Rapid synthesis and characterization of ambient pressure dried monolithic silica aerogels in ethanol/water co-solvent system

In this paper, using methyltrimethoxysilane (MTMS) as precursor, silica aerogels (SA) with excellent performance were synthesized within 10 h via APD without further surface modification and solvent exchange. The investigation was concentrated on three primary factors, including base catalyst, surfactant , and co-solvent system. The results indicated that NH 3 ·H 2 O concentration and the volume ratio of NH 3 ·H 2 O to MTMS were of great importance to the formation of particles, clusters, and pores. It was also obtained that the surfactant of CTAB influences the pore structure as well as thermostability of prepared aerogels significantly. Furthermore, an optimum volume ratio of EtOH/H 2 O in co-solvent system not only reduced the volume shrinkage but also enabled a good hydrophobicity of prepared SAs. Base on above, by adjusting the preparation parameters, the obtained SAs can exhibit the low density of 0.0968 g/cm 3 , low thermal conductivity of 0.037 W m −1  K −1 , contact angle as high as 144.7 ° and thermostability reaching up to 528.1 °C. Meanwhile, some specific performance of SAs, such as hydrophobicity, could be tailored, which will improve its applicability.