Hostname: page-component-78c5997874-lj6df Total loading time: 0 Render date: 2024-11-02T23:33:56.305Z Has data issue: false hasContentIssue false
  • English
  • Français

Possible Causes of the Change of Dynamics in Glass-Forming Materials Subjected to Reduced Dimension

Published online by Cambridge University Press:  10 February 2011

K. L. Ngai  and
A. K. Rizos
K. L. Ngai
Affiliation:
Naval Research Laboratory, Washington, DC 20375–5320USA, [email protected]
A. K. Rizos
Affiliation:
Department of Chemistry, University of Crete, and Foundation for Research & Technology-Hellas (FORTH), P.O. Box 1527, Heraklion 71409, Crete, Greece, [email protected]
Get access

Abstract

There is currently many ongoing investigations of the change in the glass transition temperature when a material is reduced in dimension from the normal bulk state. The reduction in dimension can be accomplished by casting the material as thin films with or without a substrate or putting it in nanometer size pores. In this work, we explore possible causes of the change in dynamics of the bulk material when the glass-former is subjected to such modifications. The existence of a growing cooperative length scale L(T) with decreasing temperature in bulk fragile glass-forming liquids reaching the size of approximately 1.5–2.0 nm at the glass transition temperature is the basis of our consideration. When the reduced dimension is comparable to L(Tg), cooperative dynamics within a lengthscale equal to L(Tg) can no longer be maintained in all three dimensions throughout the sample. The imposed reduction of the cooperative length scale speeds up the dynamics and causes a reduction of the glass transition temperature. For polymeric glass-formers particularly at higher molecular weights, reduction of one dimension in thin films engenders orientation of the polymer chains when their radius of gyration becomes comparable to the film thickness. The latter is known to cause also a reduction of the glass transition temeperature.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 455: Symposium T – Glasses and Glass Formers–Current Issues , 1996 , 147
Copyright
Copyright © Materials Research Society 1997

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Ngai, K.L., Comments Solid State Phys. 9, 121 (1979).Google Scholar
2. Ngai, K.L. in Disorder Effects on Relaxational Properties, edited by Richert, R. and Blumen, A. (Springer, Berlin 1994), p. 89–150.Google Scholar
3. Tsang, K.Y. and Ngai, K.L. Physical Review E 54, R3067 (1996).Google Scholar
4. Ngai, K.L., Roland, C.M. and Yee, A.F., Rubb. Chem. Tech. 66, 817 (1993).Google Scholar
5. Schmidt-Rohr, K., Phys. Rev. Letters 66, 3020 (1991).Google Scholar
6. Böhmer, R., Ngai, K.L., Angeli, C.A. and Plazek, D.J., J. Chem. Phys. 94, 3018 (1994).Google Scholar
7. Ferry, J.D., Viscoelastic Properties of Polymers. (Academic, New York) 3rd ed. (1980).Google Scholar
8. Gibbs, J.H. and DiMarzio, E.A., J. Chem. Phys. 43, 139 (1965).Google Scholar
9. Adam, G. and Gibbs, J.H., J. Chem. Phys. 28, 373 (1958).Google Scholar
10. Patkowski, A. et al. to be published.Google Scholar
11. Forrest, J.A., Dalnoki-Veress, K., Stevens, J.R. and Dutcher, J.R., Phys. Rev. Lett. 77, 2002 (1996).Google Scholar
12. Yee, A.F. and Gidley, D., private communication.Google Scholar
13. Ngai, K.L., Colmenero, J., Arbe, A., and Alegria, A., Macromolecules 25, 6727 (1992).Google Scholar
14. Donth, E., J. Non-Cryst. Solids 131–133, 204(1991).Google Scholar
15. Rizos, A.K. and Ngai, K.L., in this Volume.Google Scholar