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Titel: Formation and hydrolytic stability of oxygen bridged heterometal bonds (Si-O-Ti, Si-O-Zr, Si-O-Ta) in sol-gel materials
Verfasser: Nacken, Manfred
Hoebbel, Dagobert
Schmidt, Helmut K.
Sprache: Englisch
Erscheinungsjahr: 1999
Quelle: Organic/inorganic hybrid materials II : symposium held April 5 - 9, 1999, San Francisco, California, U.S.A. / ed.: Lisa C. Klein ... - Warrendale, Pa. : Materials Research Society, 1999. — (Materials Research Society symposium proceedings ; 576), S. 221-226
SWD-Schlagwörter: Sauerstoff
Polymere
Homogenität
Alkoholate
DDC-Sachgruppe: 620 Ingenieurwissenschaften und Maschinenbau
Dokumentart : InProceedings (Aufsatz / Paper einer Konferenz etc.)
Kurzfassung: Glycidoxypropyltrimethoxysilane (GPTS) and metal alkoxides are frequently used in preparation of heterometal hybrid polymers and find application e. g. as contact lens materials and hard coatings on polymers. Such materials require a high homogeneity of the structural unit at the molecular level, which is supported by the formation of oxygen bridged heterometal bonds and their hydrolytic stability. By means of 29Si and 17O NMR the formation of heterometal bonds like Si-O-Ti, Si-O-Zr, Si-O-Ta was evidenced in GPTS-hydrolysates with Ti(OEt)4), Ti(OEt)3AcAc, Zr(OBun)4, Zr(OBun)3AcAc, Ta(OEt)5 or Ta(OEt)4AcAc (AcAc = acetylacetone ligand) as additives. Signals of heterometal bonds can be detected in 17O NMR spectra in the range of 170 to 350 ppm and are characterized in 29Si NMR spectra by defined chemical shifts to low (Si-O-Ta) and high magnetic fields (Si-O-Ti, Si-O-Zr) in comparison with signals of Si-O-Si bonds. The use of AcAc modified metal alkoxides leads to well resolved 29Si NMR spectra, which make the distinction between homo- and heterocondensed species easier. The addition of water to the sols (2 H2O / alkoxy group) leads to a degradation of heterometal bonds in favour of more homocondensed species, which reduces the homogeneity of such hybrid materials at the molecular level.
Link zu diesem Datensatz: urn:nbn:de:bsz:291-scidok-29371
hdl:20.500.11880/24685
http://dx.doi.org/10.22028/D291-24629
ISBN der Druckausgabe: 1-558-99483-1
SciDok-Publikation: 26-Aug-2010
Fakultät: Sonstige Einrichtungen
Fachrichtung: SE - INM Leibniz-Institut für Neue Materialien
Fakultät / Institution:INM
SE - Sonstige Einrichtungen

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