Journal of Porous Materials

, Volume 16, Issue 1, pp 101–108 | Cite as

Synthesis and characterization of low density and hydrophobic silica aerogels dried at ambient pressure using sodium silicate precursor

  • Poonam M. Shewale
  • A. Venkateswara Rao
  • Jyoti L. Gurav
  • A. Parvathy Rao


The present paper deals with the synthesis and characterization of low density and hydrophobic silica aerogels dried at ambient pressure using low cost sodium silicate precursor. The hydrogels were prepared by sol–gel processing of sodium silicate precursor and acetic acid catalyzed water followed by vapour passing and solvent exchange with methanol. The mixture of MeOH:trimethylchlorosilane (TMCS):hexane was used for the end capping of the silanols present on the silica surface. The process was optimized by varying vapour passing time, gel ageing time, molar ratios of H2O/Na2SiO3, CH3COOH/Na2SiO3 and TMCS/Na2SiO3 and silylation period. The aerogels have been characterized by bulk density, % of volume shrinkage, porosity, Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analysis and contact angle measurements. The best quality silica aerogels in terms of low density (0.073 g/cc), higher porosity (96%) and better hydrophobicity (θ = 146°) have been obtained with the molar ratio of Na2SiO3:H2O:CH3COOH:TMCS at 1:166.6:2.25:11.9.


Aerogels Hydrophobicity Contact angle Optical transmission Ambient pressure drying 



The authors are grateful to the Condensed Matter Advisory Committee, Department of Science and Technology (DST), New Delhi, Government of India, for the financial support for this work through a major research project on “Aerogels” (No. SR/S2/CMP-67/2006). Dr. A. Parvathy Rao is highly thankful to the DST for the Senior Research Associateship.


  1. 1.
    L.W. Hrubesh, Chem. Ind. 17, 824 (1990)Google Scholar
  2. 2.
    G.C. Bond, S. Flamerz, A. Emmerling, Appl. Catal. 33, 219 (1987)CrossRefGoogle Scholar
  3. 3.
    J. Fricke, A. Emmerling, Struct. Bond. 77, 27 (1992)Google Scholar
  4. 4.
    C.A.M. Mulder, J.G. Van Lierop, in Aerogels, ed. by J. Fricke (Springer, Berlin, 1986), p. 68Google Scholar
  5. 5.
    S. Svendson, J. Non-Cryst. Solids 145, 240 (1992)CrossRefGoogle Scholar
  6. 6.
    V. Wittwer, J. Non-Cryst. Solids 145, 233 (1992)CrossRefGoogle Scholar
  7. 7.
    Z. Deng, J. Wang, A. Wu, J. Shen, B. Zhou, J. Non-Cryst. Solids 225, 101 (1998)CrossRefGoogle Scholar
  8. 8.
    F. Schwertfeger, D. Frank, M. Schmidt, J. Non-Cryst. Solids 225, 24 (1998)CrossRefGoogle Scholar
  9. 9.
    A.P. Rao, A.V. Rao, G.M. Pajonk, Appl. Surf. Sci. 253, 6032 (2007)CrossRefGoogle Scholar
  10. 10.
    A.P. Rao, A.V. Rao, G.M. Pajonk, P.M. Shewale, J. Mater. Sci. 42, 8418 (2007)CrossRefGoogle Scholar
  11. 11.
    A.P. Rao, G.M. Pajonk, A.V. Rao, J. Mater. Sci. 40, 3481 (2005)CrossRefGoogle Scholar
  12. 12.
    J.J. Bikerman, Surface Chemistry: Theory and Applications, 2nd edn. (Academic, New York, 1958), p. 343Google Scholar
  13. 13.
    G. Reichenaver, J. Non-cryst. Solids 350, 3482 (2004)Google Scholar
  14. 14.
    A.E. Scheidegger, The Physics of Flow Through Porous Media, 3rd edn. (University of Torento Press, Torento, 1974)Google Scholar
  15. 15.
    C.J. Brinker G.W. Scherer, Sol–Gel Science (Academic, San Diego, 1990), p. 358Google Scholar
  16. 16.
    C.J. Brinker G.W. Scherer, Sol–Gel Science (Academic, San Diego, 1990), p. 105Google Scholar
  17. 17.
    A.V. Rao, M.M. Kulkarni, D.P. Amalnerkar, Tanay Seth, J. Non-Cryst. Solids 330, 190 (2003)Google Scholar
  18. 18.
    P.C. Heimenz, Principles of Colloid and Surface Chemistry (Marcel Dekkar, New York, 1977)Google Scholar
  19. 19.
    C.J. Lee, G.S. Kim, S.H. Hyun, J. Mater. Sci. 37, 2237 (2002)CrossRefGoogle Scholar
  20. 20.
    C.J. Pouchert (ed.) Aldrich Library of FTIR Spectra, vol 2 (Aldrich Chemical, Milwaukee, 1985)Google Scholar
  21. 21.
    M. Laczka, K. Cholewa-Kowalska, M. Kogul, J. Non-Cryst. Solids 287, 10 (2001)CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • Poonam M. Shewale
    • 1
  • A. Venkateswara Rao
    • 1
  • Jyoti L. Gurav
    • 1
  • A. Parvathy Rao
    • 1
  1. 1.Air Glass Laboratory, Department of PhysicsShivaji UniversityKolhapurIndia

Personalised recommendations