Papers by Keyword: Liquid Crystal

Abstract: This study investigates the intricate inter- and intra-molecular interactions that govern the range and nature of mesophases observed in homologous series of liquid crystalline materials. Using computational modelling, we compared the results with reported experimental values for several members of the series. Our analysis focused on various parameters, including lattice energy, orientational order parameter, moduli, stress-strain behaviour, Helmholtz free energy, orientational distribution function, zero-point energy, and molecular polarizabilities. Our findings reveal a strong correlation between the computational results and experimental data, providing valuable insights into the mesophases of these compounds. This alignment underscores the significance of our approach in understanding the fundamental behaviors of liquid crystalline materials.

Abstract: Liquid crystal-quantum dot (LC-QD) composites are promising new materials for a number of applications in displays, energy harvesting, and photonics. In the present work, quantum dispersion in the mixture of LCs of cholesteric and nematic phases is reported. The combination of two LCs, namely Cholesteryl Palmitate (cholesteric 97%) and 4′-Pentyl-4-biphenylcarbonitrile (nematic, 98%), were used in equal proportion while CdS quantum dots were added in this mixture. The thermal, optical, and structural properties of this new LC-QD composite system were analyzed using differential scanning calorimetry (DSC), ultra-violet visible (UV-VIS) spectroscopy, Fabry-Perot scattering studies (FPSS), and Fourier transform infrared (FTIR) spectroscopy. Structural studies indicate that the QDs are uniformly dispersed inside the LC matrix rather than on the surface area. It was observed that quantum dot dispersion increases the strength of the LC mixture. It also changes the phase behavior of the LC mixture affecting the overall performance of LC-QD composite systems. The present findings would be very helpful for the design of the display and photonic devices with an improved optical response.

Abstract: Poly hydroxyethyl methacrylate (p-HEMA) has a natural property that is very easy to absorb a liquid or solution and become a hydrogel when absorbing water. In this work, by combining p-HEMA material with a cholesteric liquid crystal (CLC), the material can absorb the solution and the optical properties of the liquid crystal will change depending on the solution it absorbs. The solution used in this work is acetone. During the absorption process the p-HEMA material expanded so that the orientation direction of liquid crystal molecular twist with a helical axis along can freely move and change. In this work, we observed the study of transmittance caused by thickness effect and the mixture concentration effect of the poly hydroxyethyl methacrylate liquid crystals (PHM-LC).

Abstract: In this paper, the latest techniques and technologies of liquid crystal devices have been reviewed with essential conclusions made based on their applications. This work combines Liquid Crystal research from different field. Here I give an overview of Liquid Crystal instrumentation in the optical systems, focusing on a large domain of applications: photonic devices, biomedical applications, etc. I characterize common approaches and challenges. In addition, novel technique of liquid crystal that permits a new solution has been presented. I conclude with advice regarding the Liquid Crystal group at large to make concerted efforts to exchange expertise.

Abstract: In this work, liquid crystal emulsion with aloe vera (AV) was formulated and characterised its physical properties. A direct titration method was used to determine the composition of liquid crystal emulsion in a system consisting of water/mixed Tween 80: Span 85/hexane. AV gel was added to produce AV liquid crystal emulsion (AVLCE), which was then subjected to various characterisation such as microscopic analysis, stability test, rheological test and particle size analysis. Results showed that the application of AVCLE employed better performances in terms of stability, particle size and moisturizing. This study suggest that the formulated AVLCE may be suitable to be used as topical application on wounded skin.

Abstract: A novel triphenylene-based discotic liquid crystal 2, 3, 6, 7, 10, 11-hexabutylcarboxyltriphenylene was synthesized. The chemical structure was determined by ¹HNMR and FT-IR spectrum, and its mesophase was investigated by DSC and POM methods. The compound showed classical texture of columnar plastic phase under POM at the mesophase temperature from175°C-185°C during cooling.

Abstract: We introduce a new self-separation of graphene oxide flakes exploiting liquid crystalline phase formation. Moderately concentrated discotic GO aqueous solution spontaneously phase separates into isotropic phase and nematic phase. According to Onsager theory, larger flakes with higher aspect ratio tends to form nematic phase, while smaller flakes remain in isotropic phase. Simple isolation of bottom nematic phase (large graphene oxide; LGO) resulted in the LGO dominant dispersion preparation. We employed this size selection principle to investigate the influence of GO flake size upon the material properties of reduced graphene oxide. The electrical properties of spin cast rGO films are thoroughly investigated in terms of the GO flake sizes in the precursor aqueous dispersions. Interestingly, nitrogen doping in order to inject more electron charge carrier exhibit different behavior following flake size. Therefore, it was experimentally confirmed that quaternary nitrogen doping site acts as the dominant catalytic site in oxygen reduction reaction.

Abstract: Liquid crystal was formed in a ternary system of tetraethylene glycol lauryl ether, water and 1-ethyl-3-methylimidazolium hexafluorophosphate. Its structure was identified by polarized optical microscopy and small-angle X-ray scattering techniques. Compared to that in the binary system, lamellar phase was retained with the addition of a small amount of imidazolium salt. Molecules of 1-ethyl-3-methylimidazolium hexafluorophosphate were considered to be solubilized in the polar domain of the ordered assemblies. Results on their influence on the lamellar phase enlighten the use of imidazolium salts to modulate liquid crystalline materials and other assemblies.

Abstract: The synthesis of a new liquid crystal thiophene monomer of (E)-4-(6-(3-(thiophen-3-yl)- acryloyloxy) hexyloxy) biphenyl-4’-ethylbenzoate (LC-M) is presented. The chemical structure of this monomer and intermediate compounds was characterized by FT-IR and ¹H-NMR. The phase behavior was investigated by polarizing optical microscopy and differential scanning calorimetry. LC-M showed nematic threaded and schlieren textures on heating and cooling cycles.

Abstract: In order to obtain an important azobenzene liquid crystal with high birefrience, click chemistry reaction was used to preparation the compound. In this paper, the novle azobenzene liquid crystal was synthesized by (4-Ethynyl-phenyl)-(4-trifluoromethyl-phenyl)-diazene and C₈H₁₇Br as raw materials. In addition, the synthesized compound was characterized by FT-IR and ¹H-NMR to confirm the consistent structure, and the liquid crystal phase behaviors of phase sequences were investigated by polarizingmicroscope (POM).