Abstract.
We have used a sol-gel technique to obtain optically transparent hydrogels in which water is confined within a 3D silica matrix. In this work we report X-ray scattering and dielectric spectroscopy measurements on samples having different aging times and compare them with previously obtained results with near-infrared (NIR) absorption spectroscopy. X-ray scattering at room temperature enables to characterize the structure and size of the matrix pores and the non-uniform distribution of water inside the hydrogel. Broad band dielectric spectroscopy in the temperature range 130–280 K enables to study water dynamics. In aged hydrogels two relaxations are clearly evident and show characteristic temperature dependence. The faster relaxation has an Arrhenius behavior in the whole temperature range investigated with an activation enthalpy of ∼ 50 kJ/mol; it is attributed to water molecules strongly interacting with the silica matrix. The slower relaxation has a markedly non-Arrhenius behavior which can be fitted with a Vogel-Fulcher-Tamman (VFT) relation with critical temperature of ∼100 K and activation enthalpies of 35 and 95 kJ/mol at 300 and 170 K respectively; it is attributed to water molecules within the pores that do not interact strongly with the matrix and behave collectively. The VFT temperature dependence of the dielectric relaxation time suggests that this water does not crystallize, in agreement with previous results from NIR spectroscopy.
Similar content being viewed by others
References
1. W. Franks, Water: A Comprehensive Treatise, Vol. 7 (New York: Plenum Press, 1982)
2. G. Sartor, A. Hallbrucker, E. Mayer, Biophys. J. 69, 2679 (1995)
3. W. Doster, A. Bachleitner, R. Dunau, M. Hiebl, E. Lusher, Biophys. J. 50, 213 (1986)
4. M.A. Ricci, F. Bruni, A.K. Soper, J. Chem. Phys. 109, 1478 (1998)
5. R. Bergman, J. Swenson, Nature 403, 283 (2000)
6. G. Barut, P. Pissis, R. Pelster, G. Nimtz, Phys. Rev. Lett. 80, 3543 (1998)
7. A. Cupane, M. Levantino, M.G. Santangelo, J. Phys. Chem. B 106, 11323 (2002)
8. M.G. Santangelo, M. Levantino, E. Vitrano, A. Cupane, Biophys. Chem. 103, 67 (2003)
9. A.M. Venezia, V. La Parola, A. Longo, A. Martorana, J. Sol. State Chem. 161, 373 (2001)
10. O. Glatter, O. Kratky, Small Angle X-ray Scattering (New York: Academic Press, 1982)
11. C.J. Brinker, K.D. Keefer, D.W. Schaefer, R.A. Assink, B.K. Kay, C.S. Ashley, J. Non-Cryst. Solids 48, 45 (1984)
12. P.W. Schmidt in NATO Asi on Modern aspect of Small-Angle Scattering (H. Brumberger, The Netherlands: Kluwer Academic Publisher, 1994), p. 31–45
13. G. Deganello, L. Liotta, A. Longo, A. Martorana, Y. Yanev, N.A. Zotov, J. Non-Cryst. Solids 232, 547 (1998)
14. R.L. Mozzi, B.E. Warren, J. Appl. Cryst. 2, 164 (1969)
15. A.R. Drews, B.D. Thayer, H.J. Stapleton, G.C. Wagner, G. Giugliarelli, S. Cannistraro, Biophys. J. 57, 157 (1990)
16. J. Pescia, S.K. Misra, M. Zapirov, Phys. Rev. Lett. 83, 1866 (1999)
17. C.A. Angell, V. Rodgers, J. Chem. Phys. 80, 6245 (1984)
18. R.J. Speedy, C.A. Angell, J. Chem. Phys. 65, 851 (1976)
19. P. Gallo, F. Sciortino, P. Tartaglia, S.-H. Chen, Phys. Rev. Lett. 76, 2730 (1996)
20. F. Pizzitutti, F. Bruni, Rev. Sci. Instr. 72, 2502 (2001)
21. I.M. Hodge, J. Res. Natl. Stand. Technol. 102, 195 (1997)
22. C.A. Angell, J. Res. Natl. Stand. Technol. 102, 171 (1997)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Cammarata, M., Levantino, M., Cupane, A. et al. Structure and dynamics of water confined in silica hydrogels: X-ray scattering and dielectric spectroscopy studies. Eur. Phys. J. E 12 (Suppl 1), 63–66 (2003). https://doi.org/10.1140/epjed/e2003-01-016-2
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1140/epjed/e2003-01-016-2