http://www.mdpi.com/journal/ijms/special_issues/liquid-crystals/ 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 Materials Submission All papers should be submitted to ijms@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. The International Journal of Molecular Sciences is an international peer-reviewed monthly journal published by MDPI. Open Access publication fees are 800 CHF per paper. English correction fees and/or formatting fees (250 CHF) will be added in certain cases (1050 CHF per paper for those papers that require extensive additional formatting and/or English corrections). http://www.mdpi.com/1422-0067/11/3/943/ The stacking of discotic molecules (hexakis(alkoxy)diquinoxalino[2,3-a:2’,3’-c]phenazines) in the columnar phase sandwiched between two flat glass substrates has been studied. The surface free energy of the substrates, measured by means of sessile drop technique, is found to have significant influence on the way that the discotic molecules anchor on the surface, and a steady thermal state of the system is crucial for a homogenous orientation of the discotic columns. On a surface of high free energy, the discotic molecules anchor with their disc-face toward the surface. A decrease in the surface free energy of the substrate causes the discotic columns to tilt away from the normal of the substrate. http://www.mdpi.com/1422-0067/11/3/943/ Mon, 08 Mar 2010 00:00:00 CET International Journal of Molecular Sciences 2010-03-08 11 3 Article 943 955 1422-0067 Orientational Packing of a Confined Discotic Mesogen in the Columnar Phase 2010-03-08 doi: 10.3390/ijms11030943 Wenjun Zheng Ya-Ting Hu Cheng-Yan Chiang Chi Wi Ong http://www.mdpi.com/1422-0067/11/1/189/ Aqueous solutions of ethoxylated alcohols which form lyotropic liquid crystals at high concentrations (40–80%) were selected as model lubricating substances. Microscopic studies under polarized light and viscosity measurements were carried out in order to confirm the presence of liquid crystalline structures in the case of alcohol solutions with ethoxylation degrees of 3, 5, 7 and 10. Microscopic images and viscosity coefficient values characteristic of various mesophases were obtained. As expected, the viscosity of LLCs decreases considerably with an increase in shearing rate which is characteristic of liquid crystals being non-Newtonian liquids. Antiseizure properties were determined by means of a four-ball machine (T-02 Tester) and characterized by scuffing load (Pt), seizure load (Poz) and limiting pressure of seizure (poz). Alcohol ethoxylates forming mesophases in aqueous solutions have the strongest effect on the Pt values which are several times higher than those measured in the presence of water. Ethoxylates with higher degrees of ethoxylation exhibit higher values of scuffing load. Those changes have been interpreted as a result of higher cloud points at which those compounds lose their amphiphilic properties. In general, the presence of mesophases in the bulk phase and particularly in the surface phase may lead to the formation of a lubricant film which separates the frictionally cooperating elements of a friction pair. The antiseizure efficiency of alcohol solutions is highest up to the load value which does not exceed the scuffing load value. http://www.mdpi.com/1422-0067/11/1/189/ Tue, 12 Jan 2010 00:00:00 CET International Journal of Molecular Sciences 2010-01-12 11 1 Article 189 205 1422-0067 The Effect of Liquid Crystalline Structures on Antiseizure Properties of Aqueous Solutions of Ethoxylated Alcohols 2010-01-12 doi: 10.3390/ijms11010189 Marian Wlodzimierz Sulek Anna Bak http://www.mdpi.com/1422-0067/10/11/5031/ Polyimides having dendritic side chains were investigated. The terphenylene diamine monomer having a first-generation monodendron, 3,4,5-tris(n-dodecyloxy)-benzoate and the monomer having a second-generation monodendron, 3,4,5-tris[-3’,4’,5’-tri(n-dodecyloxy)benzyloxy]benzoate were successfully synthesized and the corresponding soluble dendritic polyimides were obtained by polycondensation with conventional tetracarboxylic dianhydride monomers such as benzophenone tertracarboxylic dianhydride (BTDA). The two-step polymerizations in NMP that is a general method for the synthesis of soluble polyimides is difficult; however, the expected dendritic polyimides can be obtained in aromatic polar solvents such as m-cresol and pyridine. The solubility of these dendoronized polyimides is characteristic; soluble in common organic solvents such as dichloromethane, chloroform, toluene and THF. These dendronized polyimides exhibited high glass transition temperatures and good thermal stability in both air and under nitrogen. Their application as alignment layers for LCDs was investigated, and it was found that these polyimides having dendritic side chains were applicable for the vertically aligned nematic liquid crystal displays (VAN-LCDs). http://www.mdpi.com/1422-0067/10/11/5031/ Thu, 19 Nov 2009 00:00:00 CET International Journal of Molecular Sciences 2009-11-19 