Flexible silica aerogels with super-hydrophobicity and elasticity were successfully prepared via acid-base two-step sol-gel method

followed by supercritical drying process. They were synthesized with tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) as coprecursors

methyl alcohol as solvent and cetyl trimethyl ammonium bromide (CTAB) as surfactant. The influence of acid-base catalysts concentration on silica aerogels was studied in detail. Aerogels prepared with higher base concentration and lower acid concentration were found to have more uniform pore structures and narrower pore size distributions. It was observed that the optimum aerogels can be obtained with 0.01 mol·L-1 oxalic acid and 5 mol·L-1 ammonia as acid-base catalysts

respectively. The density of the as-prepared aerogel was as low as 0.135 g·cm-3

the porosity was around 93% and the specific surface area was as high as 807 m2·g-1. The maximum compression ratio of the aerogel was as high as 60% with 100% compression resilience ratio.