Characterization of methyl-substituted silica gels with Si–H functionalities
- 1 January 1995
- journal article
- Published by Royal Society of Chemistry (RSC) in Journal of Materials Chemistry
- Vol. 5 (9) , 1363-1374
- https://doi.org/10.1039/jm9950501363
Abstract
Gels have been prepared via hydrolysis–condensation reactions of triethoxysilane (TREOS) and methyldiethoxysilane (MDES) in various ratios. The hydrolysis–condensation reactions of the precursors have been investigated by 29Si and 17O solution NMR. Both precursors present a very high reactivity towards hydrolysis and condensation reactions, and formation of co-condensed species will be discussed. These highly reactive precursors lead to transparent gels over a large composition range, 0.1 MDES:TREOS 10. Their structure was investigated by 29Si MAS NMR, FTIR and DSC: the gels appear as highly condensed homogeneous systems in which the difunctional and trifunctional units are randomly distributed. The microstructure of the gels was also investigated through the measurement of specific surface area and skeletal density. Finally, some physical properties have also been measured such as thermal stability in O2 and inert atmosphere (Ar), coefficient of thermal expansion (α) and elastic modulus (E).Keywords
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