Solid–Solid Phase Change Composites Templated from Thermoreversible Octadecane Gel-in-Water Emulsions

Phase change material (PCM)-microencapsulated monolithic composites hold considerable promise in applications for latent heat storage and release, but they face the issue that the microencapsulated PCMs, when in the liquid state, might leak via an open pathway. Herein, we report the synthesis of solid–solid phase change composites from thermoreversible octadecane (OD) gel-in-water emulsions through in situ closed-cell polyHIPE generation and encapsulation. The thermoreversible OD gels, formed simply by heating OD and a low-molecular-weight gelator together, exhibit a reversible crystal-gel phase transition and a gel–liquid phase transition. Through light-driven interface-initiated radical polymerization, solid–solid phase change composites have been fabricated from Pickering emulsions containing the thermoreversible OD gel as the dispersed phase via in situ closed-cell polyHIPE generation and encapsulation. The resulting composites show predesignable external shapes, negligible leakage even for fractured samples after 10 heating–cooling cycles, high flexibility, and robust compression. The composites possess extremely high heats of melting and crystallization (up to 197.5 J/g) and good reusability. The advantageous properties enable the solid–solid composites to be excellent candidates for efficient latent heat storage and temperature management.