Abstract
We report on the results of 29Si NMR monitoring of alkoxysilane/ethanol/acid water sol-gels with tetraethoxysilane (TEOS), methyltriethoxysilane (MTEOS) and vinyltriethoxysilane (VTEOS). The gel time of the TEOS solution was 49 days at the degree of condensation c = 0.81, whereas MTEOS and VTEOS do not gel in spite of the high c = 0.95 achieved. The polymerization kinetics progressively slows with the time owing to the growth of sterical restrictions. To account for the effect we developed a kinetic model based on the reaction rates which explicitly decay as a function of the degree of condensation. The model describes the complete sol-gel process in all the studied systems including a gel transition in TEOS and aging of the gel.
Original language | English (US) |
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Pages (from-to) | 197-200 |
Number of pages | 4 |
Journal | Materials Science and Engineering B |
Volume | 37 |
Issue number | 1-3 |
DOIs | |
State | Published - Feb 1996 |
Externally published | Yes |
Keywords
- Alkoxysilanes
- Models of chemical kinetics
- Nuclear magnetic resonance
- Sol-gels
ASJC Scopus subject areas
- General Materials Science
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering