Long‐Term Infrared Stealth by Sandwich‐Like Phase‐Change Composites at Elevated Temperatures via Synergistic Emissivity and Thermal Regulation

Abstract The rapid development of infrared surveillance technologies has attracted great attention for scientists to design advanced functional materials with prominent infrared stealth and thermal camouflage effectiveness. In the current study, a sandwich‐like functional composite based on a crosslinked polyimide aerogel, a meso‐erythritol (mE)‐based phase‐change composite, and an MXene film has been developed to achieve long‐term thermal camouflage at elevated temperatures. In this composite system, the lower aerogel layer can act as a barrier to insulate heat transfer through its layer‐stacking structure under ultralow directional thermal conduction. The introduction of the middle phase‐change composite layer ensures that the composite system obtains a dynamical temperature‐regulation capability through sensible and latent heat absorption of mE as a phase change material, while the upper MXene layer provides a very low emissivity surface for the system. As a result, the developed composite achieves a significant reduction in the thermal radiation temperature of a high‐temperature target. Moreover, the MXene film exhibits good electromagnetic interference shielding effectiveness, making the sandwich‐like composite obtain a thermal camouflage capability in various complicated scenarios. This work provides a promising approach for the design of advanced functional materials to realize long‐term infrared stealth and thermal camouflage of high‐temperature targets in security protection and counter‐surveillance.