Study of nematic liquid crystals confined in molecular sieves. 4-Octyl-4 '-cyanobipbenyl (8CB) in AlMCM-41 and cloverite

The confinement of a nematic liquid crystal (LC), 4-octyl-4'-cyanobiphenyl, in the molecular sieves of AIMCM-41 and cloverite type is investigated by dielectric spectroscopy, thermal analysis and FTIR spectroscopy. We focus h erein on the samples containing the LC not only in the pores and cavities, but also on the external surface of the molecular sieve grains. A bulk-like dynamical behaviour was found for these samples. An interaction of the LC molecules with the surface took place by coordination to Lewis sites and by hydrogen bonding with OH groups. (C) 2001 Elsevier Science B.V. All rights reserved.