講者：Prof. 中戸晃之(Teruyuki Nakato)(日本九州工業大學) 演講題目：Nanosheet Liquid Crystals : Macroscopically Ordered Colloidal Structures Constructed by Inorganic Nanocrystals 演講時間：12/1~2 參看附件時間表 演講地點：台大生物技術研究中心1F演講 主持人：廖英志教授等 Abstract: Colloidal liquid crystals (LCs) of inorganic particles are very rare examples of inorganic soft structures.1 They are lyotropic systems that exhibit ordered structures of anisotropic particles like rods and plates at high particle concentrations. The LC phase is entropically driven based on the particles’ excluded volume effect. In the inorganic colloidal LCs, crystalline inorganic particles are mobile but ordered. Versatile properties of inorganic crystals such as semiconducting, dielectric, and (photo)catalytic functions, can be utilized in such materials. Colloidal LCs of inorganic nanosheets, called nanosheet LCs, are typical examples of such systems. They are constructed by extremely thin 2D particles obtained by exfoliation of inorganic layered crystals in solvents. The nanosheet LCs are characterized by mm-size mesogens with high anisotropy ensured by their thickness of around 1 nm. They are distinguished from conventional organic molecular LCs because of the mesogen size being much larger than that of molecules and the crystallinity of the mesogens. The size and robustness of the crystalline mesogens of the nanosheet LCs allow multiscale organization of hierarchical structures controlled over all length-scale from micro-, meso-, to macroscopic, which is impossible with the conventional organic LCs.2 The nanosheets have rich alternatives of arrangements for higher-order structures compared with 1D rods, because 2D particles have two different axes for regulation of their alignment. In fact, hierarchically structured arrays of nanosheet LCs are obtained with careful orientational control of the nanosheets. Two-stage manipulation of the LCs involving controlled LC domain growth and application of dual external forces generates the multiscale structures that are characterized by sub-mm to mm length scales (Figure 1). 
References: 1 N. Miyamoto, T. Nakato, Isr. J. Chem. 2012, 52, 881, and references therein. 2 T. Nakato, Y. Nono, E. Mouri, M. Nakata, Phys. Chem. Chem. Phys. 2014, 16, 955.