Synthesis of Mesoporous Silica Aerogels via Ambient Pressure Drying

Using cheap waterglass as silica source, silica aerogels were synthesized via a novel fast ambient drying by using EtOH / TMCS / Heptane solution for modification of the wet gel. One-step solvent exchange and surface modification of wet gel were accomplished by reaction of trimethylchlorosilane (TMCS) with ethanol, pore water and Si-OH group in the wet gel. The synthesized silica aerogel was a light and crack-free solid, with a density of 0.128~0.136 g·cm-3 and porosity of 93.8%~94.2%. The microstructure, morphology and properties of the aerogels were studied by FTIR, SEM, TEM and BET measurement. The results indicate that silica aerogels exhibit a sponge structure with narrow particle and pore size distribution. The specific surface area of silica aerogels is in the range of 559~618 m2·g-1. Strong hydrophobicity is the characteristics of silica aerogel, and there is obvious Si-CH3 group on the surface of silica aerogel.