Organo-modified silica aerogels and implications for material hydrophobicity and mechanical properties

Two types of organo-modified silica gels, with the organic groups trimethoxymethylsilane (TRIMOS) and 3-(trimethoxysilyl)propyl methacrylate (TMSPMA), have been synthesized. The wet gels were dried by supercritical evacuation of the solvent. The materials with enhanced performance were those hybridized with TRIMOS and dried above the critical conditions of methanol. Such aerogels were found to be hydrophobic with mechanically improved properties whilst still maintaining the characteristic transparency of pure silica aerogels. The condensation degree and the number of superficial hydroxyl groups were determined from solid-state 29Si-NMR spectroscopy. Mechanical properties were measured using nanoindentation.