Hostname: page-component-77c89778f8-9q27g Total loading time: 0 Render date: 2024-07-24T10:19:54.832Z Has data issue: false hasContentIssue false
  • English
  • Français

The Influence of Boundary Conditions and Surface Layer Thickness on Dielectric Relaxation of Liquid Crystals Confined in Cylindrical Pores

Published online by Cambridge University Press:  21 March 2011

Z. Nazario ,
G. P. Sinha  and
F.M. Aliev
Z. Nazario
Affiliation:
Dept. of Physics, University of Puerto Rico, San Juan, PR 00931, USA
G. P. Sinha
Affiliation:
Dept. of Physics, Case Western Reserve University, Cleveland, OH 44106, USA
F.M. Aliev
Affiliation:
Dept. of Physics, University of Puerto Rico, San Juan, PR 00931, USA Yokoyama Nano-structured Liquid Crystal Project, TRC, Tsukuba, Ibaraki, 300-2635, Japan
Get access

Abstract

Dielectric spectroscopy was applied to investigate the dynamic properties of liquid crystal octylcyanobiphenyl (8CB) confined in 2000 Å cylindrical pores of Anopore membranes with homeotropic and axial (planar) boundary conditions on the pore walls. Homeotropic boundary conditions allow the investigation of the librational mode in 8CB by dielectric spectroscopy. We found that the dynamics of the librational mode is totally different from the behavior observed in investigations of relaxation due to reorientation of molecules around their short axis. The interpretation of the temperature dependence of relaxation times and of the dielectric strength of the librational mode needs the involvement of the temperature dependence of orientational order parameter. For samples with axial boundary conditions, layers of LCs with different thickness were obtained on the pore walls as a result of controlled impregnation of porous matrices with 8CB from solutions of different liquid crystal concentration. The process due to rotation of molecules around their short axis with single relaxation time observed for bulk 8CB is replaced by a process with a distribution of relaxation times in thin layers. This relaxation process broadens with decreasing layer thickness.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 651: Symposium T – Dynamics in Small Confining Systems V , 2000 , T7.22.1
Copyright
Copyright © Materials Research Society 2001

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. Rozanski, S.R., Stanarius, R., Groothues, H., and Kremer, F., Liq. Cryst. 20, 59 (1996).Google Scholar
9. Sinha, G.P. and Aliev, F.M., Phys. Rev. E 58, 2001 (1998).Google Scholar
10. Zalar, B., Zumer, S., and Finotello, D., Phys. Rev. Let. 84, 4866 (2000).Google Scholar
11. Havriliak, S. and Negami, S., Polymer 8, 101 (1967).Google Scholar
12. Maier, W. and Meier, G., Z. Naturforsch. 16a, 262 (1961).Google Scholar
13. Gennes, P.G. de and Prost, J., The Physics of Liquid Crystals, second ed., (Clarendon Press, Oxford 1993).Google Scholar
14. Thompson, P.A., Grest, G.S., and Robbins, M.O., PRL, 68, 3448 (1992).Google Scholar
15. Demirel, A.L. and Granik, S., Phys. Rev. Lett., 77, 2261 (1996).Google Scholar