Development of polyimide aerogel @PEG shape-stabilized phase change materials for solar–thermal conversion and infrared stealth applications

Phase change materials (PCMs) possess exceptional energy storage capacity, rendering them highly attractive for latent heat storage and thermal management applications. However, their deployment is constrained by inherent limitations, including susceptibility to leakage and poor shape stability. To overcome these issues, polyimide aerogel (PIA) was selected as the support substrate due to its low density and excellent mechanical properties. By optimizing the freezing methods of the precursor and imidization time, PI aerogel reached the maximum compressive strength of 400 kPa, while having excellent thermal insulation performance. Subsequently, polyethylene glycol (PEG) was encapsulated within PIA to form PIA@PEG shape-stabilized PCMs (SSPCMs). The PIA@PEG exhibited excellent shape stability, thermal cycling stability, latent thermal storage capacity of 161.4 J/g, and superior solar–thermal conversion performance of 83.7%. Semi-filled PIA@PEG composites with bilayer structure were developed. The metal fighter jet model, coated with bilayer PIA@PEG composites, exhibited outstanding infrared stealth and thermal camouflage performance. These results confirm that PIA@PEG composites have great potential as infrared stealth materials.