I have found out how to make silica aerogel.
Currently, the solution that I need to create to make the gel requires tetramethyl orthosilicate or TMOS. Furthermore, the procedure requires me to make two solutions, one being a catalyst and mix the two.
What is the chemistry that goes on to form the ultra-light gel? How does the TMOS, methanol, and ammonium hydroxide interact with one another? What are possible substitutes for TMOS, that are less expensive?