Classification of Liquid Crystals According to Symmetry

Davis, Edward J.; Goodby, John W.

doi:10.1002/9783527671403.hlc003

Cited by 3 publications

(3 citation statements)

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“…A common classification scheme of LC phases is based on the specific anisometric shape of the constituent mesogenic molecules, although it should be emphasized that mesophase types should in principle be described and distinguished by their symmetry (which governs their physical properties) rather than by the shape of the individual components. 22 Conventional LCs often have a rod-like shape (calamitic mesogens) or a disk-like shape (discotic mesogens). In both cases, the molecules can be described as cylinders with a high degree of structural anisotropy.…”

Section: Liquid Crystals (Lcs): the "Fourth State Of Matter"mentioning

confidence: 99%

“…Many factors determine the type of mesophase formed by low molar mass thermotropic LCs, but molecular shape is an important parameter. A common classification scheme of LC phases is based on the specific anisometric shape of the constituent mesogenic molecules, although it should be emphasized that mesophase types should in principle be described and distinguished by their symmetry (which governs their physical properties) rather than by the shape of the individual components …”

Section: Classification Of Thermotropic Liquid Crystals and Their Mes...mentioning

confidence: 99%

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Ionic Liquid Crystals: Versatile Materials

et al. 2016

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This Review covers the recent developments (2005-2015) in the design, synthesis, characterization, and application of thermotropic ionic liquid crystals. It was designed to give a comprehensive overview of the "state-of-the-art" in the field. The discussion is focused on low molar mass and dendrimeric thermotropic ionic mesogens, as well as selected metal-containing compounds (metallomesogens), but some references to polymeric and/or lyotropic ionic liquid crystals and particularly to ionic liquids will also be provided. Although zwitterionic and mesoionic mesogens are also treated to some extent, emphasis will be directed toward liquid-crystalline materials consisting of organic cations and organic/inorganic anions that are not covalently bound but interact via electrostatic and other noncovalent interactions.

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Section: Liquid Crystals (Lcs): the "Fourth State Of Matter"mentioning

confidence: 99%

Section: Classification Of Thermotropic Liquid Crystals and Their Mes...mentioning

confidence: 99%

Ionic Liquid Crystals: Versatile Materials

et al. 2016

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“…Nevertheless, the nematic texture of the purified LC mixture has evolved, showing colored areas separated by black filaments known as Schlieren brushes [17]. These filaments correspond to an alignment of the LC molecules parallel to the axis of one or the other crossed polarizer, and, so, to an extinction position of the nematic state [28]. The non-purified sample retained the nematic marbled texture, with a large number of first-order inversion lines (thread-like texture), at low temperatures.…”

Section: Pom Analysismentioning

confidence: 99%

Chemical Characterization and Thermal Analysis of Recovered Liquid Crystals

et al. 2023

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Chemical, structural, and thermal properties of recovered nematic Liquid Crystal (LC) mixtures were investigated by applying several analytical techniques. A large quantity (65,700) of End-Of-Life (EOL) Liquid Crystal Display (LCD) screens were used to extract these LC blends. The studied EOL-LCD screens were heterogeneous in nature, particularly due to their different brands, production years, and dimensions. The collected TV and computer screens, as well as tablets, presented an average diagonal size of 24 inches. Chemical characterization revealed that the recovered compounds present typical chemical structures of LC molecules by the simultaneous presence of aliphatic chains and aromatic and polar groups. POM observations of these samples exhibited Schlieren and marble-like textures at room temperature, which are typical of nematic LCs. Moreover, thermal characterization and thermo-optical analysis showed that these LC mixtures displayed a broad nematic phase between −90 °C and +70 °C.

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