10 11 Article 5031 5053 1422-0067 Dendronized Polyimides Bearing Long-Chain Alkyl Groups and Their Application for Vertically Aligned Nematic Liquid Crystal Displays 2009-11-19 doi: 10.3390/ijms10115031 Yusuke Tsuda Jae Min OH Renpei Kuwahara http://www.mdpi.com/1422-0067/10/11/4772/ Several divinylic mesogenic monomers were synthesized based on coupling the monomer 4-(4-pentenyloxy)benzoic acid with chlorohydroquinone, 2,5-dihydroxyacetophenone, methylhydroquinone or 2-methoxyhydroquinone. This resulted in novel mesogens of phenylene esters with different lateral substituent groups. The effect of the lateral substituent group on the thermotropic phase behavior for these liquid crystalline compounds was investigated using DSC and optical polarized microscopy. All the mesogens proved to have a wide nematic liquid crystalline range. Only the phenylene ester, which has a methoxy lateral substituent, exhibited both nematic and smectic phases. Structural confirmation of all new derivatives was accomplished by 1H- and 13C-NMR spectroscopic analysis, along with CH elemental analysis. http://www.mdpi.com/1422-0067/10/11/4772/ Wed, 04 Nov 2009 00:00:00 CET International Journal of Molecular Sciences 2009-11-04 10 11 Article 4772 4788 1422-0067 Synthesis, Characterization and Texture Observations of Calamitic Liquid Crystalline Compounds 2009-11-04 doi: 10.3390/ijms10114772 Maher A. Qaddoura Kevin D. Belfield http://www.mdpi.com/1422-0067/10/11/4754/ Home-based soft X-ray time-resolved scattering experiments with nanosecond time resolution (10 ns) and nanometer spatial resolution were carried out at a table top soft X-ray plasma source (2.2–5.2 nm). The investigated system was the lyotropic liquid crystal C16E7/paraffin/glycerol/formamide/IR 5. Usually, major changes in physical, chemical, and/or optical properties of the sample occur as a result of structural changes and shrinking morphology. Here, these effects occur as a consequence of the energy absorption in the sample upon optical laser excitation in the IR regime. The liquid crystal shows changes in the structural response within few hundred nanoseconds showing a time decay of 182 ns. A decrease of the Bragg peak diffracted intensity of 30% and a coherent macroscopic movement of the Bragg reflection are found as a response to the optical pump. The Bragg reflection movement is established to be isotropic and diffusion controlled (1 μs). Structural processes are analyzed in the Patterson analysis framework of the time-varying diffraction peaks revealing that the inter-lamellar distance increases by 2.7 Å resulting in an elongation of the coherently expanding lamella crystallite. The present studies emphasize the possibility of applying TR-SXRD techniques for studying the mechanical dynamics of nanosystems. http://www.mdpi.com/1422-0067/10/11/4754/ Wed, 04 Nov 2009 00:00:00 CET International Journal of Molecular Sciences 2009-11-04 10 11 Article 4754 4771 1422-0067 Time-Resolved Soft X-ray Diffraction Reveals Transient Structural Distortions of Ternary Liquid Crystals 2009-11-04 doi: 10.3390/ijms10114754 Wilson Quevedo Christian Peth Gerhard Busse Mirko Scholz Klaus Mann Simone Techert http://www.mdpi.com/1422-0067/10/10/4559/ The Δ- and Λ-isomerism of octahedral metal complexes is employed as a source of chirality for inducing chiral nematic phases. By applying a wide range of chiral metal complexes as a dopant, it has been found that tris(β-diketonato)metal(III) complexes exhibit an extremely high value of helical twisting power. The mechanism of induction of the chiral nematic phase is postulated on the basis of a surface chirality model. The strategy for designing an efficient dopant is described, together with the results using a number of examples of Co(III), Cr(III) and Ru(III) complexes with C2 symmetry. The development of photo-responsive dopants to achieve the photo-induced structural change of liquid crystal by use of photo-isomerization of chiral metal complexes is also described. http://www.mdpi.com/1422-0067/10/10/4559/ Fri, 23 Oct 2009 00:00:00 CEST International Journal of Molecular Sciences 2009-10-23 10 10 Review 4559 4574 1422-0067 Application of Δ- and Λ-Isomerism of Octahedral Metal Complexes for Inducing Chiral Nematic Phases 2009-10-23 doi: 10.3390/ijms10104559 Hisako Sato Akihiko Yamagishi http://www.mdpi.com/1422-0067/10/10/4498/ Defect inspection plays a critical role in thin film transistor liquid crystal display (TFT-LCD) manufacture, and has received much attention in the field of automatic optical inspection (AOI). Previously, most focus was put on the problems of macro-scale Mura-defect detection in cell process, but it has recently been found that the defects which substantially influence the yield rate of LCD panels are actually those in the TFT array process, which is the first process in TFT-LCD manufacturing. Defect inspection in TFT array process is therefore considered a difficult task. This paper presents a novel inspection scheme based on kernel principal