Ambient pressure dried flexible silica aerogel for construction of monolithic shape-stabilized phase change materials

Abstract

Flexible monolithic silica aerogel was prepared using an ambient pressure drying method without extra modifying and solvent-exchange process by controlling the crosslinking degree of the network and in-situ modification of methyl groups to the siloxane backbone. The introduction of the CH3-riched trimethylmethoxysilane (TMMS) molecules transforms silica clusters from originally rigid network structure with high crosslinking degree into flexible network structure with low crosslinking degree, not only improving the flexibility of the aerogel, but also endowing the hydrophobic property. The monolith feature, flexibility, hierarchical porous structure and hydrophobicity make the aerogel an ideal porous support for fabricating shape-stabilized phase change materials (PCMs). The obtained monolithic Paraffin (PA)/Aerogel composite shows high loading amount of PCMs, enhanced phase change enthalpy and good thermal stability. It is convenient to produce diverse shapes of monolithic composite PCMs to satisfy a range of specific requirements for energy storage applications.