THE PHASE-DIAGRAM WATER ETHANOL LONG-CHAIN ALCOHOLS AND GELS FROM HYDROLYZED TETRAETHOXYSILANE

The phase diagrams for water-ethanol-long chain alkanols were determined and the phase limits compared to the areas for transparent gels after hydrolysis and subsequent condensation of tetraethoxysilane. The results showed the phase equilibria at high water content to determine transparency of the gels, while at low water contents the ratio between water and the long chain alcohol was decisive. Addition of a hydrocarbon reduced the maximum water content for the transparent gels significantly because the minimum water content to cause phase separation was strongly decreased.