Special Issue "Liquid Crystals 2011"

Guest Editor
Prof. Dr. W. Haase
Darmstadt University of Technology, Eduard-Zintl-Institut für, Anorganische und Physikalische Chemie, Petersenstr. 20, 64287 Darmstadt, Germany
Website: http://www1.tu-darmstadt.de/fb/ch/Fachgebiete/PC/kondmat/start_en.html
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Dear Colleagues,

A Liquid Crystal can be considered as a truly multifunctional material being a thermotropic or lyotropic anisotropic fluid. Applications for Liquid Crystal Displays, for Photonics, for a broad range of Devices and Switchers, even for Analytical Tools or their functionalities in Life Science etc. are based essential on such anisotropic properties. The field of anisotropic properties is very rich, the physics of such anisotropic fluids is a hot topic, their design and chemical realization is still a challenge.
Basically most of the Liquid Crystals consist of All-Organic Compounds, but their existence is not restricted on those. By introducing closed or open shell metals as constitutive element the very interesting field of Metallomesogens opens a lot of pronounced and new properties.
Functionalized Nanomaterials doped in Liquid Crystals as for instance Au, BaTiO₃, SWCNTs or MWCNTs lead to Nanocolloids with enhanced or quite new properties allowing nanostructuring.
Contributions to topics addressed above but not necessary limited are desirable.

Prof. Dr. W. Haase
Guest Editor

Related Special Issues in other Journals

Liquid Crystals 2011 in Materials

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Type of Paper: Article
Title: Langmuir-Blodgett Technique as a Tool for Homeotropic Alignment of Fluorinated Liquid Crystals Mixed with Arachidic Acid
Authors: Anna Modlińska and Danuta Bauman
Affiliation: Faculty of Technical Physics, Poznan University of Technology, 60-965 Poznan, Poland; E-Mail: danuta.bauman@put.poznan.pl (D.B)
Abstract: Liquid crystal displays (LCDs) are still the most dominant displays, which are widely used commercially. However, to stay on the market and be competitive with other types of displays their parameters must be continually improved by using new effects and novel liquid crystal materials with pre-designed appropriate physical properties. In the last decade, fluorinated liquid crystals have attracted much attention of researchers. It turned out that the replacement of one or more hydrogen atoms by fluorine atoms in the molecular structure leads to liquid crystalline compounds characterized by a specific, unique properties. The biggest advantages of this type of compounds are very stable, relatively broad mesophase range, low viscosity, low conductivity and low threshold voltage. Therefore, these materials are suitable for use as components of commercial mixtures. Mesogenic molecules in which fluorine atoms are substituted in the lateral position are particularly interesting. Such substitution may indeed lead to obtain liquid crystalline compounds with negative dielectric anisotropy. The demand for this type of liquid crystals grew at the time of development and use of liquid crystal displays working in vertical alignment (VA) technology. In comparison to the most popular TN LCDs, VA-type displays are characterized by a much wider, symmetrical viewing angle, enhanced picture quality and contrast, less visible pixel structure. They are also easier  to control by the electric field, which is due to low anchoring energy. VA-type displays require preliminary homeotropic orientation of molecules. There are several techniques to obtain such an arrangement, most of them require the use of a suitable surfactant. However, not always manage to get molecules alignment of a good quality. An alternative way to obtain initial homeotropic orientation of  liquid crystal molecules is to use technique based on deposition on a solid substrate a Langmuir-Blodgett (LB) film from an appropriate fatty acid, acting as a layer inducing orientation ("command layer").
In the paper we described the behaviour of the mixtures of some fluoro-substituted liquid crystals with arachidic acid in monolayers formed at air-water (Langmuir films) and air-solid substrate (Langmuir-Blodgett films) interfaces. We have shown that using Langmuir-Blodgett technique it is possible to obtain uniform homeotropic alignment of fluorinated mesogenic molecules.