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Showing papers in "Molecular Crystals and Liquid Crystals in 2017"


Journal ArticleDOI
TL;DR: A review of mathematical contributions, ideas and questions concerning liquid crystals can be found in this paper, where a review is given of some mathematical contributions and ideas, ideas, and questions about liquid crystals.
Abstract: A review is given of some mathematical contributions, ideas and questions concerning liquid crystals.

71 citations


Journal ArticleDOI
Hideo Takezoe1
TL;DR: A brief overview of polar liquid crystals (LCs) is given in this paper with a tutorial manner, which includes chiral smectic C ferroelectric LCs (FLCs), chiral columnar FLCs, chiral and nonchiral ferronematic LCs, various bent-shaped polar LCs such as B1, B2, B4, B5, B6, B7, twist-bend nematic, orthogonal polar smectics, and non-chiral columnars.
Abstract: Brief overview of polar liquid crystals (LCs) is given with a tutorial manner They are chiral smectic C ferroelectric LCs (FLCs), chiral smectic CA antiferroelectric LCs (AFLCs), their ferrielectric subphase LCs, chiral columnar FLCs, chiral and nonchiral ferronematic LCs, various bent-shaped polar LCs such as B1, B2, B4, B7, twist-bend nematic, orthogonal polar smectic, and nonchiral columnar FLCs After summarizing the definition of FLCs and AFLCs, and techniques to certify these polar LCs, their polar structures and characteristics are described together with important review articles

29 citations


Journal ArticleDOI
TL;DR: In this article, the UV spectral characterization of a smectic-C liquid crystal 4,4′-bis(n-alkoxy)azoxybenzene (n = 14) (C40H66N2O3) has been carried out.
Abstract: In the present article, UV spectral characterization of a smectic-C liquid crystal 4,4′-bis(n-alkoxy)azoxybenzene (n = 14) (C40H66N2O3) has been carried out. Structure of the molecule has b...

27 citations


Journal ArticleDOI
TL;DR: In this article, a comparative study of non-fluorinated and centrally fluorinated 1,4-bis(phenylethynyl)benzene molecules with the same tail length of heptyl, hexyloxy, and hexylthio groups at both para positions was performed.
Abstract: In order to figure out the effects of terminal groups on phase transitions and birefringence, we performed a comparative study for non-fluorinated and centrally fluorinated liquid crystalline 1,4-bis(phenylethynyl)benzene molecules with the same tail length of heptyl, hexyloxy, hexylthio groups at both para positions These molecules showed remarkable effects of the terminal groups to the phase transitions The birefringence values at close temperatures, as well as an order parameter (S) = 1 for a fluorinated family, are in the following order of alkylthio > alkoxy > alkyl analogues, corresponding to their polarizabilities

27 citations


Journal ArticleDOI
Jae-Won Huh1, Byeong-Hun Yu1, Joon Heo1, Seong-Min Ji1, Tae-Hoon Yoon1 
TL;DR: In this paper, the authors introduce technologies for liquid crystal (LC) light shutters that can scatter and absorb the incident light simultaneously, which is preferable for display applications, and compare the performance of these technologies.
Abstract: By switching a light shutter placed at the backside of a see-through display, we can select the transparent or high-visibility mode of the display panel. In this paper, we introduce technologies for liquid crystal (LC) light shutters that can scatter and absorb the incident light simultaneously, which is preferable for display applications. A light shutter for display applications can be realized in the normally-opaque mode by using a double-layered structure using cholesteric LCs or a single-layered structure using dye-doped cholesteric LCs. Whereas, it can be realized in the normally-transparent mode by using dye-doped polymer-networked LC cells using negative or positive LCs. Operation of each of the technologies is reviewed and the performance of these technologies is compared in this paper.

