Dielectric measurements of liquid crystals confined to molecular sieves

The molecular dynamics of the liquid crystals 8CB and 5CB confined to the m esopores of the molecular sieve Al-MCM-41 with pore diameter less than 2.5 nm was investigated by broadband dielectric spectroscopy. The phase transit ions 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 melti ng temperature of the bulk material a relaxation process occurs for molecul es confined to the mesoporous material which does not exist in the bulk liq uid crystal state. The temperature dependence of the relaxation rate of tha t process obeys a Vogel-Fulcher-Tammann law.