J. Phys. IV France 10 (2000) Pr7-115-Pr7-118
Dielectric measurements of liquid crystals confined to molecular sievesS. Frunza1, L. Frunza1 and A. Schönhals2
1 National Institute of Material Physics, P.O. Box Mg 07, 76900 Bucharest-Magurele, Romania
2 Federal Institute of Material Research and Testing, Unter den Eichen 87, 12205 Berlin, Germany
The molecular dynamics of the liquid crystals 8CB and 5CB confined to the mesopores of the molecular sieve Al-MCM-41 with pore diameter less than 2.5 nm was investigated by broadband dielectric spectroscopy. The phase transitions of the liquid crystal cannot be detected for the molecules confined to the pores. Moreover it has been found that even about 20 K below the melting temperature of the bulk material a relaxation process occurs for molecules confined to the mesoporous material which does not exist in the bulk liquid crystal state. The temperature dependence of the relaxation rate of that process obeys a Vogel-Fulcher-Tammann law.
© EDP Sciences 2000