Uehara Michiru, Aya Satoshi, Araoka Fumito, Ishikawa Ken, Takezoe Hideo, Morikawa Junko
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.
Chemphyschem. 2014 May 19;15(7):1452-6. doi: 10.1002/cphc.201300975. Epub 2014 Feb 13.
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.
采用温度波法测量了液晶4'-丁基-4-庚基-双环己基-4-腈的热扩散率。该液晶夹在两个玻璃基板之间，这两个玻璃基板用三种不同的表面活性剂处理，以提供不同的分子取向。在此，我们证明：1）在向列相和近晶A相中发现了由不同取向（即平面态和垂直取向态）引起的大的热扩散率各向异性；2）当基板涂覆全氟聚合物时，由于平面态和垂直取向态之间的不连续锚定转变，在向列相冷却和加热时均观察到热扩散率的突然变化。热扩散率各向异性的温度依赖性可用幂律很好地描述，根据平均场理论，指数为0.27。
