Shape-stable and Smart Polyrotaxane-based Phase Change Materials with Enhanced Flexibility and Fire-safety

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

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 Zn2+-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.

Sodium alginate and Chitosan aided design of form-stable Polyrotaxane based phase change materials with ultra-high latent heat

We prepared a series of highly porous Polyrotaxane/sodium alginate, and Polyrotaxane/Chitosan foam alloys according to a sustainable pathway by using water as the only solvent. The foam alloys were further used as supporter materials for poly (ethylene glycol) (PEG) encapsulation, to fabricate shape-stable bio-based phase change materials (PCMs). The pore morphology and the internal interface between PEG and foam alloys were characterized by scanning electron microscope (SEM). Due to the good compatibility between foam alloys and PEG, the PCM performed perfect anti-leakage properties. The introduction of sodium alginate or Chitosan ensures the shape stability of the PCMs during the phase transition. The PCMs performed good cycle stability and showed ultra-high latent heat (171.6 J g^-1-189.5 J g^-1). Finally, we compared the typical indicators of this work with those reported in the literature, and the comparison highlighted that the present PCMs have the significant advantages: high melting enthalpy, convenient preparation and outstanding sustainability. Notably, the work provided a sustainable idea for the design of anti-leakage and shape-stable PEG-based PCMs.