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Pore Structure Evolution of Silica Gel during Aging/ drying: Effect of Surface Tension

Published online by Cambridge University Press:  25 February 2011

Ravindra Deshpande ,
Douglas M. Smith  and
C. Jeffrey Brinker
Ravindra Deshpande
Affiliation:
UNM/NSF Center for Micro-Engineered Ceramics, University of Now Mexico, Albuquerque NM 87131, USA.
Douglas M. Smith
Affiliation:
UNM/NSF Center for Micro-Engineered Ceramics, University of Now Mexico, Albuquerque NM 87131, USA.
C. Jeffrey Brinker
Affiliation:
UNM/NSF Center for Micro-Engineered Ceramics, University of Now Mexico, Albuquerque NM 87131, USA.
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Abstract

Two-step acid/base (B2) and acid/acid (A2) catalyzed silica gels have been aged in ethanol or water baths followed by various aprotic solvents with a range of surface tensions. The physical and chemical structures of xerogels dried from these aprotic solvents were studied by a series of techniques (nitrogen adsorption, elemental analysis, TGA, SAXS)and compared to the corresponding structures of low temperature (CO2) and high temperature (ethanol) aerogels. The aprotic solvents help to isolate the effects of pore fluid surface tension during drying since they do not react with the gel surface. B2 xerogels showed a linear decrease in surface area with increasing surface tension. Pore volume and pore size followed a similar trend. Micropore analysis on A2 xerogels showed an increase in micropore volume and surface area with increase in surface tension, whereas total surface area and pore volume showed an opposite trend. Thus, by varying surface tension and aging, one is able to independently control surface area, pore volume, and pore size.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 271: Symposium N – Better Ceramics Through Chemistry V , 1992 , 553
Copyright
Copyright © Materials Research Society 1992

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References

REFERENCES

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