共查询到20条相似文献,搜索用时 15 毫秒
1.
A series of new side-chain liquid crystalline polymers containing chenodiol residue derived from 24-[4′-hydroxybiphenyl-4-yl-4-(allyloxy)benzoyloxy]-3α,7α-di{n-[4′-(4-ethoxybenzoyloxy)biphenyl-4-yloxy]-n-oxoalkanoyloxy}-5β-cholane was designed and prepared. The chemical structures of the monomer and polymer were confirmed by Fourier transform
infrared and 1H NMR spectra. The mesomorphic properties of monomer and polymer were investigated by differential scanning calorimetry, thermogravimetric
analysis, polarizing optical microscopy, and X-ray diffraction. The side-chain liquid crystalline polymers revealed wide mesophase
temperature range and high thermal stability, and they showed nematic liquid crystalline phase. The influence of flexible
space group length on thermal properties and specific rotation was examined. 相似文献
2.
A new series of sulfur-containing side-chain liquid crystalline polymer is described. Mesomorphic side chains with methylene spacers of different lengths have been synthesized, and their structures were identified by nuclear magnetic resonance, infrared and mass spectrometry. The liquid crystalline nature of the polymers was characterized by microscopy and differential scanning calorimetry. 相似文献
3.
4.
利用紫外-可见光谱,对比研究了尾挂侧链液晶聚合物和腰挂侧链液晶聚合物在结晶相和液晶相转变过程中的液晶基元取向情况.研究表明,石英基材表面倾向于诱导偶氮液晶基元垂直于基材排列;观察到了在液晶态尾挂侧链液晶聚合物和腰挂侧链液晶聚合物的不同取向行为.在室温下重新结晶数天后,腰挂液晶聚合物的紫外可见光谱缓慢回复. 相似文献
5.
Lu Yin Li Han Feijie Ge Xia Tong Wei Zhang Armand Soldera Yue Zhao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(35):15241-15246
Liquid crystalline elastomers (LCEs) have been actively investigated as stimuli-controlled actuators and soft robots. The basis of these applications is the ability of LCEs to undergo a reversible shape change upon a liquid crystalline (LC)-isotropic phase transition. Herein, we report the synthesis of a novel LCE based on a side-chain liquid crystalline polymer (SCLCP). In contrast to known LCEs, this LCE exhibits a striking anomalous shape change. Subjecting a mechanically stretched monodomain strip to LC-disorder phase transition, both the length and width of the strip contract in isotropic phase, and both elongate in LC phase. This thermally induced behaviour is the result of a subtle interplay between the relaxation of polymer main chain oriented along the stretching direction and the disordering of side-group mesogens oriented perpendicularly to the stretching direction. This finding points out potential design of LCEs of this peculiar type and possible applications to exploit. 相似文献
6.
7.
The conformation of the main-chain (backbone) of a combined main-chain/side-chain liquid crystalline polymer has been qualitatively determined by small angle neutron scattering in the oriented nematic, the smectic A and the smectic C phases. The polymer backbone presents only a weak anisotropy, of prolate shape, in the nematic and the smectic C phases. A stronger reorientation of the backbones in the direction of the applied magnetic field is measured for the SA phase. However, this anisotropy remains small compared to the stretching of a main-chain liquid crystal polymer and the smectic structure results apparently from side-chain ordering. On the other hand, hydrodynamic measurements show that the combined polymer, in solvent, is as flexible as a polystyrene chain. This result is compatible with an explanation for the weak observed anisotropy. 相似文献
8.
合成了偶氮苯侧链液晶聚合物聚甲基丙烯酸(3-[4-(4′-氰基偶氮苯)苯氧基]丙酯)(PM3ABCN),采用原位掠入射X射线衍射(GIXRD)方法研究了该聚合物膜在向列相和各向同性态(无定形相)时对气体的阻隔特性.并采用X射线能谱仪(EDS)分析铁片氧化后的氧含量,计算得到渗透通过聚合物膜的氧气的量.结果表明,当PM3ABCN膜处于各向同性态时,通过聚合物膜的氧气平均渗透量为1.92×10-3cm3 day-1m-2;而处于液晶态的膜对氧气的阻隔性提高了4.4倍,氧气平均渗透量为4.38×10-4 cm3day-1 m-2.结合样品表面的显微分析结果,探讨了液晶凝聚相结构对气体小分子的阻隔机理. 相似文献
9.
