Intramolecular condensation reactions of {alpha},{omega}-bis(triethoxysilyl)alkanes. Formation of cyclic disilsesquioxanes
Journal Article
·
· Journal of the American Chemical Society
- Sandia National Lab., Albuquerque, NM (United States)
- Univ. of California, Irvine, CA (United States)
In this paper, we used mass spectrometry and {sup 29}Si NMR spectroscopy to discover that the length of the alkylene-bridging groups had a pronounced effect on the competition between cyclization and polymerization of {alpha},{omega}-bis(triethoxysilyl)alkanes and on the formation of polymeric gels. While the intramolecular reaction clearly slows gelation, the cyclic disilsesquioxanes are still tetrafunctional monomers theoretically capable of forming polymeric gels. If the ring structures, which bear a striking resemblence to carbohydrates, are preserved through the polymerization, the resulting poly(cyclic disilsesquioxane) gels may have structural similarities to branched or cross-linked carbohydrates, such as cellulose or chitosan. Under base-catalyzed sol-gel polymerization conditions, 3 and 4 (six- and seven-membered cyclic disilsesquioxanes, respectively) quickly reacted to give gels with significant ring opening as determined from the {sup 29}Si chemical shifts in solid-state (CP MAS) NMR spectra. However, gels prepared under acidic conditions reveal some or all of the cyclic disilsesquioxane functionality was preserved in the polymers. 13 refs., 1 fig.
- Research Organization:
- Sandia National Laboratory
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 380900
- Journal Information:
- Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 35 Vol. 118; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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Cyclization Phenomena in the Sol-Gel Polymerization of a,w-Bis(triethoxysilyl)alkanes and Incorporation of the Cyclic Structures into Network Silsesquioxane Polymers
Journal Article
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Wed Jun 16 00:00:00 EDT 1999
· Journal of the American Chemical Society
·
OSTI ID:684323
Intramolecular condensation reactions of {alpha}, {omega}- bis(triethoxy-silyl)alkanes. Formation of cyclic disilsesquioxanes
Conference
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Thu Aug 01 00:00:00 EDT 1996
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OSTI ID:282006
Cyclization Phenomena in the Sol-Gel Polymerization of a,w-Bis(triethoxysilyl)alkanes and Incorporation of the Cyclic Structures into Network Silsesquioxane Polymers
Journal Article
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Sun Jan 03 23:00:00 EST 1999
· Journal of the Americna Chemical Society
·
OSTI ID:2884