LIQUID CRYSTALS
·
2017
·
IF 2.661
Longyan Duan,Dingqian Shi,Pei Chen,Kun Hu,Liyuan Ren,Xinbing Chen,Zhongwei An
Series of laterally multifluorinated heterocyclic compounds, 2-(2ʹ,3-difluoro-4ʹ-alkoxy-1,1ʹ-biphenyl-4-yl)-benzoxazole derivatives (nPF(2)PF(3)Bx), are prepared and characterised. They mainly display enantiotropic nematic mesophases with wider mesophase ranges of 12–107°C (heating process) and 22–134°C (cooling process) than the corresponding analogues. The enhanced nematic mesophase stability is achieved via slightly increasing inter-ring twist angle with inter-ring lateral fluorine substitute in biphenyl unit, as well as through improving the molecular polarity with multifluorine substitutes. Meanwhile, two inter-ring lateral fluorine atoms lead to a decrease in melting/clearing points and a wide nematic mesophase range, which makes it possible for heterocyclic mesogens nPF(2)PF(3)Bx to use in nematic liquid crystal display mixtures.
研究领域:
材料科学
·
化学
✓ 已验证
DOI
高影响因子
LIQUID CRYSTALS
·
2013
·
IF 1.959
Jianqiang Xie,Guangming Zhu,Yusheng Tang,Zengping Zhang
Two nematic liquid crystal (LC) monomers containing double bonds in the side chain were designed and synthesised. Length of the side groups varied from 1 to 2 methylene units. The side-chain polymers were synthesised by hydrosilylation reaction. The molecular structures of the intermediates and the LC monomers were characterised by Fourier transform infrared, elemental analysis and nuclear magnetic resonance spectroscopy. The thermal phase behaviour of the monomers and polymers were investigated by differential scanning calorimetry and polar optical microscopy coupled with hot stage. The LC monomers showed only one nematic mesophase in the cooling process. And, the two polymers exhibit an enantiotroppic nematic mesophase either in the heating or in the cooling process.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
LIQUID CRYSTALS
·
2016
·
IF 2.244
Dingqian Shi,Kun Hu,Pei Chen,Aiai Gao,Weisong Du,Ran Chen,Xinbing Chen,Zhongwei An
Fluorine is widely used as a lateral substituent to modify the physical properties of liquid crystals. Here, laterally monofluorinated compounds, 2-(4ʹ-alkoxy-2-fluorobiphenyl-4-yl)-benzoxazole derivatives (nPPF(2)Bx) bearing different substituents (H, CH3, NO2, coded as nPPF(2)BH, nPPF(2)BM and nPPF(2)BN, respectively) at 5-position, were synthesised and characterised. It is interesting to note that these only display enantiotropic nematic mesophases with mesophase ranges of 12–28°C and 13–45°C on heating and cooling for nPPF(2)BH, 46–97°C and 62–120°C for nPPF(2)BM and 82–108°C and 87–113°C for nPPF(2)BN, which are very different from the corresponding monofluorine-substituted analogue (compounds I) with enantiotropic smectic or smectic/nematic mesophases. The enhanced nematic mesophase is attributed to the reduced π–π interaction/conjugation resulting from the twisted structure of the molecule caused by the introduction of a fluorine atom into the inter-ring of the biphenyl unit. These results suggest that modification of the monofluorine substituent position is an effective method to improve the nematic mesophase in benzoxazole-liquid crystals.
研究领域:
材料科学
·
有机化学
✓ 已验证
DOI
高影响因子
PHYSICS OF FLUIDS
·
2024
·Vol. 36
·期 1
·
IF 4.1
Yu Jia-Jia,Jiang Lu-Yang,Huang Li,Li Gu-Yuan,Bake Maitiniyazi,Li You-Rong
Hydrodynamic cavitation, which occurs when the local pressure is below the saturated vapor pressure in hydrodynamic flow, is ubiquitous in fluid dynamics and implicated in a myriad of industrial and biomedical applications. Although extensively studied in isotropic liquids, corresponding investigations in anisotropic liquids are largely lacking. In this paper, the hydrodynamic cavitation in the bluff body bypass flow of nematic liquid crystal 5CB in the microchannel is experimentally investigated. By 5CB, we mean the thermotropic liquid crystal 4′-pentyl-4-biphenylcarbonitrile. When the Reynolds number is in the range of 3 × 10 −4 < Re < 1.2 × 10 −3 , a special flow phenomenon behind the bluff body is observed, namely, the disclination loop. The critical Reynolds number of cavitation inception varies with the shape of the bluff body, while the lowest value corresponds to the triangular bluff body. The hydrodynamic cavitation occurs in the Stokes flow regime with the Reynolds number significantly lower than 0.1 for all bluff bodies. There is a close relation between the oscillation behavior of cavitation domains and the structure of the bluff body. In addition, the pressure difference between the inlet and outlet of the microchannel shows linear relation with the Reynolds number rather than the quadratic relation for isotropic fluids, which proves the presence of shear thinning in the flow of nematic liquid crystals. The study in this paper on the hydrodynamic cavitation of nematic liquid crystal can broaden the research on providing new approaches for the enhancement of fluid mixing and heat transfer in microfluidic chips.
