Model Systems for Liquid Crystal Based Dispersed Heterogeneous Materials

Porous matrices with determined pore size, volume fraction and structure can be used as model systems to understand physical properties of dispersed liquid crystals (LC) - material important for different applications. Using photon correlation spectroscopy and dielectric spectroscopy we investigated dynamic properties of nematic liquid crystal dispersed in porous matrices with randomly oriented, interconnected pores (porous glasses with average pore sizes of 100 A and 1000 A) and parallel cylindrical pores (Anopore membranes with pore diameters of 200 A and 2000 A). Since the structural characteristics of these matrices are nearly independent of the temperature, all observable effects due to temperature changes can be attributed to the change in the physical properties of the second component (bC). The spatial confinement and a highly developed interface in porous matrices have a strong influence on the optical and dielectric properties of confined LC which is resulted in: appearance of at least two new dielectrically active modes, absent in the bulk and existence of slow glass-like relaxational process detected in both dielectric and photon correlation experiments.