Direct observation of liquid crystal phases under nanoconfinement: A grazing incidence X-ray diffraction study

ABSTRACT

We have controlled the molecular orientation of nematic and smectic A liquid crystal (LC) phases in a porous anodic aluminium oxide (AAO) film, in which the pore diameter was varied from 20 nm to 100 nm. Surface anchoring to induce planar and homeotropic molecular arrangement was controlled by chemical modification of the AAO inner surface. Direct observation of the molecular orientation of LC phases was performed using grazing incidence X-ray diffraction technique, showing in-plane and out-of-plane molecular orientation, and the corresponding layer orientation. The systematic investigation of LC phases under nanoconfinement will be useful to design various kinds of physicochemical environments to control the orientation of other soft matters.

GRAPHICAL ABSTRACT

KEYWORDS:

• Liquid crystal phases
• orientation control
• surface treatment
• confined geometries

Acknowledgements

The authors thank Professor Sang Bok Lee for useful discussion. The experiments at the PLS-II were supported in part by MSIP and POSTECH.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

This work was supported by a grant from the National Research Foundation of Korea (NRF) [Grant Numbers 2014K1A3A1A21001342 and 2014M3C1A3052537].