Emulsion-based monoliths with a solid-gel phase-transition and a solid-solid phase-transition for latent heat storage

Emulsion-based, phase change material-encapsulated monoliths are promising for latent heat storage. However, such monoliths usually exhibit a solid-liquid phase-transition and the one-only phase-transition might hinder the monoliths for more potential applications. Herein, we report the synthesis of emulsion-based monoliths with a solid-gel phase-transition and a solid-solid phase-transition for latent heat storage. The solid-gel phase-transition was from melting and crystallization of octadecane-in-crosslinked poly(octadecyl acrylate) that was formed via radical polymerization of the dispersed phase within oil-in-water emulsions, and the solid-solid phase-transition was from melting and crystallization of the crosslinked polyethylene oxide blocks that were synthesized via the interface-initiated radical polymerization of the continuous phase. The resulting emulsion-based monoliths showed negligible mass loss during the heating at 60 degrees C for 8 h, and exhibited two different crystallization (heat release) temperatures and melting (heat storage) temperatures, corresponding to the solid-gel transition and the solid-solid transition. Moreover, the monoliths possessed quite high heat density (up to 136.4 J/g), and the heat density did not deteriorate over 20 heating-cooling cycles, showing high reusability. The extremely low leakage, double phase-transitions and the high reusability make the monoliths to be a good candidate for latent heat storage. image