In this work we have used synchrotron x-radiation diffraction to follow in real-time the isotropic-smoetic phase transition of a side-chain liquid crystalline polymer. The analysis of the x-ray data indicated that the transition occurs within a very narrow biphasic region. As the transition takes place, the size of the smectic regions, as indicated by the width of the diffraction peaks, changed only very slightly before impingement, suggesting a two-dimensional growth pattern. A thermal investigation of the polymer paralleling the x-ray experiments was undertaken and a kinetic analysis applied to the resulting data. Qualitative agreement with a disk-like growth of the smectic regions was found. We have shown that the overall kinetics of the isotropic-smectic transition of a side-chain polymer can be studied by x-ray diffraction permitting the evaluation of several structural parameters. © 1993 John Wiley & Sons, Inc. 相似文献
10.
《Supramolecular Science》1994,1(1):21-32
A new methodology is described, based on the Baylis-Hillman reaction, by which thermally stable side-chain liquid crystal (SCLC) polymers can be prepared incorporating a variety of functional groups along the polymer backbone. This methodology also allows a polar group, especially hydroxyl, to be inserted adjacent to the point of attachment of the spacer group to the polymer backbone. The spatial arrangement of the hydroxyl and functional groups is not only conducive to the formation of liquid crystalline phases but may also influence the tacticity of the polymer backbone. 相似文献
11.
Aaron Moment Ruben Miranda Paula T. Hammond 《Macromolecular rapid communications》1998,19(11):573-579
The synthesis of a new liquid crystalline block copolymer consisting of a polystyrene block and a side-chain liquid crystalline siloxane block is reported. The synthetic approach described is based on the anionic polymerization of styrene and cyclic trimethyltrivinyltrisiloxane monomers, followed by functionalization of the siloxane block with side chain mesogens. The siloxane block has a Tg well below 25°C and is designed to exhibit a chiral smectic C* phase at room temperature. These block copolymers are the first side-chain liquid crystalline block copolymers which contain both a high Tg glassy block and a low Tg liquid crystalline block. 相似文献
12.
A series of novel multi-arm star side-chain liquid crystalline (LC) copolymers with hyperbranched core moieties were synthesized by atom transfer radical polymerization (ATRP) using a multi-functional hyperbranched polyether as the initiator and chlorobenzene as the solvent. The multi-functional hyperbranched polyether initiator was prepared from poly(3-ethyl-3-(hydroxymethyl)oxetane) (PEHO) and 2-bromo-2-methylpropionyl bromide. The azobenzene side-chain liquid crystalline arms were designed to have an LC conformation of poly[6-(4-methoxy-4′-oxy-azobenzene)hexyl methacrylate] with different molecular weights. Their characterization was performed with 1H NMR, size exclusion chromatograph (SEC), differential scanning calorimetry (DSC) and thermal polarized optical microscopy (POM). The multi-arm star side-chain liquid crystalline copolymers exhibited a smectic and a nematic phase, and the phase transition temperatures from the smectic to the nematic phase and from the nematic to isotropic phase increased with increasing the molecular weight of the multi-arm star side-chain liquid crystalline copolymers from 1.78 × 104 to 9.07 × 104. 相似文献
13.
14.
