119th General Meeting of the KCS

Type Symposium
Area Smart Light-Guided Nanomaterials & Devices
Room No. 402호
Time FRI 15:30-:
Code MAT2-4
Subject Liquid crystal materials in the nanoconfinement and its optical applications
Authors 윤동기
KAIST 나노과학기술대학원, Korea
Abstract Liquid crystal (LC) material is now everyday substance on hand and the wall at home. This big success is based on the well-controlled LC domain in large area, now extending to the various kinds of applications beyond display applications, for example, organic semiconductors, optical devices and patterning applications. A key technique to realize these applications is the orientation control of LC phases over large areas with external efforts such as applying external electric or magnetic field, topographic confinement and mechanical shearing method.
Here, we used porous anodic aluminium oxide (AAO) film to control the nanometer-scaled structures of low molecular weight LC materials.[1-4] There have been many efforts to see the structural behaviours of LC phases in porous AAO film, including high-resolution calorimeter, deuteron nuclear magnetic resonance (2H-NMR) and dielectric relaxation spectroscopies. Although these techniques provide the information of the molecular dynamics for the orientation and the phase transition, they could not show the direct clues, indeed additional efforts should be used to analyse the data. However, grazing incidence X-ray diffraction (GIXD) technique can directly reveal the molecular ordering and orientation of LC phases in the nanoconfined geometry when this is used with a 2D CCD camera, directly showing the in-plane and out-of-plane information of the molecular behavior of LCs. We have controlled the molecular orientation of nematic (N) and smectic A (SmA) liquid crystal (LC) phase in chemically modified porous AAO film. The nano-templated LC could show the adjustable optical and photonic characteristics.[5,6]

References:
[1] H. Kim et al, Proc. Natl. Acad. Sci. U.S.A, 111, 14342 (2014)
[2] S. Lee, et al, Soft Matter, 11, 3653 (2015)
[3] S. Lee, et al, Langmuir, 31, 8156 (2015)
[4] H. Kim et al, Science Advances, 3, e1602102 (2017)
[5] S. H. Ryu et al, ACS. Appl. Mater. Interfaces, 9, 3186 (2017)
[6] S. H. Ryu et al, ACS Appl. Mater. Interfaces, 8, 17707 (2016)
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