23 citations


Journal ArticleDOI
TL;DR: In this article, a perovskite solar cell was constructed using gel polymer electrolyte as the charge transport medium, which has a power conversion efficiency of 1.28% with open circuit voltage (Voc) 0.58 mV, short circuit current density (Jsc) 3.74 mV and fill factor (FF) 59.18%.
Abstract: This study deals with the characterization of methylammonium lead iodide (MAPbI3) material and the fabrication of perovskite solar cells using gel polymer electrolyte as the charge transport medium. The crystalline lead–based perovskite has been verified by x-ray diffraction (XRD). The [100], [200], [210], [211], [220], [300] and [222] reflection planes can be observed at 2? angles of 14.10°, 28.35°, 31.90°, 34.95°, 40.40°, 43.15° and 50.20°, indicating a cubic crystal symmetry for CH3NH3PbI3. EDX spectrum showed a Pb:I ratio of approximately 1:3 as in CH3NH3PbI3. The band gap for lead-based perovskite is 1.45 eV estimated from UV-Vis absorption spectroscopy. The nanocrystalline MAPbI3 have been observed using field emission scanning electron microscopy (FESEM), where the average cuboid size of perovskite nanocrystals is 380 nm. The cell have been fabricated using gel polymer electrolyte with composition 17.02 wt.% PVA–13.93 wt.% TBAI–0.96 wt.% I2– 68.09 wt.% DMF. The cell exhibits a power conversion efficiency (PCE) of 1.28% with open circuit voltage (Voc) 0.58 mV, short circuit current density (Jsc) 3.74 mA cm?2 and fill factor (FF) 59.18%.

23 citations


Journal ArticleDOI
TL;DR: The development of the twisted nematic liquid crystal display (TN-LCD) by Schadt and Helfrich in 1970 started the development of field effect LCDs as discussed by the authors.
Abstract: The invention of the twisted nematic liquid crystal display (TN-LCD) by Schadt and Helfrich in 1970 started the development of field-effect LCDs.Today, LCDs are the dominant flat panel display technology. Milestones in the ongoing research and development are sub-millisecond responding nematic liquid crystal (LC) materials, integration of silicon-driving electronics into display substrates, complex optical thin-films enabling excellent image quality and, last but not least, high resolution, contact-free photo-alignment/pattering of monomeric liquid crystals in displays and surface-aligned liquid crystal polymer (LCP) optical films. Photo-alignment of liquid crystal molecules by the linear photo-polymerization (LPP) technology enables high resolution, fast responding multi-domain LCDs with broad fields of view and complex, ultra-thin liquid crystal polymer retarder films. LCD-applications range from reflective displays for digital watches with virtually zero power consumption to large-area flat tel...

22 citations


Journal ArticleDOI
TL;DR: In this article, the title compound was isolated and investigated by experimental X-ray diffraction method and density functional theory (DFT) calculational properties and spectroscopic methodologies.
Abstract: The title compound was isolated and investigated by experimental X-ray diffraction method and density functional theory (DFT) calculational properties and spectroscopic methodologies. The experimen...

20 citations


Journal ArticleDOI
TL;DR: In this article, a solvent casting method using pectin and ionic liquid (IL) was used to synthesize polymer electrolytes (PEs), potentially interesting for solid-state electrochemical devices applications.
Abstract: New polymer electrolytes (PEs), potentially interesting for solid-state electrochemical devices applications, were synthesized by a solvent casting method using pectin and ionic liquid (IL) N,N,N-trimethyl-N-(2-hydroxyethyl)ammonium bis(trifluoromethylsulfonyl)imide ([N1 1 1 2(OH)] [NTf2]. The resulting electrolytes besides being moderately homogenous and thermally stable below 155°C, they also exhibited good mechanical properties. The SPE membranes were analyzed by differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and complex impedance spectroscopy.

19 citations


Journal ArticleDOI
TL;DR: Triphenylamine is a propeller-like structural chromophore with a nitrogen atom center as mentioned in this paper, which has a large steric hindrance and hyper conjugation electronic effect, which can enhance the stability of the nitrogen atomic radical.
Abstract: Triphenylamine is a propeller-like structural chromophore with a nitrogen atom center. The compound has a large steric hindrance and hyper conjugation electronic effect, which can enhance the stability of the nitrogen atomic radical. Triphenylamine materials also have a high hole mobility due to their unique free radicals nature. In this review, we started with the methods of the synthesis including traditional Ullmann, Suzuki Coupling, Heck, Wittig, Stille, and Sonogashira Reaction synthesis, and also the basic experimental and theoretical methods for the characterization of triphenylamine materials. Then, we discussed the properties of triphenylamine, including the optoelectronics, electroluminescence, and electrochromism. Finally, we reviewed the recent progress in the main applications of triphenylamine materials in the field of organic optoelectronic solar cells, electroluminescence materials, and electrochromic materials. In conclusion, this review of triphenylamine materials is a valuable r...

