LIQUID CRYSTALS
·
2012
·
IF 1.858
Fafu Yang,Jianwei Xie,Hongyu Guo,Bingting Xu,Congcong Li
Series of novel 1,3,5-triazine-based triphenylene oligomers 7, 10 and 12 with large bridging polyaromatic core were designed and synthesised by simple procedures in high yields. Their structures were confirmed by FTIR, 1H NMR, ESI-MS and elemental analyses. Their mesomorphic behaviours were studied by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. 1,3,5-triazine-based triphenylene monomer 7 has no mesomorphic property, but 1,3,5-triazine-based triphenylene dimer 10 and 1,3,5-triazine-based triphenylene trimer 12 possess excellent mesomorphic properties. The mesomorphic temperature range of compound 12 was as wide as 180°C. These studies indicated that the mesomorphic properties were determined by the numbers of triphenylene units. More units of triphenylene in the oligomers resulted in better mesomorphic properties.
研究领域:
材料科学
·
化学
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产品关联
DOI
高影响因子
LIQUID CRYSTALS
·
2019
·
IF 3.078
Xiaodong Wang,Lu Bai,Shengwen Kong,Ying Song,Fanbao Meng
Series of novel star-shaped liquid crystals containing [1,1ʹ-biphenyl]-4,4ʹ-diyl diisonicotinate mesogens with various counterions (Br−, B-SO3−,C-SO3−,H2PO4−, BF4−) have been synthesized and characterized, which display a nematic phase. The molecular structures of the liquid crystals, thereof consisting of rod-like mesogens linked together by different long alkyl spacers to a small disc-like core of central benzene-1,3,5-triyl triisonicotinate, have been fully characterized by 1H NMR. Their thermal and supramolecular organization behaviours have been studied by combining polarized optical microscopy, differential scanning calorimetry and small-angle X-ray scattering. These investigations showed that the mesophase temperature range increased with increasing alkyl chain length and the clearing point decreased with increase of anion size. These star-shaped liquid crystals have a long and ordered molecular structure, the electron delocalization of the π-π stacking conjugation effect and the electrostatic attraction of ionic make them have good ferroelectric properties and ionic conductivity properties. The interest in preparing ionic liquid crystal with a nematic phase lies in the technological applications as it is well known that the nematic phase has the highest fluidity of all liquid crystalline phases and hence the possibility to align it by applying an external electric/magnetic field, commonly used in electro-optical devices.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
Coatings
·
2023
·Vol. 13
·期 1
·168
·
IF 3.4
Han Wu,Ying Jiang,Wenjing Hu,Sijing Feng,Jiusheng Li
To develop a high-performance additive that can meet different operating conditions, three liquid crystals (LCs) were developed as additives for a base oil. The structures and thermal stabilities of the obtained LCs were characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy, mass spectroscopy (MS), and thermogravimetric analysis (TGA). The effects of mesogenic-phase temperature ranges on tribological properties were analyzed using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). UMT-TriboLab friction and wear tester was used to study the friction-reducing properties of LCs. The width of wear marks was observed by a Contour GT-K 3D profiler to illustrate the anti-wear performance of LCs. The friction surface was characterized by scanning electron microscopy (SEM) and Raman spectroscopy. It was demonstrated that, in comparison with the base oil, the addition of LCs caused a remarkable reduction in the coefficient of friction (21.57%) and wear width (31.82%). In addition, LCs show better tribological abilities in the mesogenic-phase temperature ranges. According to the results, we demonstrated that LCs can be used as lubricant additives, especially for several operating conditions under specific temperatures.Keywords:liquid crystals;mesogenic-phase temperature ranges;lubricant additives;tribological property
研究领域:
材料科学
·
机械工程
✓ 已验证
产品关联
DOI
高影响因子
Polymer Chemistry
·
2021
·Vol. 12
·期 5
·736-743
·
IF 5.582
Enjie He,Kai Tu,Jiannan Cheng,Huanjun Lu,Lifen Zhang,Zhenping Cheng,Xiulin Zhu
Main-chain liquid crystalline polymers seldom develop into a columnar phase, let alone mesophase transitions between the columnar phase and other phases as the temperature changes. Herein, we present a new series of main-chain liquid crystalline copolymers which consist of strictly alternating rod-like aryl ester core, alkyl chain and perfluoroalkyl segments synthesized by photoinduced step transfer-addition and radical-termination (START) polymerization. The mesophases can be adjusted by changing the length of alkyl chains or perfluoroalkyl segments, which have been fully investigated and simulated in terms of molecular arrangements of molecules. Importantly the resultant liquid crystalline copolymers can present rare reversible phase transitions from a hexagonal columnar phase to a rectangular columnar phase and finally to a smectic phase with temperature increasing.
