SOL-GEL SYNTHESIS OF AEROGELS

Experiment 1 consists of synthesizing a nanostructured material using sol-gel science. The process to form the final material requires a drying step, which includes either ambient drying or supercritical drying. The different drying procedures create what are known as aerogels or xerogels. Figure 1 shows different types of aerogels produced by authors: a semi-transparent low-density aerogel and a highly transparent, ultra-low density aerogel. Aerogels are very high surface area metal oxides that have been called frozen smoke due to their transparency and ultra-low densities. They are obtained by supercritical drying. Xerogels are a lower surface area version of aerogels and have a greater density relative to their aerogel form due to drying at ambient conditions. For experiment I, we have formulated the exact compositions that the students will synthesize for experiment I. This includes formation of a silicon oxide aerogel and xerogel. via hydrolysis and condensation of metal alkoxides.

The previous setup for supercritical drying aerogels is manual and too time intensive for the use by the student. For this reason, we are configuring a computer control supercritical drying unit: All of the components except control software and computer boards and two of the control valves are on hand. This unit is required, in order to form aerogels, once the sol-gel reaction is completed, the chemicals are "dried" using supercritical solvents. This will avoid deformation ("collapsing") under its own surface tension. Below, In Figure 2 is a diagram of the unit under construction.

Characterization of the aerogels. The aerogels and xerogels will be analyzed on an ASAP 2010 high surface area unit using physical adsorption of gases. Their mechanical properties will also be measure using new quartz equipment with a channel where laser light shines through to detect its porosity. Also TEM pictures can be taken with the TEM machine in Microbiology Lab (OU).