Advertisement

Journal of Sol-Gel Science and Technology

, Volume 35, Issue 2, pp 99–105 | Cite as

Nanoengineered Silica-Polymer Composite Aerogels with No Need for Supercritical Fluid Drying

  • Nicholas Leventis
  • Anna Palczer
  • Linda McCorkle
  • Guohui Zhang
  • Chariklia Sotiriou-Leventis
Article

Abstract

Owing to their low density, dielectric constant, thermal conductivity, high porosity and chemical inertness, monolithic aerogels could be useful in a variety of electronic, optical and chemical applications [1]. However, practical implementation has been slow, because aerogels are fragile, environmentally sensitive (hydrophilic) and most importantly, the final stage of their preparation involves supercritical fluid (SCF) extraction [1c]. It is reported herewith that for a nominal 3-fold increase in density, typical polymer crosslinked silica aerogels are not only stronger (> 300×) and less hydrophilic (< 10×) than the underlying silica backbone, but they can also withstand the capillary forces exerted upon their nanostructured framework by the residing meniscus of selected solvents, and thus they can be dried under ambient pressure without need for supercritical fluid (SCF) extraction. The best solvent identified for that purpose is pentane, and the resulting aerogels are both microscopically and macroscopically identical to their SCF-CO2 dried counterparts. Being able to dry monolithic crosslinked aerogels without SCF extraction is expected to facilitate their commercial application.

Keywords

aerogel crosslinked composite ambient pressure drying 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    (a) C.A. Morris, M.L. Anderson, R.M. Stroud, C.I. Merzbacher, and D.R. Rolison, Science 284 622 (1999). (b) N. Hüsing and U. Schubert, Angew. Chem., Int. Ed. Engl. 37 22–45 (1998). (c) A.C. Pierre and G.M. Pajonk, Chem. Rev. 102 4243 (2002).Google Scholar
  2. 2.
    A.M. Thayer in Chemical & Engineering News, September 1, 2003 issue, p. 15.Google Scholar
  3. 3.
    (a) Y. Chen and J.O. Iroh, Chem. Mater. 11 1218 (1999). (b) Z. Ahmad and J.E. Mark, Chem. Mater. 13 3320 (2001).Google Scholar
  4. 4.
    S. Campbell and D. Scheiman, High Performance Polymers 14 17 (2002).CrossRefGoogle Scholar
  5. 5.
    C.A. Mitchell, J.L. Bahr, S. Arepalli, J.M. Tour, and R. Krishnamoorti, Macromolecules 35 8825 (2002).CrossRefGoogle Scholar
  6. 6.
    D. Rolison, Science 299 1698 (2003).CrossRefPubMedGoogle Scholar
  7. 7.
    (a) N. Leventis, C. Sotiriou-Leventis, G. Zhang, and A.-M.M. Rawashdeh, Nano Lett. 2 957 (2002). (b) G. Zhang, A.-M.M. Rawashdeh, C. Sotiriou-Leventis, and N. Leventis, Polymer Preprints 44 35 (2003). (c) M.F. Bertino, J.F. Hund, G. Zhang, C. Sotiriou-Leventis, A.T. Tokuhiro, and N. Leventis, J. Sol-Gel Sci. Tech. 30 43 2004. (d) G. Zhang, A. Dass, A.-M.M. Rawashdeh, J. Thomas, J.A. Counsil, C. Sotiriou-Leventis, E.F. Fabrizio, F. Ilhan, P. Vassilaras, D.A. Scheiman, L. McCorkle, A. Palczer, J.C. Johnston, M.A. B. Meador, and N. Leventis, J. Non-Cryst. Solids 350 152 (2004).Google Scholar
  8. 8.
    (a) J. Fricke, Sci. Am. 92 (1998 March). (b) H.D. Gesser and P.C. Goswami, Chem. Rev. 89 765 (1989).Google Scholar
  9. 9.
    N. Leventis, I.A. Elder, D.R. Rolison, M.L. Anderson, and C. Merzbacher, Chem. Mater. 11 2837 (1999).CrossRefGoogle Scholar
  10. 10.
    S.S. Prakash, C.J. Brinker, A.J. Hurd, and S.M. Rao, Nature 374 439 (1995).CrossRefGoogle Scholar
  11. 11.
    S.S. Prakash, C.J. Brinker, and A.J. Hurd, J. Non-Cryst. Solids 190 264 (1995).CrossRefGoogle Scholar
  12. 12.
    J.E. Fesmire, S.D. Augustynowicz, and S. Rouanet, Advances in Cryogenic Engineering 47(A), 1541 (2002) (Proceedings of the Cryogenics Engineering Conference, Madison, WI 2001; American Institute of Physics Conference Proceedings Vol. 613.)Google Scholar
  13. 13.
    (a) D.R. Rolison, and B. Dunn, J. Mater. Chem., 11 963 2001. (b) J.W. Long, R.M. Stroud, and D.R. Rolison, J. Non-Crystal. Solids 285 288 2001. (c) J.H. Harreld, W. Dong, and B. Dunn, MRS Bull. 33 561 (1998).Google Scholar
  14. 14.
    Drying our native wet gels from pentane under ambient pressure yields ambigels with BET surface areas ~890 m2 g−1 and average pore diameters ~10.1 nm. Drying native wet gels from acetone under ambient pressure yields xerogels with BET surface areas ~460 m2 g−1 and average pore diameters ~3.4 nm. (For the corresponding values of our native silica aerogels see foonote ‘a,’ Table 2.)Google Scholar
  15. 15.
    According to the literature, the rupture strength of silica aerogels, σ, follows a power law dependence on their density, ρ, according to σ = ρ2.6 ± 0.2 [16]. Given that the density of the underlying silica framework of all our samples is 0.18 ± 0.02 g cm−3, and the fact that all crosslinked aerogels of Table 2 and Fig. 4 are ~3.1 times more dense than plain silica, then, if the latter were made of plain silica, they would be expected to be only about 20 times stronger than the underlying silica framework. Denser plain silica aerogels have higher connectivity, i.e., more particles and more interparticle contacts; they do not necessarily have wider interparticle necks, in analogy to polymer crosslinked aerogels.Google Scholar
  16. 16.
    T. Woignier, J. Reynes, A. Hafidi Alaoui, I. Beurroies, and J. Phalippou, J. Non-Cryst. Solids 241 45 1998. (b) T. Woignier and J. Phalippou, Revue de Physique Appliquee 24 179 (1989).Google Scholar

Copyright information

© Springer Science + Business Media, Inc. 2005

Authors and Affiliations

  • Nicholas Leventis
    • 1
  • Anna Palczer
    • 1
  • Linda McCorkle
    • 1
  • Guohui Zhang
    • 2
  • Chariklia Sotiriou-Leventis
    • 2
  1. 1.Materials Division/Polymers BranchNASA Glenn Research CenterCleveland
  2. 2.Department of ChemistryUniversity of Missouri-RollaRolla

Personalised recommendations