Optically Isotropic Liquid Crystal Mode Templated by Nanoporous Breath Figure Membrane

초록

In this study, a printing-based scalable method is proposed for the higher density of a liquid crystal (LC) nanodroplet structure suitable for the optically isotropic LC mode where the LC nanodomains are accurately templated by a nanoporous breath figure (BF) membrane. The highly porous BF polymeric template structure is reliably obtained by utilizing self-structured packing effects of the silica nanospheres achieved by doctor blade coating. A nanocomposite film with densely packed silica nanospheres encapsulated by the UV-crosslinked polymer matrix is made by controlling the blade coating velocity and blade gap conditions. This provides a higher LC fill-factor condition of the optically isotropic nanodroplet LC (OI-NDLC) mode with filling the LCs into the nanopores obtained after selective silica etching. The OI-NDLC structure templated by the nanoporous BF membrane made with the silica nanospheres of 300 nm can effectively resolve the scattering-induced optical loss and depolarization issues observable in the OI-NDLC mode prepared by conventional phase separation approaches due to the sufficiently reduced LC droplet size. The structure exhibits a much-improved light leakage level in the field-off optically isotropic state, a higher transmittance level as the field-induced Kerr operation, and resultant improved contrast ratio properties.

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