Designed Composite Aerogels With Solid–Solid Phase Transition and Nanoscale Pores for Infrared Stealth

Abstract Phase change materials (PCMs) and thermal insulation materials have garnered significant attention in infrared stealth applications due to their excellent temperature regulation capabilities. However, traditional PCMs often face leakage issues or are unable to balance porous structure retention. In this work, a composite aerogel with dual solid skeletons is designed via homogeneous mixing. The composite aerogel not only features the nanoporous structure and thermal insulation properties but also possesses solid–solid phase transition capability without PCM leakage. Compared to pure polyimide (PI) aerogels, the composite aerogel exhibits lower thermal conductivity due to its lower density and more intricate pore structure. The composite aerogel retains a maximum phase transition enthalpy of 111 J g −1 and can significantly slow surface temperature rise under high‐temperature conditions. In addition, the composite aerogels exhibit excellent cyclic stability and long‐term durability, further demonstrating their potential for applications in complex infrared stealth scenarios. When the composite aerogel is used to cover a graphite sheet at 136 °C, the surface infrared radiation temperature is reduced to only 25.5 °C, demonstrating excellent infrared stealth performance. This study provides new insights for designing high‐efficiency infrared stealth materials with flexible temperature regulation capabilities.