Multifunctional Phase Change Films with High Mechanical Strength, Thermally Induced Switchable Adhesion, and Shape Recoverability for Infrared Stealth.

The application of organic solid-liquid phase change materials (PCMs) is limited for the leakage problem after phase change and high rigidity. In this work, a novel flexible solid-solid PCM (DXPCM) was synthesized using a block copolymerization process with polyethylene glycol (PEG) as the energy storage segment. The phase transition temperature (from 36.2 to 49.4 °C) and enthalpy (from 83.27 to 123.35 J/g) of DXPCM could be changed through adjusting the molecular weight of PEG. The introduction of hard chain segments endowed DXPCM with excellent flexibility, foldability, and mechanical properties at room temperature. The large number of internal hydrogen bonds and π-π stacking provided DXPCM with interesting thermally induced switchable adhesion and recyclability. The storage and release of elastic potential energy ensured that DXPCM could recover its original shape after being deformed by external forces. It is worth mentioning that DXPCM exhibits excellent infrared stealth capability as it can absorb and release latent heat for a long period of time. In conclusion, this work developed a novel solid-solid phase change film with high mechanical strength, thermally induced switchable adhesion, and shape recovery capability, which has great potential for application in infrared stealth.