title: Discontinuous thermal diffusivity change due to the anchoring transition of a liquid crystal on a perfluoropolymer surface.
abstract: Thermal diffusivity of a liquid crystal, 4'-butyl-4-heptyl-bicyclohexyl-4-carbonitrile, was measured using a temperature wave method. The liquid crystal was sandwiched by two glass substrates, which were treated with three different surface agents for providing distinct molecular orientations. Here, we demonstrate that: 1) a large thermal diffusivity anisotropy arising from different orientations, that is, planar and homeotropic states, was found in the nematic and smectic A phases; 2) when substrates were coated with a perfluoropolymer, abrupt changes of the thermal diffusivity were observed in the nematic phase both on cooling and heating due to the discontinuous anchoring transition between planar and homeotropic states. The temperature dependence of the thermal diffusivity anisotropy was well described by a power law, with an exponent of 0.27 according to the mean-field theory.
authors.affiliation: Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro-ku, Tokyo 152-8550 (Japan), Fax: (+81) 3-5734-2497.
authors.forename: Michiru
authors.initials: M
authors.lastname: Uehara
authors.forename: Satoshi
authors.initials: S
authors.lastname: Aya
authors.forename: Fumito
authors.initials: F
authors.lastname: Araoka
authors.forename: Ken
authors.initials: K
authors.lastname: Ishikawa
authors.forename: Hideo
authors.initials: H
authors.lastname: Takezoe
authors.forename: Junko
authors.initials: J
authors.lastname: Morikawa
keywords: anchoring transitions; anisotropy; liquid crystals; phase transitions; thermal diffusivity