Hostname: page-component-76fb5796d-25wd4 Total loading time: 0 Render date: 2024-04-27T04:36:30.470Z Has data issue: false hasContentIssue false
  • English
  • Français

Influence of Confinement on Molecular Reorientational Dynamics of Liquid Crystals: Broadband Dielectric Spectroscopy Investigations

Published online by Cambridge University Press:  17 March 2011

Fouad M. Aliev
Fouad M. Aliev*
Affiliation:
Department of Physics, University of Piertp Rico, San Juan, PR 00931, USA
Get access

Abstract

Broadband dielectric spectroscopy has been applied for investigations of the dynamic behavior of liquid crystals (LCs) confined in porous matrices with random pores as well as in parallel cylindrical pores. We observed deep supercooling of LC in random pores. The relaxation times of the process due to the molecular rotation in deeply supercooled state are slower than at the temperatures corresponding to nematic phase by a factor of 106. This slowing down is accompanied by anomalous broadening of the dielectric spectra. For LC confined in cylindrical pores with homeotropic orientation on the pore walls we have investigated the relaxation of the librational mode. The dynamics of this mode is different from the behavior observed in investigations of relaxation due to reorientation of molecules around their short axis. The interpretation of the temperature dependencies of relaxation times of the librational mode needs the involvement of the temperature dependence of orientational order parameter. The investigations of the relaxation in thin LC layers formed on cylindrical pore walls show that the process due to rotation of molecules around their short axis (with single relaxation time for bulk LC) is the process with a distribution of relaxation times in thin layers and this process broadens with decreasing thickness of the layers.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 699: Symposium R – Electrically Based Microstructural Characterization III , 2001 , R7.4
Copyright
Copyright © Materials Research Society 2002

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

1. Cummins, P.G., Danmur, D.A., and Laidler, D.A., Mol. Cryst. Liq. Cryst. 30, 109 (1975).Google Scholar
2. Lippens, D., Parneix, J.P., and Chapoton, A., J. de Phys. 38, 1465 (1977).Google Scholar
3. Wacrenier, J.M., Druon, C., and Lippens, D., Mol. Phys. 43, 97 (1981).Google Scholar
4. Bose, T.K., Chahine, R., Merabet, M., and Thoen, J., J. de Phys. 45, 11329 (1984)Google Scholar
5. Bose, T.K., Campbell, B., Yagihara, S., and Thoen, J., Phys. Rev. A 36, 5767 (1987)Google Scholar
6. Buka, A. and Price, A. H., Mol. Cryst. Liq. Cryst. 116, 187 (1985).Google Scholar
7. Kreul, H. -G., Urban, S., and Würflinger, A., Phys. Rev. A 45, 8624 (1992).Google Scholar
8. Aliev, F. M. and Breganov, M. N., Sov. Phys. JETP. 68, 70 (1989).Google Scholar
9. Rozanski, S.R., Stanarius, R., Groothues, H., and , Kremer, Liq. Cryst. 20, 59 (1996).Google Scholar
10. Cramer, Ch., Cramer, Th., Arndt, M., Kremer, F., Naji, L. and Stannarius, R., Mol. Cryst. Liq. Cryst. 304, 209 (1997).Google Scholar
11. Sinha, G.P. and Aliev, F.M., Mol. Cryst. Liq. Cryst. 304, 309 (1997).Google Scholar
12. Cramer, Th. Cramer, Kremer, F., and Stannarius, R., J. Chem. Phys. 106, 3730 (1997).Google Scholar
13. Sinha, G.P. and Aliev, F.M., Phys. Rev. E 58, 2001 (1998).Google Scholar
14. Frunza, S., Frunza, L. and Schlonhals, A., J. Phys. IV France 10, Pr7–115 (2000).Google Scholar
15. Havriliak, S. and Negami, S., Polymer 8, 101 (1967).Google Scholar
16. Scaife, B. K. P., Principles of Dielectrics, (Clarendon Press, Oxford, 1989).Google Scholar
17. Disorder Effects on Relaxational Processes, edited by Richert, R. and Blumen, A., (Springler Verlag, Berlin 1994).Google Scholar
18. Maier, W. and Meier, G., Z. Naturforsch. 16a, 262 (1961).Google Scholar
19. Gennes, P.G. de and Prost, J., The Physics of Liquid Crystals, second ed., (Clarendon Press, Oxford 1993).Google Scholar
20. Thompson, P.A., Grest, G.S., and Robbins, M.O., Phys. Rev. Lett. 68, 3448 (1992).Google Scholar
21. Demirel, A.L. and Granik, S., Phys. Rev. Lett. 77, 2261 (1996).Google Scholar