http://www.mdpi.com/journal/materials/special_issues/liquid-crystals-materials/ Dear Colleagues, Since the first reported observation of a liquid crystalline behavior by the Austrian botanist Friedrich Reinitzer in 1888, liquid crystals have attracted immense scientific interest. Scientists have been drawn to the study of liquid crystals by both their unusual mesomorphic properties, being intermediate between the solid, crystalline state and the isotropic liquid phase, and the relative aesthetics attained upon observing the often spectacular mesophases between cross polarizers on an optical microscope. Over the past three to four decades, a number of unique properties exhibited by liquid crystalline materials in response to external stimuli have been exploited in a number of important technologies. For example, ferroelectric liquid crystals have been key components in the digital age, leading a revolution in display technology. Thermotropic liquid crystalline materials continue to find their place in numerous products including the healthcare field. Lyotropic liquid crystalline polymers have propelled the field of high strength, light weight materials for a number of military and civilian applications, including their important contribution in body armor. It is fitting that we have special issues in the Journal of Molecular Sciences and Materials dedicated to this still very intriguing class of materials that promises to continue to be an integral part of emerging technologies. Kevin D. Belfield, Ph.D. Guest Editor Related Special Issue Liquid Crystals in the International Journal of Molecular Sciences Submission All papers should be submitted to materials@mdpi.com. To be published continuously until the deadline and papers will be listed together at the special issue website. Submitted papers should not have been published previously, nor be under consideration for publication elsewhere. All papers are refereed through a peer-review process. A guide for authors is available on the Instructions for Authors page. Materials is an international peer-reviewed quarterly journal published by MDPI. Review manuscripts: Before writing their manuscripts, potential authors of review articles should forward the title and a short abstract to materials@mdpi.com. We will then provide feedback on the suitability of the topic. Article Processing Charges (APC) Article Processing Charges (APC) will be waived for well prepared manuscripts of invited papers. For the first two volumes of this new journal the APC are of 300 CHF (or 550 CHF per paper for those papers that require extensive additional formatting and/or English corrections). http://www.mdpi.com/1996-1944/5/1/156/ We found an error in the Scheme 1 in our paper published in Materials [1]. [...] http://www.mdpi.com/1996-1944/5/1/156/ Mon, 09 Jan 2012 00:00:00 CET Materials 2012-01-09 5 1 Correction 156 156 1996-1944 Correction: Goto, H. et al. Liquid Crystalline π-Conjugated Copolymers Bearing a Pyrimidine Type Mesogenic Group. Materials 2009, 2, 22-37 2012-01-09 doi: 10.3390/ma5010156 Kohsuke Kawabata Hiromasa Goto http://www.mdpi.com/1996-1944/3/2/827/ The liquid crystalline dimer of 4-(4-pentenyloxy)benzoic acid, a member of the n-alkoxybenzoic acid homologous series, was synthesized using potassium carbonate supported on alumina as catalyst. The acid dimer complex exhibited three mesophases; identified as nematic, smectic X1 and smectic X2. Phase transition temperatures and the corresponding enthalpies were recorded using differential scanning calorimetry upon both heating and cooling. The mesophases were identified by detailed texture observations by variable temperature polarized light microscopy. The nematic phase was distinguished by a fluid Schlieren texture and defect points (four and two brushes) while the smectic phases were distinguished by rigid marble and mosaic textures, respectively. http://www.mdpi.com/1996-1944/3/2/827/ Fri, 29 Jan 2010 00:00:00 CET Materials 2010-01-29 3 2 Article 827 840 1996-1944 