Preparation of paraffin/SiO2 aerogel stable-stabilized phase change composites for high-humidity environment

Abstract

The shape stabilization ability of solid–liquid phase change composites (PCCs), which are determined by the interaction between the terminal group of the phase change material molecule and the surface properties of the porous matrix material, is a prerequisite for long-term stable work of PCCs. Here, mesoporous SiO2 aerogel (MSA) surface properties were engineered to regulate the interactions between paraffin wax (PW) composites. To evaluate the effect of the surface properties of MSA on the stability of the composite, the sol–gel method combined with a supercritical drying process was firstly used to prepare CH3/HO–MSA. Then, HO–MSA and CH3–MSA were obtained by hydroxylation and alkylation modification on the basis of the as-prepared CH3/HO–MSA, respectively. The alkyl group modified on the surface of the MSA pores eliminates the phase separation of PCCs caused by the hydrogen-bonding interaction between MSA and water molecules. Therefore, the obtained CH3–MSA/PW has no leakage for more than 24 h even in an environment of high humidity and a temperature exceeding the melting point of PW. In addition, large phase change latent heat, good thermal conductivity and thermal stability are also well achieved. This paves the way for the development of PCCs for use in high-humidity environments.