43. Nonequilibrium dynamics of liquid crystal films with chiral order(poster presentation,Soft Matter as Structured Materials)

この論文は国立情報学研究所の電子図書館事業により電子化されました。カイラリティーをもった液晶分子によって構成された単分子膜は、分子の長軸が膜の法線に対して一様に傾いた2次元的な液晶相を形成し得る。この液晶膜を一方向に通過する水蒸気流束が存在するとき、膜面内の分子配向が集団的な回転運動をすることが実験的に観察されている。我々は、この現象に対する簡単なモデルを構成し、それに基づいた数値シミュレーションを行うことにより、熱平衡状態ではカイラル秩序が現れないようなパラメータ領域において、水蒸気流束が存在する非平衡系においては、それが動的な秩序として現れ得ることを示す

A thermomechanical coupling in cholesteric liquid crystals: Unidirectional rotation of double-twist cylinders driven by heat flux

We made aggregates of cholesteric liquid crystalline Cylinders with Double-Twist orientational structure (DTC) and investigated their rigid-body rotation under a temperature gradient, focusing on how the rotational speed should depend on the cylinder size. The experimental results showed that the angular velocity of the DTC aggregates linearly increased with the height of the cylinders and was inversely proportional to the base area. With a phenomenological equation, we analyzed the torque caused by the heat flux and its balance with the viscous friction, and found that the simple analysis well explained the size-dependence of the rotation of the DTC aggregates. The coupling constant between the heat flux and the torque to drive the rigid-body rotation was in the same order of magnitude as that for the director rotation

Formation of Concentric Silica Nanogrooves Guided by the Curved Surface of Silica Particles

The flexible control of nanopatterns by a bottom-up process at the nanometer scale is essential for nanofabrication with a finer pitch. We have previously reported that for the fabrication of linear nanopatterns with sub-5 nm periodicity on Si substrates the outermost surfaces of assembled micelles facing the substrates can be replicated with soluble silicate species generated from the Si substrates under basic conditions. In this study, concentrically arranged nanogrooves with a sub-5 nm periodicity were prepared on Si substrates by replicating the outermost surfaces of bent micelles guided by silica particles. The Si substrates, where silica particles and surfactants films were deposited, were exposed to an NH₃–water vapor mixture. During the vapor treatment, cylindrical micelles became arranged in concentric patterns centered on the silica particles, and their outermost surfaces facing the substrates were replicated by soluble silicate species on the Si substrates. The thinness of the surfactant film on the substrate is crucial for the formation of concentric silica nanogrooves because the out-of-plane orientations of the micelles are suppressed at the interface. Surprisingly, the domains of the concentric silica nanogrooves spread to much larger areas than the maximum cross-sectional areas of the particles, and the size of the domains increased linearly with the radii of the particles. The extension of concentric nanogrooves is discussed on the basis of the orientational elastic energies of the micelles around one silica particle. This study of the formation of bent nanogrooves guided by the outlines of readily deposited nanoscale objects provides a new nanostructure-guiding process