Bioinspired MXene@PNIPAAm Composite Enables Switchable Microwave Absorption

Stimuli-responsive microwave absorbing (MA) materials are highly desirable for next-generation electromagnetic interference protection systems, as they enable adaptive regulation of electromagnetic responses under dynamic service conditions. Herein, a bioinspired temperature-responsive composite based on Ti3C2Tx MXene and poly(N-isopropylacrylamide) (PNIPAAm) is fabricated via in situ polymerization of PNIPAAm within MXene dispersions. Benefiting from the reversible conformational transition of PNIPAAm chains induced by temperature variation, the MXene nanosheets undergo a dynamic bridging-disconnection transformation, analogous to the opening and closing behavior of plant leaf stomata. This microstructural evolution enables adaptive reconstruction of the conductive network, thereby modulating dielectric properties and realizing switchable microwave absorption performance. At 50 °C, the composite delivers a minimum reflection loss of −47.8 dB and a broad effective absorption bandwidth of 5.9 GHz, whereas negligible absorption is observed at 20 °C. This work demonstrates a viable strategy for constructing intelligent, stimuli-responsive MA materials based on MXene@polymer architectures, offering promising prospects for advanced EMI protection and adaptive electromagnetic devices.