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Structural Evolution During the Sol to Gel Transition of Silicon-Alkoxide Based Sols Observed by Cryogenic Transmission Electron Microscopy (CRYO-TEM)

Published online by Cambridge University Press:  25 February 2011

Joseph K. Bailey  and
Martha L. Mecartney
Joseph K. Bailey
Affiliation:
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455
Martha L. Mecartney
Affiliation:
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455
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Abstract

The gelation reaction for tetraethoxysilane in both acid and base catalyzed environments was studied using cryogenic transmission electron microscopy. The evolution of the gel structure was observed in wet samples by the technique of fast-freeze vitrification, in which the three dimensional gel structure is preserved in vitreous solvent. The sample is then observed in the electron microscope using a cold stage. Samples were prepared and allowed to react until a specific point of gelation was reached, then were vitrified at that point. Results from this technique show a coarse network structure for base catalyzed gels. This network is composed of silica clusters ≈40Å in size. The acid catalyzed gels show an extremely fine texture (<10Å) at end point of gelation. The structures at intermediate stages of gelation were also determined.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 121: Symposium H – Better Ceramics Through Chemistry III , 1988 , 367
Copyright
Copyright © Materials Research Society 1988

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References

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