Closed-Cell, Phase Change Material-Encapsulated Monoliths from a Reactive Surfactant-Stabilized High Internal Phase Emulsion for Thermal Energy Storage
Tao Zhang, Zhiguang Xu, Huanjie Chi, Yan Zhao
Abstract
Closed-cell, high internal phase emulsion (HIPE)-templated polyHIPEs are promising for phase change material (PCM) encapsulation, but the removal of HIPE stabilizers from such monoliths is challenging. Here, we report the use of a reactive HIPE stabilizer to prepare closed-cell, PCM-encapsulated polyHIPE monoliths for thermal energy storage application. The reactive stabilizer, end-capped Pluronic F127 with acrylate, was covalently incorporated into the polyHIPE macromolecular network simply through light-induced, interfacially initiated radical polymerization, omitting the need of stabilizer removal for conventional inert stabilizing surfactants. When a PCM, octodecane (OD), was used as the dispersed phase, OD-encapsulated polyHIPE monoliths were fabricated. The polyHIPE encapsulation slightly decreased the crystallization (heat release) temperature but, surprisingly, increased the melting (heat storage) temperature, facilitating latent heat storage for daily use. The monoliths exhibited extremely high heat capacity and showed high reusability. The simple fabrication, high stability/reusability, and high heat capacity enabled the OD-encapsulated monoliths to be an excellent candidate for latent heat storage and release.