Conclusions
Regarding the considerable research effort devoted in the
beginning of the sol-gel adventure on solving the monolithic problem
for making bulk glass, George Scherer and Jeff Brinker, authors of
the first book on sol-gel, made
the following comment.
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"This is a bit ironic in retrospect, as it is evident that monoliths are the least technologically important of the potential applications of the gels. However, the allure of a room-temperature process for the preparation of bricks and windows was irresistible for research directors around the world, and
enormous effort has been devoted to demonstrating that that objective is nonsense".
It is obvious today that this initial
"nonsense" research effort, essentially conducted by glass researchers and
material scientists, and the breakthrough of making a
monolithic piece of silica glass of appreciable size at
1100°C, considerably helps the development of the technique and
its widespread to other scientific disciplines . This effort tremendously
increase the fundamental understanding of sol-gel chemistry,
drying and consolidation techniques.
It helped bring together physicists, solid state chemists, glass and ceramic scientists, and prepared the basements of
a versatile materials chemistry. and naturally oriented the
technique in areas where it makes sense to use it. Materials nano-manufacturing, films,
new organic-inorganic hybrids, nanocomposites, morphologically and structurally tailored
nanoparticles.
It doesn't prevent people of still continuing to improve sol-gel process in
more traditional areas like glass or ceramics.
Today monolithic gels can be made without the need of hypercritical
drying and converted to useful materials.
Lucent researchers achieved what was considered impossible 25 years
ago; produce meter size monoliths which can be densified to pure silica
glass and used as clad material for today optical fibers.
| REFERENCES |
- M. Yamane, S. Aso, T. Sakaino, J. of Mater. Sci., Vol 13,
1978, 865
- B.E. Yoldas, J. of Mater. Sci., Vol 10, 1975, 1856
- Synthesis of monolithic silica
gels by hypercritical solvent evacuation
M. Prassas, J. Phalippou, J. Zarzycki, J. of Mat. Sci. Vol 19,
1984, 1656
- Glasses from aerogels Part 1: The
synthesis of monolithic silica aerogels
J. Phalippou, T. Woignier, M. Prassas, J. of Mat. Sci. Vol 25,
1990, 3111
- Glasses from aerogels Part 2 : The
aerogel-glass transformation
T. Woignier, J. Phalippou, M. Prassas, J. of Mat. Sci. Vol 25,
1990, 3118
- G.A. Nicolaon et S.J. Teichner,
Bull. Soc. Chem. Fr, 1968, 1906
BOOKS
- Sol-Gel
Technology for Thin Films, Fibers, Preforms, Electronics, and Specialty Shapes
(Materials Science and Process Technology Series)
by Lisa C. Klein (Editor) (April 1988)Sol-Gel Science :
The Physics and Chemistry of Sol-Gel Processing
by C. Jeffrey Brinker, George W. Scherer (May 1990)
- Introduction to Sol-Gel
Processing
by Alain C. Pierre. (June 1998)
- Sol-Gel Optics
Processing and Applications
(Kluwer International Series in Engineering and Computer Science, No 259)
by Lisa C. Klein (Editor) (January 1994)
- Sol-Gel
Materials
Chemistry and Applications 
John. D. Wright, University
of Kent, Canterbury,UK and Nico A. J. M. Sommerdijk, Eindhoven
University of Technology, The Netherlands
Gordon and Breach Science Publishers (2001)
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