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新型含酰胺键的噻二唑类液晶的合成 总被引:16,自引:0,他引:16
合成了以酰胺键为中心桥键的1,3,4-噻二唑衍生物3个系列共16个新化合物。液晶性质测试表明,它们均为具有高相变温度和宽相变范围的稳定液晶化合物。说明极性的酰胺键有利于介晶性能。比较了端某碳原子数目的多寡对Sc相相变温度的影响。 相似文献
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为有效降低液晶器件的开启电压,获得具有低功耗特性的液晶显示器件。本文采用巯基功能化的笼形倍半硅氧烷(POSS)作为修饰配体,硼氢化钠为还原剂,采用一步法还原氯金酸制备出粒径约为5 nm的金纳米粒子。将该金纳米粒子以不同质量分数掺杂到向列相液晶4-正戊基4'-氰基联苯(5CB)中,研究了其对液晶黏度、阈值电压、相变温度的影响。结果表明,POSS修饰的金纳米粒子可以使液晶材料5CB的黏度降低、阈值电压减小。该金纳米粒子的掺入,拓宽了液晶材料的相变温度范围。 相似文献
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卟啉液晶作为一种功能型盘状液晶,已经受到了科学家们的高度重视^[1]。自1980年Goodby^[2]首次合成出简单的卟啉液晶以来;各国学者对卟啉液晶的合成做了相应的研究工作,但其液晶相变温度偏高^[3,4],相区宽度偏窄^[3]。本文首次合成出相变温度较低,相区宽,含有8,10,12和14碳的酰氧基的四种卟啉液晶5、10、15、20-四(对-酰氧基)苯基卟啉液晶5、10、15、20-四(对-酰氧基)苯基卟啉锌(Ⅱ)配合物[分别简称为TOPPZn,TDPPZn,TLPPZn,TMPPZn]。研究4种配合物的液晶行为,其液晶相相变温度最低始于-36.4℃,相区宽达175℃,是一种具有应用前景的卟啉液晶。 相似文献
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用环氧乙烷低聚物为柔性间隔的手性侧链液晶高分子的合成 总被引:5,自引:0,他引:5
本文用乙氧基做为主链与侧链的柔性间隔,合成了手性侧链液晶高分子.通过DSC,热台偏光显微镜及X-衍射等手段,研究了柔性间隔链长对液晶行为的影响.结果表明,这类液晶高分子有较宽的相变温度范围.聚合物的相变温度及液晶态的形成与柔性间隔链长有关. 相似文献
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反铁电性液晶化合物研究现状 总被引:7,自引:0,他引:7
综述了反铁电性液晶近年来的研究现状, 讨论了反铁电性液晶结构中各部分对液晶相变行为和电光性能的影响, 简要论述了反铁电性液晶今后的研究方向。 相似文献
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基于定向电纺纤维膜的可调制偏振片的制备 总被引:2,自引:1,他引:1
基于定向静电纺丝技术制备了高取向性有序纤维薄膜, 利用有序纤维对液晶分子取向的诱导, 构建了可调制散射型偏振片. 填充混合液晶的有序聚甲基丙烯酸甲酯纤维薄膜在可见光范围内, 表现出明显的偏光特性. 混合液晶中光敏性偶氮液晶4-正丁基-4'-甲氧基偶氮苯在360 nm紫外光照射下进行顺反异构转变, 诱导混合液晶发生从各向异性到各向同性的相变. 利用混合液晶光致相变与有序纤维的耦合, 实现了薄膜偏光特性的光控切换. 相似文献
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设计并合成了7种新型甲壳型液晶高分子,研究了液晶基元的化学结构和立体效应对单体及其聚合物液晶性的影响.发现在液晶基元的末端引入极性或可极化的原子基团提高了单体的熔点和液晶相的热稳定性;液晶基元的长径比越大,单体的熔点和清亮点越高;聚合使单体的液晶稳定性增加、液晶相温度范围变宽;侧链液晶基元的极性、刚性和空阻越大,聚合物的玻璃化温度越高;酰胺基团无论是在分子的末端还是在连接部位,都使单体的熔点和聚合物的玻璃化温度提高,但在分子末端时液晶相较稳定,作为中心桥键时不利于液晶相的稳定形成. 相似文献
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Hong Zhang Fengying Hong Dezhao Zhu Zhengce Xia Hongxiang Wu Hui Wang Zhuo Zeng 《中国化学》2015,33(7):771-776
A series of novel tolane‐type liquid crystals with amide group as terminal group have been prepared. The terminal amide groups were modified, and the influence of these structural parameters on liquid crystal phases was investigated by polarizing optical microscope (POM) and differential scanning calorimetry (DSC). Three of these new compounds exhibit nematic phase, good thermal stabilities. In general, these liquid crystals with amide as end groups have high melting points and phase transition temperatures, which result from the hydrogen bonds. Based on theoretical calculations, these new molecules with strong electron donating amide as end group have narrower HOMO‐LUMO energy gap and higher dipole moment than tolane. 相似文献
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The phase transition curves of a multi-component TN liquid crystal mixture (TN 88-1) and a multi-component cholesteric liquid
crystal mixture (Ch 88-2) were plotted by using a differential scanning calorimeter. The phase transition temperature and
phase transition heat were obtained from the DSC curves. The results show that the components of TN 88-1 are compatible and
they can form a stable mixture with CB 15 chiral liquid crystal. The components of Ch 88-2 are not compatible and Poly (MMA-BMA)
can greatly improve their compatibility.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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J. D. Sudha 《Journal of polymer science. Part A, Polymer chemistry》2000,38(13):2469-2486
Fifteen highly regular hydrogen‐bonded, novel thermotropic, aromatic‐aliphatic poly(ester–amide)s (PEAs) were synthesized from aliphatic amido diols by melt polycondensation with dimethyl terephthalate and solution polycondensation with terephthaloyl chloride. Intermolecular hydrogen bonds more or less perpendicular to the main‐chain direction induce the formation and stabilization of liquid crystalline property for these PEAs. The structure of these polymers, even in the mesomorphic phase is dominated by hydrogen bonds between the amide–amide and amide–ester groups in adjacent chains. Aliphatic amido diols were synthesized by the aminolysis of γ‐butyrolactone, δ‐valerolactone and ε‐caprolactone with aliphatic diamines containing a number of methylene groups from two to six in isopropanol medium at room temperature. Effects of polarity of the solvent on solution polymerization and effect of catalyst on trans esterification were studied. These polymers were characterized by elemental analysis, FTIR, 1H NMR, 13C NMR, solubility studies, inherent viscosity, DSC, X‐ray diffraction, polarized light microscopy, and TGA. All the melt/solution polycondensed PEAs showed multiple‐phase transitions on heating with second transitions identified as nematic/smectic/spherullitic texture. The mesomorphic properties were studied as a function of their chemical structure by changing alternatively m or n. Odd‐even effect on mesophase transition temperature, isotropization temperature, and crystallinity were studied. The effect of molecular weight and polydispersity on mesophase/isotropization temperature and thermal stability were investigated. It was observed that there exists a competition for crystallinity and liquid crystallinity in these PEAs © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2469–2486, 2000 相似文献