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
·
2020
·
IF 2.908
Jiazhen Dang,Shenghua Du,Liyuan Ren,Mengting Zhang,Pei Chen,Aiai Gao,Weisong Du,Xinbing Chen,Zhongwei An
Heterocyclic mesogenic compounds are one of the interesting liquid crystals. Here, a series of 1-methyl-1H- benzimidazole-based mesogenic compounds incorporating ethynyl moiety, 2-[4-[2-[4-(alkoxy)phenyl]ethynyl]phenyl]-1-methyl-1H-1,3-benzimidazole derivatives (nPEPMx) with terminal groups of H, CH3 and NO2 (coded as nPEPMH, nPEPMM and nPEPMN, respectively), are synthesised and their properties are evaluated. It is noted that the compounds nPEPMx with short alkoxy chain less than 9 carbon atoms display enantiotropic nematic mesophases, whereas corresponding reference compounds without ethynyl moiety have enantiotropic smectic mesophases. The mesophase ranges of compounds nPEPMx 50–70°C and 55–108°C on heating and cooling for nPEPMH, 76–106°C and 98–142°C for nPEPMM, and 78–132°C and 130–166°C for nPEPMN, respectively. Besides, compounds nPEPMx show obviously large birefringence of 0.501–0.641, suggesting a potential application in liquid crystal mixture. The high birefringence may result from its large π-conjugated molecule structure incorporating ethynyl and benzimidazole π-conjugated mesogenic unit.
研究领域:
材料化学
·
液晶科学
·
有机合成化学
✓ 已验证
DOI
高影响因子
CHEMISTRY-A EUROPEAN JOURNAL
·
2015
·Vol. 21
·期 9
·3671-3681
·
IF 5.731
Bin Wu,Keyang Chen,Yuchen Deng,Jian Chen,Chengjie Liu,Rongshi Cheng,Dongzhong Chen
Graphical Metalloporphyrin liquid crystals : Well-organized hexagonal columnar mesophases of broad temperature ranges have been achieved in metal complexes of easily available fatty acid octaester substituted porphyrins. The liquid crystallinity of the free base and the metal porphyrins can be tuned with variant length side-chain substituents and different coordinated metal ions (see figure; TPP=tetraphenyl porphyrin). A series of meta -substituted fatty acid octaester derivatives and their transition-metal complexes of meso - tetraphenyl porphyrins (TPP-8OOCR, with R=C n −1 H 2 n −1 , n =8, 12, or 16) have been prepared through very simple synthesis protocols. The thermotropic phase behavior and the liquid crystalline (LC) organization structures of the synthesized porphyrin derivatives were systematically investigated by a combination of differential scanning calorimetry (DSC), polarized optical microscopy (POM), and variable-temperature small-angle X-ray scattering/wide-angle X-ray scattering (SAXS/WAXS) techniques. The shorter octanoic acid ester substituted porphyrin (C8-TPP) did not show liquid crystallinity and its metal porphyrins exhibited an uncommon columnar mesophase. The lauric acid octaester (C12-TPP) and the palmitic acid octaester (C16-TPP) series porphyrins generated hexagonal columnar mesophase Col h . Moreover, the metal porphyrins C12-TPPM and C16-TPPM with M=Zn, Cu, or Ni, exhibited well-organized Col h mesophases of broad LC temperature ranges increasing in the order of TPPNi
研究领域:
材料化学
·
有机化学
·
生物仿生材料
✓ 已验证
产品关联
DOI
PubMed
高影响因子
LIQUID CRYSTALS
·
2015
·
IF 2.486
Kun Hu,Pei Chen,Qiang Weng,Dingqian Shi,Ran Chen,Xinbing Chen,Zhongwei An
By modifying the molecular dipole moments with lateral monofluorine substituent, improved mesophase stabilities were obtained for novel benzoxazole derivatives, 2-(4ʹ-alkoxy-3-fluorobiphenyl-4-yl)-benzoxazole liquid crystals (coded as nPPF(3)Bx). The series of nPPF(3)Bx with lateral monofluorine substituent ortho to benzoxazole group have larger calculated dipole moments by about 2 D than the corresponding fluorine-substituted analogs (compounds I) with lateral monofluorine ortho to alkoxy group; it is interesting to note that they show lower melting and clearing points but better mesophase stability with wider mesophase ranges for the molecules with both polar (NO2, Cl) and nonpolar (CH3, H) terminal groups. Meanwhile, compounds nPPF(3)Bx show greater red-shifted photoluminescence emissions than compounds I, which suggest that π–π interaction between molecules is reinforced by the enhanced dipole–dipole interaction caused by increased dipole moments. These results suggest that modification of the molecular dipole moment is an effective method to improve the mesophase stability of the classical mesogenic compounds.