19 citations


Journal ArticleDOI
TL;DR: In this paper, a study of in vitro biodegradation of poly(3-hydroxybutyrate) (PHB) in model conditions was performed, where porcine pancreatic lipase solutions at different concentrations in the two buffer systems (phosphate-buffered saline (PBS) and simulating body fluid (SBF)) were chosen as model biodegrading media.
Abstract: A study of in vitro biodegradation of poly(3-hydroxybutyrate) (PHB) in model conditions was performed. The porcine pancreatic lipase solutions at different concentrations in the two buffer systems (phosphate-buffered saline (PBS) and simulating body fluid (SBF)) were chosen as model biodegradation media. At first, optimal concentration of pancreatic lipase (0.25 mg/ml in PBS) was determined: in these media the decomposition of PHB films realized faster according to the data of gravimetric analysis. Differential scanning calorimetry showed an increase in the crystallinity of the samples (from 49% to 59%) after enzymatic degradation. These data are confirmed by method of nanoindentation, where the increase of the Young's modulus during the degradation (from 1.37 GPa to 4.4 GPa) was shown. This is due to the crystallization of the amorphous polymer component, and its decomposition and dissolving. During biodegradation three types of polymer ultrastructure changes were observed on the surfaces of the ...

Journal ArticleDOI
TL;DR: In this paper, a method to generate optical vortices via reflection from cholesteric liquid crystals with planar alignment is presented, which is operable at multiple wavelengths with theoretically high conversion efficiency (lossless) without requiring fine control of retardation.
Abstract: Singular optics is an emerging field, in which an optical wave with a helical wavefront is handled for optical manipulation and nanofabrication. We present a method to generate optical vortices via reflection from cholesteric liquid crystals with planar alignment. Numerical and experimental results show that the device is operable at multiple wavelengths with theoretically high conversion efficiency (lossless) without requiring fine-control of retardation. Although the operational wavelength range is limited by the birefringence and helix pitch of the material, broadband operation is possible by expanding the reflection band width by either introducing a pitch distribution or stacking multiple devices.

Journal ArticleDOI
TL;DR: In this article, the structural and optical characterization of pure polymer dispersed liquid crystal and doped PDLC with inorganic nanoparticles like CuO, ZnO and Zn
Abstract: Our research paper discusses the structural and optical characterization of pure Polymer Dispersed Liquid Crystal and doped PDLC with inorganic nanoparticles like CuO, ZnO and Zn. PDLC is prepared ...

Journal ArticleDOI
TL;DR: The influence of the terminal side chain and lateral nitro on mesomorphism due to the flexibility and polarity of lateral group is investigated in this article, where a new homologues series is synthesized to accomplish the task.
Abstract: The influence of the terminal side chain and lateral nitro on mesomorphism due to the flexibility and polarity of lateral group is investigated. A new homologues series is synthesized to accomplish...

Journal ArticleDOI
TL;DR: In this paper, a simple model of Ionic Liquid Crystals represented by mixtures of positively charged ellipsoidal Gay-Berne particles and negatively charged spherical Lennard-Jones particles is presented.
Abstract: We use a simple model of Ionic Liquid Crystals represented by mixtures of positively charged ellipsoidal Gay-Berne particles and negatively charged spherical Lennard-Jones particles. This system wi...

Journal ArticleDOI
TL;DR: In this paper, a series of chalconyl derivatives consisting of two phenyl rings bonded through a central bridge was synthesized to study the effect of molecular structure on liquid crystal properties in general and with a focus on molecular rigidity.
Abstract: ABSTRACT Novel liquid crystal materials (LCs) of low temperature range (53°C to 75°C) have been synthesized through a series of chalconyl derivatives consisting of two phenyl rings bonded through a –CH˭CH‒CO‒ central bridge to study the effect of molecular structure on LC properties in general and with a focus on molecular rigidity. The novel homologues series (C1 to C18) consists of thirteen homologues with general formula RO‒C6H4‒CH˭CH‒CO‒C6H4‒OC10H21(n) (meta). The C1, C2, C3 homologues are nonliquid crystals (NLC) and the rest of the homologues (C4 to C18) are either monotropic or enantiotropic liquid crystals. C4 to C6 homologues are enantiotropicnematic and the rest of the mesomorphic homologues are (C7 to C18) monotropicsmectic in addition to monotropicnematic character. Transition and melting temperatures including textures of homologues were determined by an optical polarizing (POM) microscopy equipped with a heating stage. Textures of a nematic phase are threaded or Schlieren, and that of the smectic phase are of the type Smectic A or C as judged directly from the heating top of the microscope. Thermal stability for smectic is very poor and of the nematic is (N-I) 69.3°C whose, total mesophase length ranges between 07.0 to 14.0°C at C8 and C4 homologues respectively.

