Biphasic Transition Induced Intelligent Switchable Microwave Absorption in LCE/VO2 Composites.

Intelligent microwave absorption (MA) materials, which are characterized by their capacity to dynamically adjust MA performance in response to real-time demands, hold great promise for applications across both civilian and defense sectors. In this study, we introduce a series of liquid crystal elastomer/vanadium dioxide (LCE/VO2) composites that exhibit switchable MA properties through a synergistic biphasic transition mechanism. The intelligent switching behavior arises from the synergy of three effects: dipole polarization changes associated with the LCE nematic-isotropic transition, conductivity variations stemming from the VO2 metal-insulator transition, and alterations in interfacial polarization between the two phases generated from the thermal stress imposed on the LCE. This synergistic effect facilitates dynamic modulation of the real permittivity (ε') as well as the conductive (εσ″) and polarization (εp″) parts of the imaginary permittivity, thereby enabling switchable MA. Benefiting from the biphasic cooperative modulation, the designed composites exhibit an effective absorption bandwidth (EAB) ranging from 0 to 3.3 GHz (covering 80% of the X-band) and a radar cross-section (RCS) achieving a maximum ΔRCS of 33.2 dB m2 (incident angle of 330°). These results highlight the promise of LCE/VO2 composites as intelligent MA materials, opening new avenues for adaptive stealth applications in electronic devices and aerospace technologies.