Microstructure and Adsorption Properties of MTMS / TEOS Co-precursor Silica Aerogels Dried at Ambient Pressure

Abstract

The existing preparation processes of silica aerogels suffer several problems, such as high cost, long preparation period and unsatisfactory performance. Herein a novel methyltrimethoxysilane (MTMS)/tetraethoxysilane (TEOS) co-precursor silica aerogel was prepared by using the ambient pressure drying method with MTMS/TEOS as co-precursor and water as solvent. The effects of MTMS and TEOS molar ratios on the performance of silica aerogels were investigated by using SEM and TG-DSC etc. The results indicated that with the increase of TEOS content in co-precursor, the gelation time of silica aerogel increased from 11 min to 38 min, and the density increased from 0.08018 g·cm−3 to 0.3499 g·cm−3, and the porosity decreased from 96.36% to 84.10%. In addition, the particle and pore sizes of the silica aerogel decreased gradually, and the whole structure became denser. The maximum surface area and porosity were found to be 913 m2·g−1 and 96.36% at a molar ratio of MTMS to TEOS of 1:9. In this case, the adsorption rates of this silica aerogel towards organic matters were the fastest and the adsorption rates for epoxy resin, silicone oil, methanol, ethanol and hexane were 12.00 g/g, 10.86 g/g, 10.23g/g, 9.83 g/g and 6.48 g/g, respectively. Moreover, the thermal stability of silicon aerogel also increased from 280.34 °C to 331.31 °C with the increase of TEOS content.