研究领域:
材料化学
·
物理化学
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产品关联
DOI
高影响因子
LANGMUIR
·
2019
·
IF 3.683
Yiming Gao,Ying Jiang,Wenjing Hu,Haizhen Jiang,Jiusheng Li
Mechanical operation could be seriously affected by friction and controlling it by oil lubrication has been considered as an effective way. Good lubricant additives are very necessary to avoid the friction damages, and to find or design new additives is always a challenge. In this study, a systematic investigation of using cholesteryl liquid crystals (LCs) as lubricant additives to obtain exceptional tribological behaviors was performed. In total, four cholesteryl LC compounds were synthesized targetedly and their thermal and mesogenic properties were studied to see the inherent relationship between the mesogenic phases and antifriction and antiwear performance. Through a series of tribological and related tests, including the UMT TriboLab test, three-dimensional optical microscopy, oil film thickness and viscosity tests, etc., the effect of the mesogenic phases and structures of the synthesized cholesteryl LCs on their tribological properties as lubricant additives was investigated and a related mechanism was analyzed. The result showed that within and close to the mesogenic phase temperature ranges, which we called as effective temperature ranges of LC additives (TEF), the LCs presented better tribological behaviors, meaning they could be used in special lubrication applications that need to be confined in certain temperature scopes; however, the ester groups with long alky tails could help dissolve in base oils and adsorb onto the friction pairs. Among the four LCs, LC-D with a long perfluoroalkyl tail brought widest mesogenic phase with considerably enhanced lubrication performance and increased oil film thickness, viscosity, and thermal stability, indicating that the perfluoroalkyl group could be well used in the structural modification of LC additives to give unexpected tribological performance. This study, in conjunction with our experimental data, suggested that the liquid crystals may be evaluated as potential friction modifiers for temperature-controllable lubrication and also shed a fresh light on the development of novel liquid crystal lubrication materials.
研究领域:
材料科学
·
摩擦学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SOFT MATERIALS
·
2013
·
IF 1.429
Fafu Yang,Lihong Zhang,Bingting Xu,Xiaoyuan Su,Hongyu Guo
The syntheses of novel triphenylene-ferrocene dyads linked by long or short chain containing conjugated structures were reported in good yields. Their electrochemical properties and mesophase behaviors were investigated by cyclic voltammetry, differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction, respectively. Triphenylene-ferrocene dyad with long chain containing conjugated structure 5 possessed redox property but no mesomorphic property. Triphenylene-ferrocene dyad with short chain containing conjugated structure 7 exhibited not only reversible electrochemical response property but also ordered hexagonal columnar mesophase for the first time.
