Block Building Architecture for a Multifunctional Broadband Electromagnetic Wave Absorber Based on the Freestanding Resistive Film

As the critical component in the electromagnetic (EM) wave shielding and stealth technology, using broadband EM wave absorbers in harsh environments is still challenging in practical applications. In this letter, a novel way of realizing the broadband absorbers with a block building method is proposed to broaden their absorptivity to different application scenarios. In particular, the synthesis of the self-supported carbon nanotube–cellulose nanocrystal (CNT–CNC) film, which acts as a resistive layer, is independent of selecting substrates during fabrication and assembling. Therefore, replacing the substrates to meet different application requirements is easy. We experimentally demonstrate the application of a block building method in realizing a high temperature-resistant and self-repairing EM wave absorber by combining the CNT–CNC film with ceramics and supramolecular thermoplastic urethane substrates, respectively. Moreover, the CNT–CNC film is compatible with laser etching and further offers a convenient way of tuning the absorption frequency after incorporating frequency-selective surface design. The proposed block building method offers insights into designing multifunctional absorbers.