Flexible and super hydrophobic polymethylsilsesquioxane based silica aerogel for organic solvent adsorption via ambient pressure drying technique

Practical applications of silica aerogels have been restricted due to their hydrophilicity, fragility and high cost of supercritical drying technique. In this work, the successful synthesis of the super hydrophobic polymethylsilsesquioxane (PMSQ) based silica aerogel via the sol-gel technique and ambient pressure drying method is proposed. Dimethoxydimethylsilane (DMDMS) and methyltrimethoxysilane (MTMS) are used as the co-precursors. The MTMS/DMDMS volume ratio is determined at 3/1, and the water contact angle as large as 165°, confirming its super hydrophobicity. The [sbnd]CH₃ groups rendering the hydrophobicity gradually disappear after heat treatment at 400 °C. The aerogel is composed of the spherical and smooth secondary particles with diameters at around 3–4 μm, with the most probable pore diameter locating at around 20 μm. The aerogel exhibits excellent elastic property under compression cycling test. Moreover, it displays good adsorption properties over many kinds of organic solvents, as well as excellent cycling adsorption property.