Finite size and interfacial effects in liquid crystals confined to random porous matrices: Broadband dielectric spectroscopy investigations

The dielectric behavior of confined 8CB has been investigated by means of ultra broad-band dielectric spectroscopy. New features such as two relaxation processes with characteristic frequencies around (1-10) Hz and 100 kHz, which are absent in bulk liquid crystals, were observed in confined geometries. These processes arise due to the relaxation of interfacial polarization at pore wall-liquid crystal interface and the hindered rotation of the molecules near the interface respectively. Two other bulk like modes due to the rotation of polar molecules around their short axis and due to tumbling of molecules were also observed in confined geometries. We also investigated these processes in the supercooled state. All observed processes are non Debye like.