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Lyotropic Chromonic Liquid Crystals in Aligned Films for Applications as Polarizing Coatings
Schneider, Tod,Golovin, Andrii,Lee, Jong-Chan,Lavrentovich, Oleg D. The Korean Infomation Display Society 2004 Journal of information display Vol.5 No.2
We describe dried oriented films with anisotropic structural and optical properties prepared from the aqueous solutions of plank-like molecules, the so-called Lyotropic Chromonic Liquid Crystals (LCLCs). The dried LCLC films may be used as optical elements, such as polarizers, compensators, color filters, or retardation plates in the UV, visible, or infrared parts of spectrums. The optical quality of the films is determined by the uniformity of the molecular alignment, which often distorted by periodic variations of the director field. We describe different ways to improve the alignment properties of the films by using additives. We present compositions capable of polarizing effects in visible and UV parts of spectrum.
Internal structure visualization and lithographic use of periodic toroidal holes in liquid crystals
Yoon, Dong Ki,Choi, M. C.,Kim, Yun Ho,Kim, Mahn Won,Lavrentovich, Oleg D.,Jung, Hee-Tae Nature Publishing Group 2007 NATURE MATERIALS Vol.6 No.11
The formation of a large-area ordered structure by organic molecular soft building blocks is one of the most exciting interdisciplinary research areas in current materials science and nanotechnology. So far, several distinct organic building blocks—including colloids, block copolymers and surfactants—have been examined as potential materials for the creation of lithographic templates. Here, we report that perfect ordered arrays of toric focal conic domains (TFCDs) covering large areas can be formed by semi-fluorinated smectic liquid crystals. Combined with controlled geometry, that is, a microchannel, our smectic liquid-crystal system exhibits a high density of TFCDs that are arranged with remarkably high regularity. Direct visualization of the internal structure of the TFCDs clearly verified that the smectic layers were aligned normal to the side walls and parallel to the top surface, and merge with the circular profile on the bottom wall surface. Moreover, we demonstrate a new concept: smectic liquid-crystal lithography. Grown in microchannels from a mixture of liquid-crystal molecules and fluorescent particles, TFCDs of the smectic liquid crystals acted as a template, trapping particles in an ordered array. Our findings pose new theoretical challenges and potentially enable lithographic applications based on smectic liquid-crystalline materials.
Kim, Yun Ho,Yoon, Dong Ki,Jeong, Hyeon Su,Lavrentovich, Oleg D.,Jung, Hee‐,Tae WILEY‐VCH Verlag 2011 Advanced functional materials Vol.21 No.4
<P><B>Abstract</B></P><P>Recently, it has been reported that liquid crystal (LC) defects can be used to create highly periodic templates by controlling the surface anchoring and the elastic properties of LC molecules. The self‐assembled defect ordering of the LC materials takes advantage of the ability to achieve fast stabilization of molecular ordering and structure due to the reversible and non‐covalent interactions of the LC molecules. In this Featre Article, the defect structures of liquid crystalline materials will be demonstrated by the surface anchoring and elastic properties. A particular focus are the focal conic domains (FCDs) that are commonly observed in SmA liquid crystals and their lamellar lyotropic counterparts, which form periodic defect ordered structures. In addition, methodologies for creating lithographic templates from the defect order will be described. Finally, the review closes with a discussion of toric focal conic domain arrays that have been fabricated in this manner and used for various applications.</P>