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Investigation of Hydrolysis and Condensation in Organically Modified Sol-Gel Systems: 29SI NMR and the INEPT Sequence†

Published online by Cambridge University Press:  10 February 2011

T. M. Alam ,
R. A. Assink  and
D. A. Loy
T. M. Alam
Affiliation:
Properties of Organic Materials, Sandia National Laboratories, Albuquerque, NM 87185-1407
R. A. Assink
Affiliation:
Properties of Organic Materials, Sandia National Laboratories, Albuquerque, NM 87185-1407
D. A. Loy
Affiliation:
Properties of Organic Materials, Sandia National Laboratories, Albuquerque, NM 87185-1407
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Abstract

The spectral editing properties of the 29Si NMR INEPT heteronuclear transfer experiment have been utilized for the identification and characterization of hydrolysis and initial condensation products in methyltrimethoxysilane (MTMS) sol-gel materials. 29Si NMR assignments in MTMS are complicated by a small spectral dispersion (∼0.5 ppm) and two different 29Si-1H J couplings. By using analytical expressions for the INEPT signal response with multiple heteronuclear J couplings, unambiguous spectral assignments can be made. For this organomethoxysilane the rate of hydrolysis was found to be very rapid and significantly faster than either the water- or alcohol-producing condensation reactions. The hydrolysis species of both the MTMS monomer and its initial T1 condensation products follow statistical distributions that can be directly related to the extent of the hydrolysis reactions. The role of the statistical distribution of hydrolysis products on the production and synthetic control of organically modified sol-gels is discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 435: Symposium V – Better Ceramics Through Chemistry VII , 1996 , 421
Copyright
Copyright © Materials Research Society 1996

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Footnotes

†

This work supported by the US Department of Energy under Contract DE-AC04-94AL85000.

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