Probing the Texture of the Calamitic Liquid Crystalline Dimer of 4-(4-Pentenyloxy)benzoic Acid 2010-01-29 doi: 10.3390/ma3020827 Maher A. Qaddoura Kevin D. Belfield http://www.mdpi.com/1996-1944/2/4/1955/ This paper focuses on the fabrication via simple melt blending of thermotropic liquid crystal polyester (TLCP) nanocomposites reinforced with a very small quantity of modified carbon nanotube (CNT) and the unique effects of the modified CNT on the physical properties of the nanocomposites. The thermal, mechanical, and rheological properties of modified CNT-reinforced TLCP nanocomposites are highly dependent on the uniform dispersion of CNT and the interactions between the CNT and TLCP, which can be enhanced by chemical modification of the CNT, providing a design guide of CNTreinforced TLCP nanocomposites with great potential for industrial uses. http://www.mdpi.com/1996-1944/2/4/1955/ Thu, 26 Nov 2009 00:00:00 CET Materials 2009-11-26 2 4 Review 1955 1974 1996-1944 Carbon Nanotube-Reinforced Thermotropic Liquid Crystal Polymer Nanocomposites 2009-11-26 doi: 10.3390/ma2041955 Jun Young Kim http://www.mdpi.com/1996-1944/2/4/1734/ Inorganic layered crystals exemplified by clay minerals can be exfoliated in solvents to form colloidal dispersions of extremely thin inorganic layers that are called nanosheets. The obtained “nanosheet colloids” form lyotropic liquid crystals because of the highly anisotropic shape of the nanosheets. This system is a rare example of liquid crystals consisting of inorganic crystalline mesogens. Nanosheet colloids of photocatalytically active semiconducting oxides can exhibit unusual photoresponses that are not observed for organic liquid crystals. This review summarizes experimental work on the phase behavior of the nanosheet colloids as well as photochemical reactions observed in the clay and semiconducting nanosheets system. http://www.mdpi.com/1996-1944/2/4/1734/ Thu, 29 Oct 2009 00:00:00 CET Materials 2009-10-29 2 4 Review 1734 1761 1996-1944 Liquid Crystalline Behavior and Related Properties of Colloidal Systems of Inorganic Oxide Nanosheets 2009-10-29 doi: 10.3390/ma2041734 Teruyuki Nakato Nobuyoshi Miyamoto http://www.mdpi.com/1996-1944/2/4/1662/ We demonstrate a polarizer-free electro-optical switch using dye-doped liquid crystal (LC) gels. The mechanism of dye-doped LC gels mainly involves the combination of polymer scattering and dye absorption. However, the domain size of polymer networks, dye concentration, LC concentration, and fabrication process can all affect the phase separation process and thus result in dye-doped LC gels with different electro-optical performance. We have studied experimentally the factors which can affect the dye-doped LC gels. The potential applications for dye-doped LC gels are flexible displays and electrically tunable light shutters. http://www.mdpi.com/1996-1944/2/4/1662/ Mon, 26 Oct 2009 00:00:00 CET Materials 2009-10-26 2 4 Article 1662 1673 1996-1944 A Polarizer-Free Electro-Optical Switch Using Dye-Doped Liquid Crystal Gels 2009-10-26 doi: 10.3390/ma2041662 Yi-Hsin Lin Hung-Chun Lin Jhih-Ming Yang http://www.mdpi.com/1996-1944/2/4/1636/ The relationships between molecular structures and properties of anthraquinone dichroic dyes were studied and dyes with large solubilities and dichroic ratios were developed. The yellow anthraquinone dye behaves as a quencher of the coumarin dye, and the mixture has a large absorption coefficient without fluorescence. These technologies can enlarge the color reproduction area of three-layer guest-host liquid crystal displays (GHLCDs) 1.6-fold. The performances of the prototype reflective three-layer GH-LCDs are as follows: the white state luminous reflectance is 43% and the contrast is 5.3, indicating that they are promising candidates for portable information systems with full-color images. http://www.mdpi.com/1996-1944/2/4/1636/ Fri, 23 Oct 2009 00:00:00 CEST Materials 2009-10-23 2 4 Review 1636 1661 1996-1944 Development of Highly Soluble Anthraquinone