研究领域:
流体力学
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材料科学
·
微流控技术
✓ 已验证
产品关联
DOI
高影响因子
MOLECULAR CRYSTALS AND LIQUID CRYSTALS
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2020
·
IF 0.512
Gege Jin,Yongmin Guo,Limin Wu,Yi Li,Baozong Li,Yonggang Yang
Three series of meta-perfluoroalkylphenol esters are synthesized. Both SmA and SmC phases are identified. Their clearing points increase with increasing the perfluorocarbon chain length, while decrease with increasing the alkoxy chain length. Comparison of the 3-tridecafluorohexylbenzoates and 3-tridecafluorohexylphenol esters, the 3-tridecafluorohexylbenzoates show higher clearing points, indicating that the direction of the ester bond plays an important role in the thermostability of the liquid crystalline phases. Moreover, it was proposed that the compounds with short and long alkoxy chains packed into different structures.
研究领域:
材料化学
·
分子结构研究
✓ 已验证
产品关联
DOI
高影响因子
LIQUID CRYSTALS
·
2016
·
IF 2.244
Dingqian Shi,Kun Hu,Pei Chen,Weisong Du,Aiai Gao,Ran Chen,Xinbing Chen,Zhongwei An
A series of nematic heterocyclic liquid crystals, 2-(2ʹ-fluoro-4ʹ-alkoxy-1,1ʹ-biphenyl-4-yl)-benzoxazole derivatives (coded as nPF(2)PBx) bearing hydrogen (nPF(2)PBH), methyl (nPF(2)PBM) and nitro (nPF(2)PBN) terminal groups, respectively, are developped and investigated. The results show that the nematic mesophase stability is obviously improved via a slightly increase in the inter-ring twist angle between the planes of two phenyl rings in the biphenyl unit, where modification of the twist angle can be achieved by adjusting the position of the lateral monofluorine substituent from the outer to the inter ring of the biphenyl mesogenic core unit. Meanwhile, the inter-ring lateral fluorine substituent results in a decrease in both melting and clearing points but only a nematic mesophase with an acceptably wide mesophase range for nPF(2)PBx, and thus a potential application in liquid crystal display mixtures is expected, especially for the compounds nPF(2)PBM and nPF(2)PBN. The reduced π–π interaction/conjugation caused by the increased twist angle is considered as one of the possible reasons for the formation of a nematic mesophase.
研究领域:
材料科学
·
液晶化学
✓ 已验证
DOI
高影响因子
LIQUID CRYSTALS
·
2020
·
IF 2.908
Shenghua Du,Mengting Zhang,Pei Chen,Jiazhen Dang,Aiai Gao,Weisong Du,Xinbing Chen,Zhongwei An
With altering molecular dipole moments via lateral fluoro atom and π-conjugation through carbon–carbon triple bond, improved mesomorphic behaviour is achieved for new kind of fluorinated mesogenic compounds containing ethynyl and 1-methyl-1H-benzimidazole moieties, namely, 2-[4-[2-[4-(alkoxy) phenyl]ethynyl]-3-fluorophenyl]-1-methyl-1H-benzimidazole derivatives (nPEF(3)PMx). The compounds nPEF(3)PMx mainly display enantiotropic nematic mesophases with mesophase ranges of 27.1–59.1 °C and 62.7–96.7°C on heating and cooling for nPEF(3)PMH, 59.499.1°C and 96.2–144.6°C for nPEF(3)PMM, and 101.6–109.4°C and 104.9–157.2°C for nPEF(3)PMN (n < 8), respectively. Compared with nonfluorinated reference analogues I, nPEF(3)PMx give obviously lower melting points and much wider or comparable nematic mesophase ranges, meanwhile, they show much lower melting points and higher nematic mesophase stability than reference analogues II because of their reduced molecular dipole moments and enhanced π-conjugation. In addition, the compounds nPEF(3)PMx are composed of benzene ring, ethynyl bridge and benzimidazole mesogenic unit, therefore, they have high birefringence of 0.48–0.62 resulted from their large π-conjugated molecule. The result indicates that nPEF(3)PMx has a potential application in liquid crystal mixture.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2022
·Vol. 46
·期 19
·9024-9035
·
IF 3.925
Jun Li,Yuehua Cong,Haozhou Huang,Qiankun Shi,Yinggang Jia,Baoyan Zhang
Multiple mesophases, including the smectic A phase (Sm A), chiral nematic phase (N*), and blue phase (BP I), were seen in a series of non-symmetric bent mesogenic dimers containing a cholesteryl benzoate group. FTIR, 1H-NMR, DSC, POM, UV, and XRD were used to analyze the chemical structure and liquid crystal characteristics of the dimers. The phase transition occurred when the azobenzene structure was treated with UV light, changing the structure of the molecules. There is evidence that when the length of the terminal alkoxy chain is longer than the flexible spacer, it exhibits a smectic A phase as well as a chiral nematic phase; however, when the length of the flexible spacer is shorter than the length of the terminal alkoxy chain, it only exhibits a chiral nematic phase.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
LIQUID CRYSTALS
·
2021
·
IF 0
Hao-Zhou Huang,Yue-Hua Cong,An Du,Bing Hu,Bao-Yan Zhang
