Functional Polyimide/Cs <i> _x </i> WO ₃ Composite Aerogel With Photothermal Conversion Ability and Thermal Insulation Performance

ABSTRACT With the development of industrialization, there is an urgent need for energy‐saving materials with lightweight, thermal insulation and fire resistance. Here, we prepared a novel polyimide/Cs x WO 3 (PIC) composite aerogel with excellent mechanical properties, good thermal stability, thermal insulation, and outstanding photothermal conversion performance using Cs x WO 3 as a light absorber by directional freezing and imidization. Unlike conventional polyimide aerogels, the introduction of Cs x WO 3 NPs enhanced the aerogel network and effectively mitigated shrinkage and deformation during freeze‐drying. This synergistic effect endows the PIC aerogel with excellent mechanical strength (withstanding 500 cycles of fatigue tests), high thermal stability (maximum decomposition temperature close to 600°C), and strong hydrophobicity. Furthermore, the enhanced photothermal conversion efficiency, driven by Cs x WO 3 NPs, ensures efficient photon absorption. A simulation experiment on the thermal insulation performance demonstrates that employing a PIC film as the outer enclosure of a simulated insulation box can markedly enhance the thermal insulation effect, leading to a reduction of 12.2°C in the internal temperature. The novel integration of photothermal and thermal insulation properties in this composite aerogel represents a clear advancement over existing materials, making it highly promising for energy‐efficient thermal insulation technologies.