Abstract
The effect of various solvents and catalysts on the monolithicity and physical properties of silica aerogels is reported. The aerogels were prepared by hydrolysis and polycondensation of tetramethoxysilane, followed by hypercritical drying, using 6 solvents of different chain lengths, and 17 catalysts consisting of strong and weak acids, bases and their mixtures. It was found that solvents of longer chain lengths and strong basic catalysts resulted in semitransparent to opaque aerogels, whereas strong acids and their combinations with a weak basic catalyst produced transparent but cracked aerogels. While weak acids and their combinations with a weak base were found to produce shrunk and semitransparent (opaque for CH3COOH + NH4OH) aerogels, the best quality transparent, monolithic, low-density and refractive index, and large surface area aerogels were obtained for a combination of weak basic catalysts and solvents of shorter branching and chain lengths. The physical properties of the aerogels were studied by BET analysis, porosity, density, refractive index and optical transmission measurements.
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H. D. Gesser and P. C. Goswami, Chem. Rev, 89 (1989) 765.
J. Fricke, Sci. Am. (1988) 92.
J. Fricke and G. Reidienauer, J. Non-Cryst. Solids 95, 96 (1987) 1135.
U. Heinemann, E. Hummer, D. Biittner, R. Caps and J. Fricke, High Temp. High Press. 18 (1986) 517.
D. Buttner and J. Fricke, Int. J. Solar Energy 3 (1985) 89.
A. Beck, R. Caps and J. Fricke, J. Phys. D Appl. Phys. 22 (1989) 730.
R. Caps and J. Fricke, Solar Energy 36 (1986) 361.
P. Scheuerpflug, R. Caps, D. Buttner and J. Fricke, Int. J. Heat Mass Transfer 28 (1985) 2299.
J. Fricke and A. Emmerling, Struct. Bond. 77 (1992) 37.
D. Buttner, R. Caps and J. Fricke, High Temp. High Press. 17 (1985) 375.
R. L. Guyer and D. E. Koshland Jr., Science 250 (1990) 1642.
S. S. Kistler and A. G. Caldwell, Ind. Eng. Chem. 26 (1934) 658.
S. S. Kistler, J. Phys. Chem. 42 (1942) 19.
J. F. White, Ind. Eng. Chem. 31 (1939) 827.
M. Cantin, M. Casse, L. Koch, R. Jouan, P. Mestreau, D. Roussel, F. Bonnin, J. Moutel and S. J. Teichner, Nucl. Instrum. Meth. 118 (1974) 177.
M. Bourdinaud, J. B. Cheze and J. C. Thevenin, ibid. 136 (1976) 99.
P. J. Carlson, K. E. Johansson, J. Kesteman, J. Norsby, O. Pingot, S. Tavernier, F. Van den Bogaert and L. van Lancker, ibid. 160 (1979) 407.
H. Burkhardt, P. Koehler, R. Riethmuller, B. H. Wük, R. Fohrmann, J. Franzke, H. L. Krosemann, R. Maschuur, G. Poelz, J. Reichardt, J. Ringel, O. Romer, R. Rusch, F. Schmuser, R. van Staa, J. Freeman, P. Leconte, T. Meyer, S. L. Wu and G. Zokernig, ibid. 184 (1981) 319.
N. K. Kim, K. Kim, D. A. Payne and R. S. Upadhye, J. Vac. Sci. Technol. A7 (1989) 181.
K. Y. Jang, K. Kim and R. S. Upadhye, ibid. A8 (1990) 1732.
K. Kim, K. Y. Jang and R. S. Upadhye, J. Am. Ceram. Soc. 74 (1991) 1987.
S. J. Teichner, G. A. Nicolaon, M. A. Vicarini and G. E. E. Gar Des, Adv. Coll. Interf. Sci. 5 (1976) 245.
D. Maret, G. M. Pajonk and S. J. Teichner, in “Catalysis on the Energy Scene”, edited by S. Kaliaguine and A. Mahay (Elsevier Science, Amsterdam 1984) p. 347.
G. M. Pajonk, Appl. Catal. 72 (1991) 217.
J. Fricke, M. C. Arduini-Schuster, D. Büttner, H. P. Ebert, U. Heinemann, J. Hetfleisch, E. Hummer, J. Kuhn and X. Lu, in “21st International Thermal Conductivity Conference”, 15–18 October 1989, Lexington, Kentucky.
