J. Sjöblom, S. Friberg, A. Amran
1995
Citations
0
Influential Citations
6
Citations
Journal
Journal of Dispersion Science and Technology
Abstract
ABSTRACT The reaction between aluminum nitrate nonahydrate and tetraethoxysilane in ethanol was followed by NMR of the 29Si nucleus. The results showed the initial hydrolysis and condensation to be fast to an extent that no monomeric species of the silicon compounds were found after mixing for three minutes. In addition, the results showed the condensation reaction to be fast compared to the hydrolysis. This fact was demonstrated by the extremely high ratio of ethoxy groups to OH groups in the different specia (SiO)y Si(OH)x (OC2H5)4-x-y The reaction proceeded without added acid and gave gels of silica with colloidally dispersed aluminum nitrate. The protons to catalyze the reaction emanated from the hydrated aluminum salt; titration by sodium hydroxide revealed the hydrate to be a strong acid in ethanol with a titration point showing three moles of base per mole of aluminum salt.