Sol-gel synthesis of heterometallic oxopolymers
- Universite Pierre et Marie Curie, Paris (France)
Oxopolymers can be obtained via the hydrolysis and condensation of metal alkoxides M(OR){sub z}. The design of these molecular precursors by chemical modification provides a chemical control over the formation of condensed species. Depending on the hydrolysis ratio h=H{sub 2}O/M and the amount of complexing ligands x-X/M, molecular species, oxopolymers or colloidal particles can be obtained. More condensed species are obtained as x decreases and h increases. A major problem in forming homogeneous multicomponent gels is the unequal hydrolysis and condensation rates of the metal alkoxides which may result in chemical inhomogeneities. Several approaches have been attempted to overcome this problem, including partial prehydrolysis, matching of hydrolysis rates by chemical modification with chelating ligands and synthesis of double alkoxides. This paper discusses the formation of heterometallic alkoxides or oxo-alkoxides as precursors for heterometallic oxopolymers. Special attention will be given to silica based materials and the stability of Si-O-Ti or Si-O-Al bonds during the course of sol-gel chemistry.
- OSTI ID:
- 141602
- Report Number(s):
- CONF-930304--
- Country of Publication:
- United States
- Language:
- English
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