TY - JOUR A1 - Calus, S. A1 - Kityk, A.V. A1 - Borowik, L. A1 - Lefort, R. A1 - Morineau, D. A1 - Krause, Christina A1 - Schönhals, Andreas A1 - Busch, M. A1 - Huber, P. T1 - High-resolution dielectric study reveals pore-size-dependent orientational order of a discotic liquid crystal confined in tubular nanopores JF - Physical review E N2 - We report a high-resolution dielectric study on a pyrene-based discotic liquid crystal (DLC) in the bulk state and confined in parallel tubular nanopores of monolithic silica and alumina membranes. The positive dielectric anisotropy of the DLC molecule at low frequencies (in the quasistatic case) allows us to explore the thermotropic collective orientational order. A face-on arrangement of the molecular discs on the pore walls and a corresponding radial arrangement of the molecules is found. In contrast to the bulk, the isotropic-to-columnar transition of the confined DLC is continuous, shifts with decreasing pore diameter to lower temperatures, and exhibits a pronounced hysteresis between cooling and heating. These findings corroborate conclusions from previous neutron and x-ray-scattering experiments as well as optical birefringence measurements. Our study also indicates that the relative simple dielectric technique presented here is a quite efficient method in order to study the thermotropic orientational order of DLC-based nanocomposites. PY - 2015 DO - https://doi.org/10.1103/PhysRevE.92.012503 SN - 1539-3755 SN - 1063-651X VL - 92 IS - 1 SP - 012503-1 EP - 012503-6 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-33813 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -