Special Issue "Advances in Liquid Crystals"

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A special issue of Crystals (ISSN 2073-4352).

Deadline for manuscript submissions: closed (30 June 2013)

Special Issue Editor

Guest Editor
Prof. Dr. Wolfgang Haase

Technische Universität Darmstadt, Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Petersenstrasse 20, D-64287 Darmstadt, Germany
Website | E-Mail
Fax: +49 6151 16 4924
Interests: liquid crystals; molecular magnetism; bioinorganic chemistry; nonlinear optics of functonal polymers

Special Issue Information

Dear Colleagues,

Liquid Crystals are one of the prominent Soft Materials, attractive for a broad and growing community of Scientists and Engineers.

Scientists based on their fundamental knowledge of Liquid Crystals trying to understand the working functions of Liquid Crystals in the biological environment, in Colloids, Polymers, LB-films etc. The applicability of Liquid Crystals in Optics, for Lasing, for functional Devices in a broad frequency range, is one of the key topics for applied scientists. Last but not least the technological verification of LCs in Displays is part of our daily life. Displays are an important media for transforming information, for entertainment etc. The current volume ‘Advances in Liquid Crystals’ provide a unique forum allowing the dissemination of results in the entire field of Liquid Crystals. Scientist and Engineers working in a broader sense on Liquid Crystals are invited to use this unique opportunity for presenting their work.

The topics summarized under the keywords should be considered only as examples, as guidelines. The volume is open for any advanced topics in the field of Liquid Crystals.

Prof. Dr. Wolfgang Haase
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 800 CHF (Swiss Francs).

Keywords

  • molecular design of liquid crystals
  • liquid crystals in biological systems
  • liquid crystalline nanocolloids
  • liquid crystals for photonics
  • liquid crystals for lasing
  • optical properties of liquid crystals
  • liquid crystals in the microwave and terahertz regime

Published Papers (7 papers)

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Research

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Open AccessArticle Influence of Mesogenic Properties of Cruciform-Shaped Liquid Crystals by Incorporating Side-Arms with a Laterally-Substituted-Fluorine
Crystals 2013, 3(2), 339-349; doi:10.3390/cryst3020339
Received: 23 March 2013 / Revised: 6 May 2013 / Accepted: 20 May 2013 / Published: 30 May 2013
Cited by 1 | PDF Full-text (582 KB) | HTML Full-text | XML Full-text
Abstract
Fluoro substitution in thermotropic liquid crystals provides a general way of modifying the properties of a parent system. Transition temperatures, mesophase types and other physical properties can be affected by fluoro substitution, so that frequently the behaviors of the parent compound can be
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Fluoro substitution in thermotropic liquid crystals provides a general way of modifying the properties of a parent system. Transition temperatures, mesophase types and other physical properties can be affected by fluoro substitution, so that frequently the behaviors of the parent compound can be manipulated and improved in a predictable manner. This paper discusses the effects of a fluoro substitution in each side-arm of 1,2,4,5-tetrakis((4-(alkoxy)phenyl)ethynyl)benzenes on the resulting mesomorphic properties characterized by optical polarizing microscopy and differential scanning calorimetry. Without any fluoro-substituted side-arms, longer chain-length leads to a wider nematic temperature range on cooling. Incorporation of a fluoro substitution in each side-arm induces the formation of a lamellar suprastructure, lowers transition temperatures and results in a wider mesophase temperature range on cooling. Full article
(This article belongs to the Special Issue Advances in Liquid Crystals)
Open AccessArticle Generation of Light Scattering States in Cholesteric Liquid Crystals by Optically Controlled Boundary Conditions
Crystals 2013, 3(1), 234-247; doi:10.3390/cryst3010234
Received: 18 February 2013 / Revised: 4 March 2013 / Accepted: 11 March 2013 / Published: 18 March 2013
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Abstract
Circularly polarized light was previously employed to stimulate the reversible and reconfigurable writing of scattering states in cholesteric liquid crystal (CLC) cells constructed with a photosensitive layer. Such dynamic photodriven responses have utility in remotely triggering changes in optical constructs responsive to optical
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Circularly polarized light was previously employed to stimulate the reversible and reconfigurable writing of scattering states in cholesteric liquid crystal (CLC) cells constructed with a photosensitive layer. Such dynamic photodriven responses have utility in remotely triggering changes in optical constructs responsive to optical stimulus and applications where complex spatial patterning is required. Writing of scattering regions required the handedness of incoming radiation to match the handedness of the CLC and the reflection bandwidth of the CLC to envelop the wavelength of the incoming radiation. In this paper, the mechanism of transforming the CLC into a light scattering state via the influence of light on the photosensitive alignment layer is detailed. Specifically, the effects of: (i) the polarization state of light on the photosensitive alignment layer; (ii) the exposure time; and (iii) the incidence angle of radiation on domain formation are reported. The photogenerated light-scattering domains are shown to be similar in appearance between crossed polarizers to a defect structure that occurs at a CLC/air interface (i.e., a free CLC surface). This observation provides strong indication that exposure of the photosensitive alignment layer to the circularly polarized light of appropriate wavelength and handedness generates an out-of-plane orientation leading to a periodic distortion of the original planar structure. Full article
(This article belongs to the Special Issue Advances in Liquid Crystals)
Figures

Review

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Open AccessReview High Birefringence Liquid Crystals
Crystals 2013, 3(3), 443-482; doi:10.3390/cryst3030443
Received: 28 June 2013 / Revised: 27 July 2013 / Accepted: 31 July 2013 / Published: 3 September 2013
Cited by 46 | PDF Full-text (1757 KB) | HTML Full-text | XML Full-text
Abstract
Liquid crystals, compounds and mixtures with positive dielectric anisotropies are reviewed. The mesogenic properties and physical chemical properties (viscosity, birefringence, refractive indices, dielectric anisotropy and elastic constants) of compounds being cyano, fluoro, isothiocyanato derivatives of biphenyl, terphenyl, quaterphenyl, tolane, phenyl tolane, phenyl ethynyl
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Liquid crystals, compounds and mixtures with positive dielectric anisotropies are reviewed. The mesogenic properties and physical chemical properties (viscosity, birefringence, refractive indices, dielectric anisotropy and elastic constants) of compounds being cyano, fluoro, isothiocyanato derivatives of biphenyl, terphenyl, quaterphenyl, tolane, phenyl tolane, phenyl ethynyl tolane, and biphenyl tolane are compared. The question of how to obtain liquid crystal with a broad range of nematic phases is discussed in detail. Influence of lateral substituent of different kinds of mesogenic and physicochemical properties is presented (demonstrated). Examples of mixtures with birefringence ∆n in the range of 0.2–0.5 are given. Full article
(This article belongs to the Special Issue Advances in Liquid Crystals)
Open AccessReview High Performance Negative Dielectric Anisotropy Liquid Crystals for Display Applications
Crystals 2013, 3(3), 483-503; doi:10.3390/cryst3030483
Received: 8 July 2013 / Revised: 21 August 2013 / Accepted: 26 August 2013 / Published: 3 September 2013
Cited by 20 | PDF Full-text (1241 KB) | HTML Full-text | XML Full-text
Abstract
We review recent progress in the development of high birefringence (Δn ≥ 0.12) negative dielectric anisotropy (Δε < 0) liquid crystals (LCs) for direct-view and projection displays. For mobile displays, our UCF-N2 (low viscosity, negative Δε, high Δn
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We review recent progress in the development of high birefringence (Δn ≥ 0.12) negative dielectric anisotropy (Δε < 0) liquid crystals (LCs) for direct-view and projection displays. For mobile displays, our UCF-N2 (low viscosity, negative Δε, high Δn) based homogeneous alignment fringe-field switching (called n-FFS) mode exhibits superior performance to p-FFS in transmittance, single gamma curve, cell gap insensitivity, and negligible flexoelectric effect. For projection displays using a vertical alignment liquid-crystal-on-silicon (VA LCOS), our high birefringence UCF-N3 mixture enables a submillisecond gray-to-gray response time, which is essential for color sequential displays without noticeable color breakup. Our low viscosity UCF-N2 also enables multi-domain VA displays to use a thinner cell gap for achieving faster response time. Full article
(This article belongs to the Special Issue Advances in Liquid Crystals)
Open AccessReview Soft Elasticity in Main Chain Liquid Crystal Elastomers
Crystals 2013, 3(2), 363-390; doi:10.3390/cryst3020363
Received: 6 February 2013 / Revised: 2 May 2013 / Accepted: 27 May 2013 / Published: 7 June 2013
Cited by 8 | PDF Full-text (4424 KB) | HTML Full-text | XML Full-text
Abstract
Main chain liquid crystal elastomers exhibit several interesting phenomena, such as three different regimes of elastic response, unconventional stress-strain relationship in one of these regimes, and the shape memory effect. Investigations are beginning to reveal relationships between their macroscopic behavior and the nature
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Main chain liquid crystal elastomers exhibit several interesting phenomena, such as three different regimes of elastic response, unconventional stress-strain relationship in one of these regimes, and the shape memory effect. Investigations are beginning to reveal relationships between their macroscopic behavior and the nature of domain structure, microscopic smectic phase structure, relaxation mechanism, and sample history. These aspects of liquid crystal elastomers are briefly reviewed followed by a summary of the results of recent elastic and high-resolution X-ray diffraction studies of the shape memory effect and the dynamics of the formation of the smectic-C chevron-like layer structure. A possible route to realizing auxetic effect at molecular level is also discussed. Full article
(This article belongs to the Special Issue Advances in Liquid Crystals)
Open AccessReview One-, Two-, and Three-Dimensional Hopping Dynamics
Crystals 2013, 3(2), 315-332; doi:10.3390/cryst3020315
Received: 10 January 2013 / Revised: 22 March 2013 / Accepted: 26 March 2013 / Published: 29 April 2013
Cited by 5 | PDF Full-text (29778 KB) | HTML Full-text | XML Full-text
Abstract
Hopping dynamics in glass has been known for quite a long time. In contrast, hopping dynamics in smectic-A (SmA) and hexatic smectic-B (HexB) liquid crystals (LC) has been observed only recently. The hopping in SmA phase occurs among the smectic layers (one-dimensionally), while
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Hopping dynamics in glass has been known for quite a long time. In contrast, hopping dynamics in smectic-A (SmA) and hexatic smectic-B (HexB) liquid crystals (LC) has been observed only recently. The hopping in SmA phase occurs among the smectic layers (one-dimensionally), while hopping in HexB phase occurs inside the layers (two-dimensionally). The hopping dynamics in SmA and HexB liquid crystal phases is investigated by parallel soft-core spherocylinders, while three-dimensional hopping dynamics in inherent glassy states is investigated by systems of Weeks–Chandler–Andersen (WCA) spheres. The temperature dependence of diffusion coefficients of hopping in SmA phase can be described by the Arrhenius equation characteristic of activation process. In HexB LC phase, the diffusion coefficients saturate at higher temperatures. In a system of WCA spheres, the values and temperature dependence of diffusion coefficients depend on the observed states. Full article
(This article belongs to the Special Issue Advances in Liquid Crystals)
Open AccessReview Photoaligning and Photopatterning — A New Challenge in Liquid Crystal Photonics
Crystals 2013, 3(1), 149-162; doi:10.3390/cryst3010149
Received: 22 January 2013 / Revised: 17 February 2013 / Accepted: 20 February 2013 / Published: 1 March 2013
Cited by 9 | PDF Full-text (1226 KB) | HTML Full-text | XML Full-text
Abstract Photoalignment possesses obvious advantages in comparison with the usually “rubbing” treatment of the substrates of liquid crystal display (LCD) cells. The application of the photoalignment and photopatterning nanotechnology for the new generation of photonic and display devices will be reviewed. Full article
(This article belongs to the Special Issue Advances in Liquid Crystals)

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