Structural Analysis and Control of Ultralow Density Silica Aerogels Prepared by Sol-gel Process

In this paper, nano-porous silica aerogels were prepared via sol-gel process with acid/base two-step catalysis technique. Silica aerogel structure can be effectively controlled by changing experimental parameter. Ultralow density silica aerogel with density as low as 3.4 mg/cm3 has been successfully prepared. Transmission electron microscope (TEM), gas chromatography/mass spectrometry (GC/MS) and particle size analyzer were used to characterize the properties of the microstructure and particle distribution of the sol. Scanning electron microscope (SEM) was used to characterize the microstructure of the aerogels. Structure controlling by changing the catalysis condition during sol-gel process was researched, and stabilization of the sol during long-time reserving was researched too. The results showed that silica sol particle can be controlled from 4nm to 9nm continuously and the optimized refluxing time was about 24 hours