Journal ArticleDOI
TL;DR: The mesomorphic properties of linear chalconyl ester homologous series can be tuned in a predictable fashion with tail groups (OC5H11) substituents on the terminal side and nitro group substitute on the outer side.
Abstract: The mesomorphic properties of linear chalconyl ester homologous series can be tuned in a predictable fashion with tail groups (‒OC5H11) substituents on the terminal side and nitro group substitute ...

Journal ArticleDOI
TL;DR: The mesomorphic properties of linear schiff base-chalconyl ester homologous series can be designed in a predictable fashion with using various alcohol and para-tert-butyl phenol as discussed by the authors.
Abstract: GRAPHICAL ABSTRACT ABSTRACT The mesomorphic properties of linear schiff base-chalconyl ester homologous series can be designed in a predictable fashion with using various alcohol and para-tert-butyl phenol. We have synthesized total 14 novel liquid crystalline compounds and divided into two parts, i.e, series-1 (D1 to D10) and series-2 (E1 to E4). The result of both the series are compared and discussed. These compounds possess a rod-like geometry with rigid linear spacers and possessing smectic C and smectic A phases, while nematogenic phase was achieved by increasing the flexibility and broadening of tail-ended group in molecule. The texture image of mesophases is needle; rod like; broken fan type and nematic texture images are the type of schlieren and threaded in some homologue. All these compounds were characterized by elemental analyses and spectroscopic techniques such as FTIR and 1H and 13C [NMR] spectroscopies. The mesomorphic properties of these compounds were observed by optical polarized light microscopy and differential scanning calorimetry.

Journal ArticleDOI
TL;DR: Two coordination polymers, {Ln(2stp)(4,4′-bipy)(H2O)] and [Ln = Dy (1) and Eu (2), have been characterized by solid state UV-vis as mentioned in this paper.
Abstract: Two coordination polymers, {[Ln(2-stp)(4,4′-bipy)(H2O)].(H2O)}, [Ln = Dy (1) and Eu (2), 2-stp = 2-sulfoterephthalate and 4,4′-bipy = 4,4′-bipyridine] have been characterized by solid state UV-vis,...

Journal ArticleDOI
TL;DR: In this article, the main source of aromatic compounds in nature, lignin possesses heterogeneous composition which has high potential to be used in many industrial purposes, and has been used as retarda...
Abstract: Known as the main source of aromatic compounds in nature, lignin possesses heterogeneous composition which has high potential to be used in many industrial purposes. Lignin has been used as retarda...

Journal ArticleDOI
TL;DR: A series of hydrophobic symmetrical azines: 1,2-bis[4-(n-alkoxy)benzylidene]hydrazine (where, nalkoxy: O(CH2)nH, n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16, or 18) have been prepared following an efficient and practical method as mentioned in this paper.
Abstract: A series of hydrophobic symmetrical azines: 1,2-bis[4-(n-alkoxy)benzylidene]hydrazine (where, n-alkoxy: O(CH2)nH, n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16, or 18) have been prepared following an efficient and practical method. These compounds have been synthesized via the condensation reaction of hydrazine hydrate and appropriately 4-(n-alkoxy) benzaldehydes in acidic medium under ambient conditions. The prepared organic compounds have been characterized and their structures were elucidated depending upon micro-elemental analysis and spectral data (IR, UV-Vis, 1HNMR, 13C{1H}NMR, 2D 1H-1H-cozy, 2D 1H-13C-HSQC, and mass spectra). Liquid crystalline behavior of the prepared compounds was studied using polarized light optical microscopy and differential scanning calorimetry techniques. This study revealed that all the compounds displayed enantiotropic liquid crystal properties, exhibiting smectic and nematic mesophases.

Journal ArticleDOI
TL;DR: In this article, microfluidics generated liquid crystal (LC) droplets are used as microresonators in optofluidics applications due to their small size, narrow droplets diameter distributions, high Q-facto...
Abstract: Microfluidics generated liquid crystal (LC) droplets are currently used as microresonators in optofluidics applications due to their small size, narrow droplets diameter distributions, high Q-facto...

Journal ArticleDOI
TL;DR: In this paper, the deformation behavior demonstrated by current liquid-crystalline elastomers (LCEs) matrices has been investigated and shown to possess large and equilibrium reversible anisotropic dimensional change in response to applied stimuli.
Abstract: Liquid-crystalline elastomers (LCEs) possess large and equilibrium reversible anisotropic dimensional change in response to applied stimuli. The deformation behavior demonstrated by current LCE mat...

