Study on preparation of SiO 2 /PTFE aerogel-like materials via atmospheric drying and their thermal insulation performance

SiO 2 aerogels are widely utilized in the heat insulation industry due to their low density and thermal conductivity. To achieve large-scale preparation and reduce the cost, hydrophobic modification of SiO 2 and solvent replacement assisted ambient pressure drying strategies are commonly employed. However, the resultant aerogels have been found to have high density, while the organic solvents used in their preparation are environmentally harmful. This study introduces a novel approach for aerogel-like materials preparation that utilizes a non-organic solvent and ambient pressure drying strategy. Methyltrimethoxysilane (MTMS) is used as the silicon source, with Cetyltrimethylammonium bromide (CTAB) serving as a surfactant to assist in the gelation of the silica sol. Additionally, Polytetrafluoroethylene (PTFE) emulsion, which shares the same charge attribute as the SiO 2 sol, is added to prevent sedimentation during the gelation process. The resulting SiO 2 /PTFE aerogel-like materials exhibits a density of 0.0874 g/cm 3 , the lower reported value for aerogel-like materials prepared using ambient pressure drying. Furthermore, this aerogel-like materials demonstrates excellent hydrophobic properties and corrosion resistance. Even after high-temperature treatment, it retains its hydrophobicity and excellent thermal insulation performance. The water contact angle remains at 140° even after 1 week of exposure to HCl treatment, and its thermal conductivity is measured at 64.43 mW/m K. Overall, this materials holds great potential for application in the field of thermal insulation. Graphical Abstract