Novel phase-change material based on stearic-acid@MOFs@SiO2 with perfect impermeability promoted by coordination with unsaturated metal sites

In this study, to achieve excellent impermeability and thermal storage performance of metal-organic framework (MOF) based composite phase change materials (PCM), an encapsulation method was prepared by utilizing unsaturated metal sites of MOF, and the PCM composite SA@MOFs@SiO 2 were prepared. Stearic acid is adsorbed into the MOF pores through adsorption before encapsulation. To achieve high impermeability, the unsaturated metal site of MOFs forms a coordination Me-SH bond with 3-mercaptopropyltriethoxysilane (KH590), then dense silica was formed on PCM surface through the hydrolysis condensation reaction of both KH590 and triethoxysilane (TEOS). The heat storage of SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 composite can reach 113.89 J/g, and the melting permeability was as low as 0.69 %, exceptional chemical stability can be obtained at 70 °C for 10 days. This work provides a general method for designing a variety of MOF-based phase-change composites with superior impermeability, demonstrated by three different MOFs derived PCMs. These will be promising materials in the fields of textiles, architecture, solar energy applications , and etc.