Journal ArticleDOI
Abstract: Thirteen carboxylic acid derivatives containing 1,3,4-thiadiazole ring in their core and swinging alkoxy terminal were synthesized. They were characterized by 1H, 13C NMR spectroscopy, FTIR, and ma...

Journal ArticleDOI
TL;DR: In this paper, a homologous series of seven linear hydrogen bonded thermotropic liquid crystals are isolated from p-n-octyloxy benzoic acid (8BAO) and pn alkyl benzosic acids (nBA), where n varies from 2 to 8.
Abstract: A homologous series of seven linear hydrogen bonded thermotropic liquid crystals are isolated from p-n-octyloxy benzoic acid (8BAO) and p-n alkyl benzoic acids (nBA, where n varies from 2 to 8). In all the seven complexes, hydrogen bonding is a result of complementary proton-donor and electron-acceptor pairs derived from carboxylic acids of 8BAO and nBA. Spectroscopic characterization such as Fourier Transform Infrared spectroscopy (FTIR) and Nuclear Magnetic Resonance (1HNMR, 13CNMR) are performed for all the seven complexes to confirm the intermolecular hydrogen bonding and the nature of chemical environment respectively. Seven mesogen are examined by Polarizing Optical Microscope (POM) for identification of the phase polymorphism through standard textures. Transition temperatures and corresponding enthalpy values of the individual mesogenic phases are experimentally obtained from the analysis of the respective Differential Scanning Calorimetry (DSC) thermograms. Phase diagram of this homologous...

Journal ArticleDOI
TL;DR: In this article, the results of experimental investigations of polymer dispersed cholesteric liquid crystals (PDCLC) are represented, and an optical fiber temperature sensor with successive allocations of primary transducers and shifted areas of selective reflection band has been designed.
Abstract: The investigations of system based on cholesteric liquid crystal (CLC) sensors of physical quantities with an information transfer optical channel are carried out in the paper. The results of experimental investigations of spectral characteristics of polymer dispersed cholesteric liquid crystals (PDCLC) are represented. The application such material as primary transducer of a temperature sensor is proposed. The structure of an optical fiber temperature sensor with successive allocations of primary transducers and shifted areas of selective reflection band has been designed.

Journal ArticleDOI
TL;DR: In this paper, the authors used spray pyrolysis technique and annealed in air to obtain the characteristics of CZTS thin films at annealing temperatures of 350-550°C in increments of 50°C for durations of 1, 2, and 3 min.
Abstract: Cu2ZnSnS4 (CZTS) thin films were manufactured using spray pyrolysis technique and annealed in air. The characteristics of these films manufactured at annealing temperatures of 350–550°C in increments of 50°C for annealing durations of 1, 2, and 3 min were studied using X-ray diffraction, field-emission scanning electron microscopy (FE-SEM), ultraviolet-visible near-infrared (UV-Vis-NIR) spectrometer, and Hall effect measurements. Experimental results showed that the best CZTS film is a film annealed at 500°C for 1 min, which had moderate properties for manufacturing a solar cell device; its band gap energy, volume carrier concentration, mobility, and resistivity were 1.46 eV, 1.22 × 1019 cm− 3, 1.963 cm−2/Vs, and 0.283 Ωcm, respectively.

Journal ArticleDOI
TL;DR: In this paper, a nonlinear optical material benzoyl valine (BV) was synthesized by the technique of slow evaporation process at room temperature using a single crystal X ray diffraction analysis.
Abstract: A nonlinear optical material benzoyl valine (BV) was synthesized by the technique of slow evaporation process at room temperature. The single crystal X ray diffraction analysis evince that crystal ...

Journal ArticleDOI
TL;DR: In this article, the crystal structure has been determined by X-ray diffraction technique and the IR, NMR and PL were used to synthesize the sulfapyridine complex.
Abstract: Silver complex of sulfapyridine has been synthesized and characterized by IR, NMR and PL. The crystal structure has been determined by X-ray diffraction technique. Silver complex of sulfapy...

Journal ArticleDOI
TL;DR: In this paper, the hybrid material of magnetic graphene oxide (MNPs/GO) was prepared with a facile route and adsorption properties for removal of methylene blue (MB) were investigated.
Abstract: The hybrid material of magnetic graphene oxide (MNPs/GO) was prepared with a facile route and adsorption properties for removal of methylene blue (MB) were investigated. Initially, the surface of m...