component analysis (KPCA) algorithm, which is a nonlinear version of the well-known PCA algorithm. The inspection scheme can not only detect the defects from the images captured from the surface of LCD panels, but also recognize the types of the detected defects automatically. Results, based on real images provided by a LCD manufacturer in Taiwan, indicate that the KPCA-based defect inspection scheme is able to achieve a defect detection rate of over 99% and a high defect classification rate of over 96% when the imbalanced support vector machine (ISVM) with 2-norm soft margin is employed as the classifier. More importantly, the inspection time is less than 1 s per input image. http://www.mdpi.com/1422-0067/10/10/4498/ Thu, 22 Oct 2009 00:00:00 CEST International Journal of Molecular Sciences 2009-10-22 10 10 Article 4498 4514 1422-0067 In-TFT-Array-Process Micro Defect Inspection Using Nonlinear Principal Component Analysis 2009-10-22 doi: 10.3390/ijms10104498 Yi-Hung Liu Chi-Kai Wang Yung Ting Wei-Zhi Lin Zhi-Hao Kang Ching-Shun Chen Jih-Shang Hwang http://www.mdpi.com/1422-0067/10/9/4102/ Two decades ago, the literature dealing with the possible applications of low molar mass liquid crystals, also called monomer liquid crystals (MLCs), only included about 50 references. Today, thousands of papers, conference reports, books or book chapters and patents refer to the study and applications of MLCs as lubricants and lubricant additives and efforts are made to develop new commercial applications. The development of more efficient lubricants is of paramount technological and economic relevance as it is estimated that half the energy consumption is dissipated as friction. MLCs have shown their ability to form ordered boundary layers with good load-carrying capacity and to lower the friction coefficients, wear rates and contact temperature of sliding surfaces, thus contributing to increase the components service life and to save energy. This review includes the use of MLCs in lubrication, and dispersions of MLCs in conventional polymers (PDMLCs). Finally, new lubricating system composed of MLC blends with surfactants, ionic liquids or nanophases are considered. http://www.mdpi.com/1422-0067/10/9/4102/ Fri, 18 Sep 2009 00:00:00 CEST International Journal of Molecular Sciences 2009-09-18 10 9 Review 4102 4115 1422-0067 Liquid Crystals in Tribology 2009-09-18 doi: 10.3390/ijms10094102 Francisco-José Carrión Ginés Martínez-Nicolás Patricia Iglesias José Sanes María-Dolores Bermúdez http://www.mdpi.com/1422-0067/10/9/4009/ Quantitative understanding of the mechanical behavior of biological liquid crystals such as proteins is essential for gaining insight into their biological functions, since some proteins perform notable mechanical functions. Recently, single-molecule experiments have allowed not only the quantitative characterization of the mechanical behavior of proteins such as protein unfolding mechanics, but also the exploration of the free energy landscape for protein folding. In this work, we have reviewed the current state-of-art in single-molecule bioassays that enable quantitative studies on protein unfolding mechanics and/or various molecular interactions. Specifically, single-molecule pulling experiments based on atomic force microscopy (AFM) have been overviewed. In addition, the computational simulations on single-molecule pulling experiments have been reviewed. We have also reviewed the AFM cantilever-based bioassay that provides insight into various molecular interactions. Our review highlights the AFM-based single-molecule bioassay for quantitative characterization of biological liquid crystals such as proteins. http://www.mdpi.com/1422-0067/10/9/4009/ Thu, 10 Sep 2009 00:00:00 CEST International Journal of Molecular Sciences 2009-09-10 10 9 Review 4009 4032 1422-0067 Experimental and Computational Characterization of Biological Liquid Crystals: A Review of Single-Molecule Bioassays 2009-09-10 doi: 10.3390/ijms10094009 Kilho Eom Jaemoon Yang Jinsung Park Gwonchan Yoon Young Soo Sohn Shinsuk Park Dae Sung Yoon Sungsoo Na Taeyun Kwon http://www.mdpi.com/1422-0067/10/9/3971/ We review the theoretical research on the influence of disorder on structure and phase behavior of condensed matter system exhibiting continuous symmetry breaking focusing on liquid crystal phase transitions. We discuss the main properties of liquid crystals as adequate systems in which several open questions with respect to the impact of disorder on universal phase and structural behavior could be explored. Main advantages of liquid crystalline materials and different experimental realizations of random field-type disorder imposed on liquid crystal phases are described. http://www.mdpi.com/1422-0067/10/9/3971/ Thu, 10 Sep 2009 00:00:00 CEST International Journal of Molecular Sciences 2009-09-10 10 9 Review 3971 4008 1422-0067 The Influence of Disorder on Thermotropic Nematic Liquid Crystals Phase Behavior 2009-09-10 doi: 10.3390/ijms10093971 Vlad Popa-Nita Ivan Gerlič Samo Kralj