Matsuyama A 《The Journal of chemical physics》2007,127(8):084906
We present a mean field theory to describe volume phase transitions of side-chain liquid crystalline gels. Three different uniaxial nematic phases (N(1), N(2), and N(3)) are defined by using orientational order parameter S(m) of side-chain liquid crystals (mesogens) and S(b) of backbone chains. We derive the free energy for the three nematic phases of side-chain liquid crystalline gels dissolved in isotropic solvents and calculate the swelling curve of the gel, the order parameters of a backbone chain and of side-chain liquid crystals, and the deformation of the gel as a function of temperature and an electric field. We find isotropic-nematic (N(1), N(2), and N(3)) and N(1)N(2) phase transitions of the gels, depending on the interaction between a backbone chain and a side-chain liquid crystal. 相似文献
15.
Chang-Jyh Hsieh Chain-Shu Hsu Ging-Ho Hsiue Virgil Percec 《Journal of polymer science. Part A, Polymer chemistry》1990,28(2):425-435
The synthesis of side-chain liquid crystalline polysiloxanes containing oligooxyethylene spacers and 4-methoxyphenyl benzyl ether and 6-cyano-2-naphthyl benzyl ether based mesogenic groups is presented. The phase behavior of both monomeric and polymeric liquid crystals was characterized by differential scanning calorimetry and optical polarized microscopy. All synthesized polysiloxanes present smectic mesomorphism. The insertion of oxygen atoms into the flexible aliphatic spacers leads to decrease in both glass transition and isotropization temperatures of the resulting side-chain liquid crystalline polymers. 相似文献
16.
Joaquim J. Moura Ramos Joo F. Mano David Lacey G. Nestor 《Journal of Polymer Science.Polymer Physics》1996,34(12):2067-2075
The molecular relaxation mechanisms in the glass transition region and in the liquid crystalline phase exhibited by two side-chain liquid crystalline polysiloxanes have been studied by Thermally Stimulated Discharge Currents. These results were compared with those previously obtained by dielectric relaxation spectroscopy. It was observed that two relaxation mechanisms were present in the liquid crystalline phase, and we suggest that these might correspond to the motions of the mesogenic moieties in the liquid crystalline phase. © 1996 John Wiley & Sons, Inc. 相似文献
17.
一种西佛碱侧链型液晶高分子的合成及表征 总被引:2,自引:0,他引:2
一种西佛碱侧链型液晶高分子的合成及表征邹友思,林国良,姚青青,戴李宗,潘容华(厦门大学化学系厦门361005)关键词联苯,西佛碱,侧链型,液晶高分子,基团转移聚合Finkellnann等提出的柔性基去偶合概念’]已在侧链型液晶高分子的研究中得到了证实... 相似文献
18.
Zhang S Terentjev EM Donald AM 《Langmuir : the ACS journal of surfaces and colloids》2005,21(8):3539-3543
Atomic force microscopy (AFM) is employed to study the supermolecular microstructures of disclinations and inversion walls in thin films of a smectic side-chain liquid crystalline polymer. Two-dimensional nanostripes are formed in thin films when the material enters the smectic phase. A possible mechanism for their formation is also suggested. The stripes run parallel to the local director and thus decorate the overall patterns of nematic director around the disclinations and inversion walls. Three patterns involving radial, spiral, and circular supermolecular microstructures of a positive disclination with s = +1 and one hyperbolic pattern of a negative disclination with s = -1 are observed. The cores of all these microstructures exhibit circular dark centers in AFM height images. It is found that the specific configurations of a pair of (+1, -1) disclinations form during the late stage of annihilation and inversion walls always separate a pair of (+1, +1) disclinations. The analysis on the director fields around disclinations and inversion walls shows that the bend and splay elastic constants are of the same order of magnitude in the side-chain liquid crystalline polymer. 相似文献
19.
Alan William Hall David Lacey Gary Stevenson 《Macromolecular rapid communications》1998,19(3):139-144
We have investigated the use of the Wittig-Horner reaction in the preparation of novel side-chain liquid crystalline (SCLC) polymers. The simplicity and versatility of the Wittig-Horner methodology makes it another useful synthetic route in preparing SCLC polymers with polar groups being positioned along the polymer backbone. This new methodology will now be used to synthesise a range of novel ferroelectric SCLC polymers. 相似文献