Catalyst-Free, Reprocessable, Intrinsic Photothermal Phase Change Materials Networks Based on Conjugated Oxime Structure

The preparation and network adaptability of polymeric intrinsic photothermal phase change materials (IPPCMs) networks remain a great challenge without compromising the excellent latent heat, mechanical strength and shape stability of polymeric phase change materials (PCMs). Herein, IPPCMs integrating intrinsic photothermal effect, phase change properties and network adaptability were successfully synthesized by simultaneously introducing the conjugated p-benzoquinone dioxime (BQDO) and polyethylene glycol (PEG) into crosslinking polyurethane networks. IPPCMs enable efficient photothermal energy storage and reprocessing via BQDO-derived structures that works as photon captors and molecular heaters and that provides dynamic covalent bonds, respectively. IPPCMs have the highest latent heat of 131.7 J/g, the highest efficient photothermal con-version and energy storage efficiency of 88.7 %, the high shape stability even at 140 C, the high thermal reliability and thermal stability before and after accelerating thermal cycling, accelerated solar aging test and reprocessing. Also, introducing flexible polypropylene glycol structures can tune the mechanical properties of IPPCMs without the effect on the crystallization of PEGs. The robust approach to IPPCMs can enable the com-bination of phase change properties, the intrinsic photothermal effect and the network adaptability in a mo-lecular level, which will expand the application scope of PCMs for thermal energy storage.