Dichroic Dyes and Their Application to Three-Layer Guest-Host Liquid Crystal Displays 2009-10-23 doi: 10.3390/ma2041636 Hiroki Iwanaga http://www.mdpi.com/1996-1944/2/3/1305/ Photo-induced phase transitions are characterized by the transformation from phase A to phase B through the absorption of photons. We have investigated the mechanism of the photo-induced phase transitions of four different ternary systems CiE4/alkane (i) with n = 8, 10, 12, 14; cyclohexane/H2O. We were interested in understanding the effect of chain length increase on the dynamics of transformation from the microemulsion phase to the liquid crystal phase. Applying light pump (pulse)/x-ray probe (pulse) techniques, we could demonstrate that entropy and diffusion control are the driving forces for the kind of phase transition investigated. http://www.mdpi.com/1996-1944/2/3/1305/ Thu, 17 Sep 2009 00:00:00 CEST Materials 2009-09-17 2 3 Article 1305 1322 1996-1944 Photo-Induced Phase Transitions to Liquid Crystal Phases: Influence of the Chain Length from C8E4 to C14E4 2009-09-17 doi: 10.3390/ma2031305 Marcel Petri Gerhard Busse Wilson Quevedo Simone Techert http://www.mdpi.com/1996-1944/2/2/674/ The interaction between an external action and the order parameter, via a dependence described by a so-called Lifshitz invariant, is very important to determine the final configuration of liquid crystal cells. The external action can be an electric field applied to the bulk or the confinement due to free surfaces or cell walls. The Lifshitz invariant includes the order parameter in the form of an elastic strain. This coupling between elastic strains and fields, inserted in a Landau-Ginzburg formalism, is well known and gives rise to striction effects causing undulations in the director configuration. We want to discuss here the role of Lifshitz coupling terms, following an approach similar to that introduced by Dzyaloshinskii for magnetic materials. Case studies on nematics in planar and cylindrical cells are also proposed. http://www.mdpi.com/1996-1944/2/2/674/ Tue, 16 Jun 2009 00:00:00 CEST Materials 2009-06-16 2 2 Article 674 698 1996-1944 Role of Lifshitz Invariants in Liquid Crystals 2009-06-16 doi: 10.3390/ma2020674 Amelia Sparavigna http://www.mdpi.com/1996-1944/2/2/636/ This article reviews the current status of self-assembling liquid crystalline polymers comprising cholesterol. This article will focus on synthesis, structure-property relationships and strategies to direct ordering and packing of meso- and nanostructures of cholesterol polymers in the neat- or melt state and in solution. The applications of these self-assembled structures will be presented. http://www.mdpi.com/1996-1944/2/2/636/ Tue, 02 Jun 2009 00:00:00 CEST Materials 2009-06-02 2 2 Review 636 660 1996-1944 Polymers Comprising Cholesterol: Synthesis, Self-Assembly, and Applications 2009-06-02 doi: 10.3390/ma2020636 Yuxiang Zhou Victoria A. Briand Nitin Sharma Suk-kyun Ahn Rajeswari M. Kasi http://www.mdpi.com/1996-1944/2/2/549/ Active and dynamic modulation of light has been one of major contributions of liquid crystals to Optics. The spectrum of application range from signposting panels to high resolution imaging. The development of new materials is the key to continued progress in this field. To promote this we will present in this paper recent uses of liquid crystals as active or adaptive modulators of light. Besides, we will reflect on their current limitations. We expect with this to contribute to the progress in the field of liquid crystals and thus the development of new useful tools for Active and Adaptive Optics. http://www.mdpi.com/1996-1944/2/2/549/ Tue, 12 May 2009 00:00:00 CEST Materials 2009-05-12 2 2 Review 549 561 1996-1944 Impact of Liquid Crystals in Active and Adaptive Optics 2009-05-12 doi: 10.3390/ma2020549 Justo Arines http://www.mdpi.com/1996-1944/2/2/499/ We investigate two different textures of smectic A liquid crystals. These textures are particularly symmetric when they are observed at