[Supplementary materials are available for this article. Go to the publisher's online edition of Soft Materials for the following free supplemental resource(s): First Triphenylene-Ferrocene Dyad with Redox Behavior and Mesomorphic Property]
研究领域:
材料科学
·
电化学
·
分子设计与合成
✓ 已验证
DOI
高影响因子
LIQUID CRYSTALS
·
2019
·
IF 3.078
Qiang Weng,Longyan Duan,Pei Chen,Aiai Gao,Xinbing Chen,Zhongwei An
Modifying the position and numbers of lateral fluorine substituent is a common method to design and adjust the mesophase of liquid crystal compounds. Here, a series of 2-(2,2ʹ-difluoro-4ʹ-alkoxy-1,1ʹ-biphenyl-4-yl)-5-substituted benzoxazole with both non-polar (H, CH3) and polar (NO2) groups (coded as nPF(2)PF(2)Bx) is synthesised and characterised. All of the compounds show a conspicuous inter-ring twist angle of 38° compared with corresponding reference compounds I and II which are calculated by density functional theory method, and it is interesting to note that the final compounds nPF(2)PF(2)Bx show only nematic mesophase during heating or cooling. Meanwhile, the UV-vis absorption bands and photoluminescence emission peaks both display remarkable blue-shifted. The aforementioned results reveal that lateral difluoro substituents play a key role to stable the nematic mesophase by increasing the dihedral angle of biphenyl.
研究领域:
材料科学
·
化学
·
液晶
✓ 已验证
DOI
高影响因子
APL Materials
·
2024
·Vol. 12
·期 9
·
IF 5.3
Yang Nengjie,Huang Yuting,Dong Chen,Sun Chi,Xi Peipei,Dai Yuexiao,Zhao Rui,Wang Yunan,Zhu Yujuan,Gu Zhifeng
Psoriasis is an immune system-mediated skin disease identified by the appearance of erythematous as a central symptom. As a recurrent and chronic inflammatory disease, psoriasis is influenced by both genetic and environmental factors and is known to be with no effective cure. Considering a multifaceted etiology of psoriasis, synergistic therapy exhibits great benefits over monotherapy, which becomes common for the treatment of various diseases. Herein, we present the nanozyme microspheres with structural color-coding labels for synergistic therapy of psoriasis. In particular, microsphere hydrogel is fabricated by the edible hydroxypropyl cellulose (HPC), which can generate a photonic liquid crystalline mesophase under lyotropic conditions in solution. Through adjustment of hydrogel components, microspheres endow with different functions, including moisturizing (paraffin), cfDNA scavenging (chitosan), and anti-inflammation (cerium oxide nanozyme). To improve patient convenience, hydrogel drops with different properties are tailored with different vivid structural colors by exploiting the lyotropic behavior of HPC. Of particular note, both in vitro and in vivo experiments have demonstrated the significant therapeutic effects of the encoded structural color microspheres. Green moisturizing microspheres facilitate to relieve dry, flaky skin patches; blue cfDNA scavenging and red anti-inflammatory microspheres significantly reduce skin inflammation. More importantly, combination therapy with encoded microspheres exerted the synergistic effects, including the increased body weight, thicker epidermal layer, and reduced immune activation. Overall, this synergistic treatment offers a promising platform for personalized management of psoriasis and various inflammatory skin diseases.
研究领域:
纳米技术
·
药学
·
皮肤科
·
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
DYES AND PIGMENTS
·
2018
·
IF 3.767
Shengjie Jiang,Jiabin Qiu,Yunxiang Chen,Hongyu Guo,Fafu Yang
A series of novel tetraphenylethylene aromatic acylhydrazone derivatives 11 , 12 and 13 with 4, 8 or 12 alkyl chains were designed and synthesized in yields of 82–85%. Studies on the mesomorphic properties suggested the ordered hexagonal columnar mesophase for compounds 11 , 12 and 13 . The increase in the number of alkyl chains was favourable for decreasing the phase-transition temperatures and extending the mesophase temperature range. Further, samples 11 , 12 and 13 presented an excellent AIE effect. The fluorescence intensities increased by 70, 84 and 43 times for samples 11 , 12 and 13 , respectively. The absolute fluorescence quantum yields were 18.7%, 27.4% and 23.8% in solid films at room temperature and 6.7%, 24.2% and 17.3% in the mesophase. These results suggested that the number of alkyl chains greatly influenced the fluorescence emission and sample 12 with 8 alkyl chains exhibited the strongest fluorescence emission. Sample 12 also displayed the electroluminescence performance on OLED device.
研究领域:
材料科学
·
化学
·
光电
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）