A new series of liquid crystalline dimers containing a cholesteryl group were synthesised, exhibiting multiple mesophases including chiral smectic phases (SmC* and SmA*), twist grain boundary phases (TGBA*), and chiral nematic phase (N*). The chemical structure and liquid crystal properties of the dimers were characterised by FTIR, 1H-NMR, DSC, POM and XRD. It was in evidence that the lengths of the terminal tail and the flexible spacer were the decisive factors of the mesophase behaviours.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
LIQUID CRYSTALS
·
2021
·
IF 0
Baining Ni,Yu Cao,Hongkun Li,Wei Liu,Baozong Li,Yi Li,Yonggang Yang
Structural coloured materials have been widely found in nature. More and more artificial materials were created based on structural colour. However, fabrication of polymer films with pearly lustre remains a challenging task. Herein, a strategy is reported to prepare broadband reflection polymer films based on the fluorophilic association. A monomer with a perfluorooctyl chain is synthesised. After photo-crosslinking a mixture of a chiral nematic liquid crystal and the fluorinated monomer, broadband reflection film with pearly lustre is obtained. The broadband reflection originates from the broad distribution of the helical pitch. The pearly lustre is caused by the periodically ordered layers formed by the microphase separation between hydrocarbon and fluorocarbon chains.
A strategy for the preparation of color liquid crystal polymer film with pearly luster is developed. The Bragg-reflection color originates from the supramolecular helical structure of the cholesteric liquid crystal and the pearly luster originates from the multilayer structure formed by the fluorocarbon/hydrocarbon microphase separation
研究领域:
材料科学
·
光学
✓ 已验证
DOI
CARBOHYDRATE POLYMERS
·
2024
·
IF 10.7
Mingfeng Wu,Huan Wang,Afroza Akter Liza,Lukuan Guo,Wenyuan Zhu,Junlong Song,Fengshan Zhang,Yanshao Liu,Yongcan Jin,Jiaqi Guo
3D printing technology is one of the most promising strategies for constructing topological functional materials. The development of functional inks is a core issue in the technical development of 3D printing technology. In this study, we engineered photonic crystal inks based on chiral nematic liquid crystals of cellulose derivative, i.e. hydroxypropyl cellulose (HPC), and applied it to direct-ink-writing (DIW) 3D printing technology. We modified hydroxypropyl cellulose by etherification reaction to obtain photo-cross-linkable water-soluble hydroxypropyl cellulose acrylate (HPCA) with different degrees of substitution (DS). We comprehensively explored the effect of the DS on the initial concentration of formed chiral nematic liquid crystal and quantitatively, analyzed the relationship between the DS and the helical structure of the chiral nematic structure. We used photo cross-linkable chiral nematic HPCA as photonic crystal ink to construct structure-color 3D objects of diverse shapes. The constructed structure-color objects showcase robust tolerance against temperature and acidic conditions (pH = 1). Moreover, the color of the constructed objects is independent of the observation angle. The photonic crystal ink based on chiral nematic liquid crystals of biodegradable polysaccharide materials is expected to have excellent market prospects in the fields of such as smart packaging and optical devices.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
POLYMER
·
2018
·
IF 3.483
Wenbo Shen,Ling Wang,Tingjun Zhong,Gang Chen,Chunxin Li,Mei Chen,Cuihong Zhang,Lanying Zhang,Kexuan Li,Zhou Yang,Huai Yang
In this paper, we report the design, preparation and properties of epoxy-mercaptan polymer/nematic liquid crystal (LC) composites with electrically switchable optical transmittance. It is found that the polymer microstructure can be regulated from porous structure to microspheres or beads by appropriately modulating the curing temperature, the molecular structure of mercaptan, as well as the compositions of epoxy, mercaptan and nematic LC host. Under an external electric field, the thin films based on such composites can switch from opaque to transparent. The electro-optical performance is found to be highly dependent on the polymer microstructures and the optimum characteristics can be achieved in the composite with a microstructure of smaller microspheres. The possible mechanism for the formation of polymer microspheres and the effects of the microstructures on the electro-optical characteristics of the composites are also discussed. This work is expected to provide an efficient way to control the microstructure of epoxy/mercaptan polymer and develop the composites with switchable optical transmittances for both civil and military applications.
研究领域:
材料科学
·
光学工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）