Eco-friendly approach for preparation of hybrid silica aerogel via freeze drying method

In this paper, an eco-friendly method of producing hybrid silica aerogels by freeze-drying method (FD) is proposed. In the freeze-drying system, deionized water was the only solvent, hybrid aerogels were prepared by acid–base catalysis and sol–gel method using methyltrimethoxysilane (MTMS) and water–glass as co-precursors. The microstructure, specific surface area, pore size distribution and thermal properties of the hybrid aerogels were characterized and analyzed. It was found that all samples exhibited the dual-mesoporous structures, and the molar ratio of co-precursors had a significant effect on the performance of aerogels. The tap density decreased and the porosity increased with the increase in the molar ratio of MTMS, while the thermal diffusion coefficient and thermal conductivity of aerogel decreased first and then increased. Especially when the molar ratio is 2.0, the hybrid aerogels exhibited excellent insulation performance, such as thermal diffusion coefficient of 0.0183 mm s −1 , thermal conductivity of 0.0460 W(m k) −1 and great thermal stability up to 540 °C. It illustrates that hybrid aerogels have broad application prospects as insulation materials.