crossed polars optical microscopy. For both textures, a model has been made in order to examine the link between the defective macroscopic texture and the microscopic disposition of the layers. We present in particular in the case of some hexagonal tiling of circles (similar to the Apollonius tiling) some numeric simulation in order to visualize the smectic layers. We discuss of the nature of the smectic layers, which permit to assure their continuity from one focal conic domain to another adjacent one. http://www.mdpi.com/1996-1944/2/2/499/ Wed, 22 Apr 2009 00:00:00 CEST Materials 2009-04-22 2 2 Article 499 513 1996-1944 Focal Conic Stacking in Smectic A Liquid Crystals: Smectic Flower and Apollonius Tiling 2009-04-22 doi: 10.3390/ma2020499 Claire Meyer Loic Le Cunff Malika Belloul Guillaume Foyart http://www.mdpi.com/1996-1944/2/1/95/ This review focuses on recent developments in the chemistry of side chain liquid crystal polymers. It concentrates on current trends in synthetic methods and novel, well defined structures, supramolecular arrangements, properties, and applications. The review covers literature published in this century, apart from some areas, such as dendritic and elastomeric systems, which have been recently reviewed. http://www.mdpi.com/1996-1944/2/1/95/ Wed, 11 Mar 2009 00:00:00 CET Materials 2009-03-11 2 1 Review 95 128 1996-1944 Side-chain Liquid Crystal Polymers (SCLCP): Methods and Materials. An Overview 2009-03-11 doi: 10.3390/ma2010095 Tomasz Ganicz Włodzimierz Stańczyk http://www.mdpi.com/1996-1944/2/1/38/ Seven symmetrical azomethines with two imine groups (HC=N) were synthesized by condensation of the benzene-1,4-dicarboxaldehydewith five amines (first group: A1-A5) and of the 2,5-thiophenedicarboxaldehyde with two amines (second group: AT1-AT2). Additionally, two unsymmetrical azomethines were obtained by a two step condensation of benzene-1,4-dicarboxaldehydewith pyren-1-amine(1st step) (abbreviated hereinafter as AP1) and then AP1 was reacted with4-dodecylaniline or 4-hexadecylaniline (2nd step) (third group: AP1A-AP1B). Liquid crystalline properties of the azomethines were studied by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and UV-vis spectroscopy in the function of temperature [UV-vis(T)]. The Wide-Angle X-ray Diffraction (WAXD) technique was used to probe the structural properties of the azomethines. Mesomorphic behavior was observed for symmetrical and unsymmetrical azomethines, obtained from the benzene-1,4-dicarboxaldehyde and symmetrical ones prepared from 2,5-thiophenedicarboxaldehyde and different amineshaving aliphatic chains. Based on the POM and DSC measurements the following mesophases were detected: nematic, smectic A, smectic C, smectic F (I), smectic G (J). http://www.mdpi.com/1996-1944/2/1/38/ Fri, 06 Feb 2009 00:00:00 CET Materials 2009-02-06 2 1 Article 38 61 1996-1944 Mesomorphic Behavior of Symmetrical and Unsymmetrical Azomethines with Two Imine Groups 2009-02-06 doi: 10.3390/ma2010038 Agnieszka Iwan Henryk Janeczek Bozena Jarzabek Patrice Rannou http://www.mdpi.com/1996-1944/2/1/22/ Phenylene-thiophene-based liquid crystalline π-conjugated copolymers bearing mesogenic groups as side chains were synthesized via a Stille polycondensation reaction and confirmed to exhibit a nematic liquid crystal phase at appropriate temperatures. The formation of a nematic phase, but not a smectic phase indicates cooperation of the main chain and side chain in the formation of a nematic main-chain/side-chain liquid crystal phase. The generation of polarons in the main chain as charge carriers during in-situ vapor doping of iodine is confirmed to increase with a doping progresses, exhibiting Dysonian paramagnetic behavior typical of conductive polymers. http://www.mdpi.com/1996-1944/2/1/22/ Fri, 16 Jan 2009 00:00:00 CET Materials 2009-01-16 2 1 Article 22 37 1996-1944 Liquid Crystalline π-Conjugated Copolymers Bearing a Pyrimidine Type Mesogenic Group 2009-01-16 doi: 10.3390/ma2010022 Kohsuke Kawabata Hiromasa Goto