A. J. Hunt, Lawrence Berkeley Laboratory, University of California, “LBL Research Review”, Summer 1991, p. 3.
C. S. Ashley, S. T. Read, C. J. Brinker, R. J. Walko, R. E. Ellefson and J. T. Gill, in “Sol-Gel Optics”, edited by J. D. Mackenzie and D. R. Ubrich, proc. SPIE 1328 (1990) 220. (SPIE, Washington, 1990.)
S. S. Kistler, Nature 127 (1931) 741.
Idem, J. Phys. Chem. 36 (1932) 52.
G. A. Nicolaon and S. J. Teichner, Bull. Soc. Chim. Fr. 5 (1968) 1900.
J. Zarzycki, M. Prassas and J. Phalippou, J. Mater. Sci. 17 (1982) 3371.
J. Fricke (ed.), “Aerogels” (Springer, Berlin, 1986).
T. M. Tillotron and L. W. Hrubesh, Mater. Res. Soc. Symp. Proc. 180 (1990) 309.
A. Venkateswara Rao and N. N. Parvathy, J. Mater. Sci. 28 (1993) 3021.
S. Henning and L. Svensson, Phys. Scripta 23 (1981) 699.
G. Poelz and R. Riethmuller, Nucl. Instrum. Meth. 195 (1982) 491.
M. Prassas, J. Phalippou and J. Zarzycki, J. Mater. Sci. 19 (1984) 1656.
J. G. Van Lierop, A. Huizing, W. C. P. M. Meerman and C. A. M. Mulder, J. Non-Cryst. Solids 82 (1986) 265.
R. A. Laudise and D. W. Johnson Jr, ibid. 79 (1986) 155.
C. J. Brinker and G. W. Scherer, “Sol-Gel Science” (Academic Press, Boston, 1990).
L. L. Hench and J. K. West, Chem. Rev. 90 (1990) 33.
S. G. Gregg and K. S. W. Sing, “Adsorption, Surface Area and Porosity” (Academic Press, London, 1982).
S. Brunauer, P. H. Emmert and E. Teller, J. Am. Chem. Soc. 62 (1940) 1723.
W. G. Klemperer and S. D. Ramamurthi, Mater. Res. Soc. Symp. Proc. 121 (1988) 5.
V. Belot, R. Corriu, C. Guerin, B. Henner, D. Leclercq, H. Mutin, A. Vioux and Q. Wang, ibid. 180 (1990) 3.
G. Hoang, J. Watson and T. W. Zerda, ibid 180 (1990) 15.
M. G. Voronkov, V. P. Mileshkevich and Y. A. Yuzhelevski, “The Siloxane Bond” (Consultants Bureau, New York, 1978).
M. G. Voronkov and S. V. Barenko, Sov. Sci. Rev. B. Chem. 15 (1990) 1.
J. S. Kirk, US Pat. 2408 654-2408 656, Du Pont (1946).
R. K. Iler, J. Phys. Chem. 56 (1952) 673.
C. J. Brinker, W. D. Drotning and G. W. Scherer, Mater. Res. Soc. Symp. Proc. 32 (1984) 25.
R. K. Iler, “The Chemistry of Silica”, (Wiley, New York, 1979).
T. L. Brown and H. E. Le May Jr, “Chemistry: The Central Science”, 4th Edn (Prentice-Hall International, New York, 1990).
D. W. Schaefer and K. D. Keefer, Phys. Rev. Lett. 53 (1984) 1383.
L. W. Kelts, N. J. Effinger and S. M. Melpolder, J. Non-Cryst. Solids 83 (1986) 353.
D. W. Schaefer, C. J. Brinker, J. P. Wilcoxon, D. O. Wu, J. C. Phillips and B. Chu, Mater. Res. Soc. Symp. Proc. 121 (1988) 691.
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Venkateswara Rao, A., Pajonk, G.M. & Parvathy, N.N. Effect of solvents and catalysts on monolithicity and physical properties of silica aerogels. JOURNAL OF MATERIALS SCIENCE 29, 1807–1817 (1994). https://doi.org/10.1007/BF00351300
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DOI: https://doi.org/10.1007/BF00351300