title: Continuous paranematic-to-nematic ordering transitions of liquid crystals in tubular silica nanochannels.
abstract: The optical birefringence of rodlike nematogens (7CB, 8CB), imbibed in parallel silica channels with 10 nm diameter and 300 microm length, is measured and compared to the thermotropic bulk behavior. The orientational order of the confined liquid crystals, quantified by the uniaxial nematic ordering parameter, evolves continuously between paranematic and nematic states, in contrast to the discontinuous isotropic-to-nematic bulk phase transitions. A Landau-de Gennes model reveals that the strength of the orientational ordering fields, imposed by the silica walls, is beyond a critical threshold, that separates discontinuous from continuous paranematic-to-nematic behavior. Quenched disorder effects, attributable to wall irregularities, leave the transition temperatures affected only marginally, despite the strong ordering fields in the channels.
authors.affiliation: Institute for Computer Science, Czestochowa University of Technology, Aleja Armii Krajowej 17, P-42200 Czestochowa, Poland. andriy.kityk@univie.ac.at
authors.forename: Andriy V
authors.initials: AV
authors.lastname: Kityk
authors.forename: Matthias
authors.initials: M
authors.lastname: Wolff
authors.forename: Klaus
authors.initials: K
authors.lastname: Knorr
authors.forename: Denis
authors.initials: D
authors.lastname: Morineau
authors.forename: Ronan
authors.initials: R
authors.lastname: Lefort
authors.forename: Patrick
authors.initials: P
authors.lastname: Huber