Effect of Confinement on the Structural, Dielectric, and Dynamic Properties of Liquid Crystals in Anopores

Based on data from broadband dielectric spectroscopy (BDS) and a molecular model based on the Landau–de Gennes concept, the effect of confinement on the structural, dielectric, and dynamic properties of 4-n-pentyl-4′-cyanobiphenyl (5CB) in the nematic phase is studied. The dielectric permittivity and relaxation times were previously obtained by the BDS technique in a wide frequency range (1MHz≤f≤1GHz) in the nematic phase composed of 5CB molecules confined to Anopore membranes with pore sizes of 0.2 μm. The distance-dependent values of the order parameter P2(r), the relaxation time τ(r)≡τ001(r), the rotational diffusion coefficient D⊥(r), and both rotational viscosity coefficients γi(r) (i=1,2) as functions of the distance r away from the bounding surface are calculated by a combination of existing statistical-mechanical approaches and data obtained by the BDS technique. Reasonable agreement between the calculated and experimental values of γi(i=1,2) for bulk 5CB is obtained.