstrates remarkable performance flexibility: by tuning the CNTs content from 4 to 12 wt%, the effective absorption bandwidth (RL < −10 dB) can be maintained across the entire X-band (8.2–12.4 GHz) over an extended thickness range of 4.34–7.66 mm. This unique thickness adaptability, coupled with polymorphic dissipation mechanisms including conductive network resonance, interfacial polarization, and multi-scale scattering, enables seamless integration with honeycomb absorbing structures of varying dimensions. When embedded within aramid honeycomb templates, the aerogel not only preserves its exceptional absorption capabilities but further extends its effective matching thickness range through synergistic structural interactions. The resulting hybrid metamaterial achieves efficient radar wave attenuation while offering unprecedented design flexibility for conformal applications, establishing a new paradigm for bridging the gap between performance optimization and structural integration in electromagnetic protection.