Papers by Keyword: Liquid Crystal

Abstract: For the purpose of developing liquid crystalline micro-actuators, the transient behaviors of a nematic liquid crystal between two parallel plates have been computed for various parameters such as applied voltage, the gap between the plates, and the twist and tilt angles at the plates. The Leslie–Ericksen theory has been selected as a constitutive equation. As conclusion of this study, we can develop micro-actuators with arbitrary characteristics by suitably controlling the applied voltage, the size of the actuators, and the director anchoring conditions.

Abstract: For recycling liquid crystal from waste LCD with high value, the method based on supercritical CO₂ fluid technology is proposed. The principle of extracting liquid crystal using supercritical CO₂ fluid is analyzed and the factors influencing liquid crystal recycling effect are discussed. The solubility of supercritical fluid is enhanced by adding polar entrainer in order to raise the recycling rate. The procedure for recycling liquid crystal with supercritical fluid technology is studied. Choosing TFT mode LCD as researching object, selecting different temperature and pressure and adopting isothermal and depressurization method, a series of recycling experiments are completed. The results show that the recycling rate of liquid crystal can reach 90% with the aid of supercritical carbon dioxide fluid technology and the purity and recycling efficiency of liquid crystal are high.

Abstract: The model of thermal effect for liquid crystal director was built. The temperature field of liquid crystal was numerically studied. The effects of laser irradiation time and the crystal size on the thermal effect were analyzed and compared. With the increase of laser irradiation time, the temperature field became stable.

Abstract: A kind of novel liquid crystalline monomer containing double photosensitive groups which were azo and chalcone groups was synthesized. The structures of the intermediates and the final monomer were confirmed by FT-IR and 1H NMR spectra. The thermal properties of monomer were measured by DSC and the liquid crystalline texture was measured by polarized optical microscopy. And the results indicated that the monomer showed nematic phase and liquid crystal temperature range was 150.8-186.5oC.

Abstract: Two kinds of photo-crosslinkable polymers with a coumarin-containing and cinnamate-containing side group were synthesized in this paper. The structure of the intermediates, monomers and polymers were characterized with FTIR and 1HNMR measurement. Differential scanning calorimetry (DSC), hot stage polarized optical microscopy (POM) were employed to study the phase-transition temperature, mesophase texture. UV-VIS spectrophotometer was used to survey the ultraviolet absorption performance of the polymers. The results showed that the monomer with cinnamate group showed nematic phase and smectic phase over a wide temperature range. What’s more, the ultraviolet absorption peak of the polymer with cinnamate group was at about 285 nm, and the ultraviolet absorption peak of the polymer with coumarin group was around 311.00 nm.

Abstract: A new kind of bowl-shaped liquid crystals were designed and synthesized by esterification. They used a calix[6]arene as central unit and ω- cholesteric alkyl diacid monoester as mesogenic arms. Their chemical structures were confirmed by FTIR and 1HNMR spectra, their mesomorphic properties and phase behavior were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-Ray Diffraction (XRD) measurements. The results showed that the kind of calix[6]arene bowl-shaped liquid crystals N1-N3 exhibited broad range liquid crystalline phases at moderate temperature, and they displayed cholesteric phase focal-conic texture in liquid crystal states. With increasing the flexibility of monomers M1-M3, the melting point and the clearing temperature decreased in the macromolecules.

Abstract: Liquid crystal, as a condensed matter, is a phase state between crystal and isotropic liquid. On the one hand, it has mobility and continuity as a liquid, and on the other hand, it has arranging ordering as a crystal, then it has many unique properties. Because the factors, such as heat, electric field, magnetic field, pressure, and so on, will easily influence the arranging of liquid crystal molecular, so once it is excited externally, its optical properties will be changed. At present, most research on the theory and application of liquid crystal mainly focus on the display. Thermo-optic effect is defined as the phenomenon that the optical properties of liquid crystal change with the changing of temperature. At the phase transition point, the thermo-optic effect of liquid crystal is very obvious. In this paper, non-electric readout infrared thermal imaging detection technology based on the optical rotation property of the cholesteric liquid crystals is mainly researched. Through the research, the cholesteric liquid crystals’ light curves, gray value curves and CCD image were obtained under different temperatures; it proved that using the optical rotation property of cholesteric liquid crystals to achieve the infrared imaging of hot objects is possible.

Abstract: A typical liquid crystal (LC) N,N-(terephthalylidene) bis (4-decylbenzenamine) (TB10A) was firstly synthesized at room temperature. The synthesized LC TB10A were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), ultraviolet-visible (UV-vis) spectrophotometry, photoluminecence (PL) spectroscopy and electronic structure calculations. Upon the 325 nm excitation, the dilute tetrahydrofuran solutions of TB10A could give off blue PL. With Hückel tight-binding method, the electronic structures of the TB10A were calculated. Our results demonstrated that the deep-blue PL observed at about 489 nm (2.54 eV) can be assigned to the π* → n transition for the TB10A.

Abstract: A new type of able liquid crystalline polymer with a coumarin-containing mesogenic side group that could be photo-crosslinked was synthesized in this paper. The structure of the intermediates, monomers and polymers were characterized with FTIR and ¹HNMR measurement. DSC, TG, and hot stage polarized optical microscopy were employed to study the phase transition temperature, mesophase texture, and thermal stability of the liquid crystalline polymers. The results indicated that both the monomer and polymer exhibited liquid-crystalline features over a wide temperature range.

Abstract: A rod-like liquid crystal (LC) N,N-(terephthalylidene) bis (4-n-butylaniline) (TB4A) was synthesized by one step at room temperature. The synthesized TB4A were investigated with nuclear magnetic resonance, fourier transform infrared spectrometer and ultraviolet-visible spectrophotometry, differential scanning calorimetry and polarizing optical microscopy. Our results demonstrated that the TB4A can form nematic, smectic A, smectic C, smectic F and smectic G LC phases.