Effect of different reaction solvents on the hydrophobic and structural properties of silica cryogels

The experimental results on the microstructural and physical properties of the TEOS-based silica cryogels have been reported. The cryogels were produced by two-step sol-gel process followed by vacuum freeze drying. The wet gels were synthesized via acid-base catalysis using tetraethoxysilane (TEOS) as a silica precursor, the different solvents containing ethanol (EtOH), methanol (MeOH) and tert-butanol (TBA), the molar ratio of TEOS / solvent were varied from 1:6 to 1:13. Further, the microstructure and specific surface area of the cryogels were analysed by Scanning Electron Microscopy (SEM) and nitrogen absorption/desorption isotherms. The hydrophobicity of the cryogels was studied by contact angle. It was found that the highest specific surface area (1040.17 m²/g) was obtained with the solvent of MeOH. The lowest density (0.074 g/cm³) was acquired with the solvent of EtOH.