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The synthesis and property of a new series of "mesogen-jacketed liquid crystal polymers" are reported. These polymers have aromatic amide structures as the mesogenic groups and are represented by poly-2,5-bis(4-methoxy- benzamido)styrene. The preliminary study on properties shows that the polymers have very high glass transition temperatures as well as very low critical concentrations for the formation of the lyotropic liquid crystal phase. The results indicate a high degree of chain rigidity. However, the liquid crystalline order of molecular organization in bulk samples disappears upon heating to the glass transition temperature as revealed by polarizing microscopy and by X-ray diffractometer. Therefore, the liquid crystalline order of these polymers forms only through solution but not through heating. This behavior is different from that of the previously studied poly-2,5-bis[(4-methoxybenzoyl)oxy]styrene and its homologs. The latter polymers are liquid crystals both lyotropically and thermotropically. © 1997 John Wiley & Sons, Ltd. 相似文献
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Garidel P 《Physical chemistry chemical physics : PCCP》2006,8(19):2265-2275
The thermotropic phase behaviour and structural organisation of ceramide N-linoeoyl-phytosphingosine (ceramide 3A) is investigated by means of differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Its polymorphism and structural properties are compared with two ceramides of the type III class with various hydrocarbon chain saturation degrees. After hydration the main phase transition temperature of ceramide 3A is found at 76 degrees C with a phase transition enthalpy of +29 kJ mol(-1). Analysing the frequency of methylene stretching vibrations (by infrared spectroscopy) reveals that the fluidity (amount of trans-gauche isomers) is strongly increased for ceramide 3A compared to its stearoyl ceramide type III analogue. After lipid hydration, the acyl chains of all investigated phytosphingosine ceramides of type III adopt a hexagonal-like chain packing. The amide I and amide II vibrations are quite sensitive to the phase transition of the ceramide. The corresponding band analysis reveals strong inter- and intramolecular hydrogen bonds between the amide and hydroxyl groups in the ceramide head groups. The H-bonding network and conformation of the head group of ceramide 3A is only slightly influenced by hydration. The water penetration capacity of ceramide 3A is, however, considerably larger compared to other phytosphingosine derivatives. The structural and organisational properties of ceramides of type III class are discussed with respect to their physiological relevancies for the stratum corneum lipid barrier property of the skin. 相似文献
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Ory Ramon Ellina Kesselman Ronen Berkovici Yachin Cohen Yaron Paz 《Journal of Polymer Science.Polymer Physics》2001,39(14):1665-1677
Temperature‐induced phase separation of poly(N‐isopropylacrylamide) in aqueous solutions was studied by attenuated total reflectance (ATR)/Fourier transform infrared spectroscopy. The main objectives of the study were to understand, on a molecular level, the role of hydrogen bonding and hydrophobic effects below and above the phase‐separation temperature and to derive the scenario leading to this process. Understanding the behavior of this particular system could be quite relevant to many biological phenomena, such as protein denaturation. The temperature‐induced phase transition was easily detected by the ATR method. A sharp increase in the peaks of both hydrophobic and hydrophilic groups of the polymer and a decrease in the water‐related signals could be explained in terms of the formation of a polymer‐enriched film near the ATR crystal. Deconvolution of the amide I and amide II peaks and the O? H stretch envelope of water revealed that the phase‐separation scenario could be divided, below the phase‐separation temperature, into two steps. The first step consisted of the breaking of intermolecular hydrogen bonds between the amide groups of the polymer and the solvent and the formation of free amide groups, and the second step consisted of an increase in intramolecular hydrogen bonding, which induced a coil–globule transition. No changes in the hydrophobic signals below the separation temperature could be observed, suggesting that hydrophobic interactions played a dominant role during the aggregation of the collapsed chains but not before. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1665–1677, 2001 相似文献