Integrating MXene Film With Recyclable Polyethylene Glycol‐co‐Polyphosphazene Copolymer as Solid–Solid Phase Change Material for Versatile Applications

Abstract Phase‐change materials (PCMs) stand a pivotal advancement in thermal energy storage and management due to their reversible phase transitions to store and release an abundance of heat energy. However, conventional solid–liquid PCMs suffer from fluidity and leakage in their molten state, limiting their applications at advanced levels. Herein, a novel Zn 2+ ‐crosslinked polyethylene glycol‐ co ‐polyphosphazene copolymer (PCEPN‐Zn) as a solid–solid PCM through dynamic metal‐ligand coordination is first designed and synthesized. The as‐synthesized PCEPN‐Zn is further integrated with an MXene film to construct a double‐layered phase‐change composite through layer‐by layer adhesion. Owing to the introduction of MXene film with low emissivity, good light absorptivity, and nonflammability, the resultant phase‐change composite not only presents a high latent‐heat capacity, good thermal stability, high thermal reliability, and excellent shape stability, but also exhibits a superior self‐healing ability, good recyclability, high adhesivity, and good flame‐retardant performance. It can be easily adhered to on most objects for various application scenarios. With a combination of the excellent functions derived from PCEPN‐Zn and MXene film, the developed phase‐change composite exhibits broad prospects for versatile applications in the thermal management of CPUs and Li‐ion batteries, thermal infrared stealth of high‐temperature objects, heat therapy in the clinic, and fire‐safety for various scenarios.