A firefly-inspired smart aerogel-based phase-change composite for intelligent microwave absorption

Intelligent electromagnetic functional composites exhibit dynamic electromagnetic parameters, offering potential solutions for electronic devices in complex environments. Traditional methods relying on composites' volume changes often result in structural instability and poor environmental adaptability. Herein, we design an intelligent phase-change composite that mimics the firefly's luminescent "on-off" switching behavior, which consists of a polyacrylonitrile/polyvinyl pyrrolidone/polyvinyl alcohol/carbon nanotubes (3PC) aerogel and polyethylene glycol (PEG). This unique structure features temperature-responsive characteristics, enabling effective modulation of the composite's dielectric constant. Temperature variations induce PEG's phase transition and dynamically alter hydrogen bonding interactions within the composite. 3PC/PEG demonstrates innovative and reversible thermal-responsive switching properties: 3PC/mPEG in the molten state achieves a minimum reflection loss of -23.9 dB, while 3PC/cPEG in the solidified state exhibits a reduced minimum reflection loss of -8.9 dB. This mechanism enables temperature-dependent modulation of the dielectric constant, facilitating controlled microwave absorption and attenuation. Furthermore, the composite achieves switchable microwave absorption performance across different temperature ranges by regulating the molecular weight of the absorbed PEG. It also demonstrates modulatable electromagnetic interference (EMI) shielding properties and exceptional infrared stealth capability. This work advances the development of intelligent electromagnetic functional composites and presents significant potential for practical applications in adaptive electromagnetic management.