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Synthesis of novel aromatic polyimides containing bulky side chain for vertical alignment liquid crystals

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Chinese Chemical Letters 2008年第3期19卷 359-362页

作者： Jian Wang Ying Han Wang State Key Laboratory of Polymer Materials Engineering of China College of Polymer Science and Engineering Sichuan University Chengdu 610065 China

In this study, a novel 4-（4-octyloxybenzoyloxy）biphenyl-3′,5′-diaminobenzoate and polyimides based on it were synthesized. The polyimide with mesogenic unit side chain exhibited excellent vertical alignment for nematic liquid crystal （LC）. The pretilt angles of LCs above 89° were kept after the rubbing process with 220 mm rubbing strength. The polyimide films as the alignment layer were baked at 120℃ for 12 h, the vertical alignment of LCs was still uniform and stable. Meanwhile, the UV-vis spectra of the noyel polyimide films showed the high transparency in a visible wave length.

关键词： Polyimide liquid crystal Vertical alignment

A tensor model for liquid crystals on a spherical surface

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Science China Mathematics 2013年第12期56卷 2549-2559页

作者： CHENG Hong ZHANG PingWen School of Mathematical Sciences Peking University

Rod-like molecules confined on a spherical surface can organize themselves into nematic liquid crystal phases. This can give rise to novel textures displayed on the surface, which has been observed in experiments. An important theoretical question is how to find and predict these textures. Mathematically, a stable configuration of the nematic fluid corresponds to a local minimum in the free energy landscape. By applying Taylor expansion and Bingham approximation to a general molecular model, we obtain a closed-form tensor model, which gives a free energy form that is different from the classic Landau-de Gennes model. Based on the tensor model, we implement an efficient numerical algorithm to locate the local minimum of the free energy. Our model successfully predicts the splay, tennis-ball and rectangle textures. Among them, the tennis-ball configuration has the lowest free energy.

关键词： liquid crystal nematic texture Bingham closure approximation tennis-ball configuration

Activities of liquid crystals in Acupuncture Points

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Wuhan University Journal of Natural Sciences 1998年第3期3卷 112-114页

作者： Ma, Wentao Liu, Shaoan Liu, Nai Hu, Jiming Cao, Lianxin Wuhan University Center of Analysis and Measurement Wuhan China (GRID:grid.49470.3e) (ISNI:***) the Third Wuhan Municipal Hospital Section of Acupuncture and Moxibustion Wuhan China (GRID:grid.49470.3e)

The theory of Meridians is an important part of Traditional Chinese Medicine. Modern science should play its role in analysing and making clear the mystique of the theory. The relation between the activities of liquid crystals in acupuncture points and the regulative actions of Meridians was studied in this paper. The results showed the intimate intrinsic association between them.

关键词： liquid crystal acupuncture point meridian

Forming of A New liquid crystalline through Hydrogen Bonding

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Wuhan University Journal of Natural Sciences 1998年第2期3卷 209-213页

作者： Hu Yangjian, Huang Ronghua, Zhang Xianliang’(College of Chemistry, Wuhan University,Wuhan 430072,China) Wuhan University College of Chemistry Wuhan China (GRID:grid.49470.3e) (ISNI:***)

A stable Sc phase is formed through hydrogen bonding between side-chain aromatic acid groups of polysiloxane: Bending of polysiloxane with N-Acetyl Latimic acid (NAA) gives a chiral S c * phase; The influence of polymerism and hydrogen bond induction effect over mesophase is discussed. The influence of NAA over mesophase is studied.

关键词： hydrogen bond induction effect liquid crystal polysiloxane

Syntheses and Characterization of New Chiral Side-Chain liquid crystalline Polysiloxanes

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Wuhan University Journal of Natural Sciences 1998年第2期3卷 253-254页

作者： Tang Hongding Xu Guangwei Zhang Xianliang Wuhan University College of Chemistry Wuhan China (GRID:grid.49470.3e) (ISNI:***)

A new serial chiral side-chain liquid crystal polysiloxanes containing L-Tyr structures were synthesized at room temperature. Both of them exhibited Sc phase at room temperature.

关键词： polysiloxanes liquid crystal L-Tyrosine

Lyotropic liquid crystals of tetradecyldimethylaminoxide in water and the in situ formation of gold nanomaterials

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ChemPhysMater 2023年第2期2卷 134-140页

作者： Na Zhang Aoxue Xu Baoyong Liu Nicolas Godbert Hongguang Li Key Laboratory of Colloid and Interface Chemistry Ministry of EducationSchool of Chemistry and Chemical EngineeringShandong UniversityJinan 250100 China b College of Pharmacy Binzhou Medical UniversityYantai 264003 China c School of Chemistry and Chemical Engineering Lanzhou Jiaotong UniversityLanzhou 730070 China d MAT_INLAB(Laboratorio di Materiali Molecolari Inorganici) Centro di Eccelenza CEMIF.CALLASCAMM CR-INSTM Della CalabriaDipartimento di Chimica e Tecnologie ChimicheUniversitàdella CalabriaArcavacata di(CS)Rende 87036Italy

Lyotropic liquid crystals(LLCs)produced by the self-assembly of surfactant in water represent an important class of highly ordered soft materials that have a wide range of *** study investigates the LLCs formed by a zwitterionic surfactant(tetradecyldimethylaminoxide,C 14 DMAO)in *** organization of C 14 DMAO within the LLCs was determined based on a detailed analysis of small-angle X-ray scattering measure-ments and polarized microscopy observations of a typical *** to the singe-phase region,which has a hexagonal organization,several two-phase regions were observed,exhibiting the coexistence of hexago-nal/cubic,cubic/lamellar,and hexagonal/lamellar *** phase behavior showed an obvious dependence on temperature,with more pronounced two-phase regions at lower *** the LLCs as a matrix,Au nanospheres,nanoellipsoids,and nanorods were prepared without requiring additional reducing *** three-and one-dimensional Au nanomaterials could be converted to two-dimensional plates via the introduc-tion of a small amount of cationic surfactant to the LLCs,such as cetyltrimethylammonium bromide(CTAB)and 1-hexadecyl-3-methylimidazolium bromide([C 16 MIm]B),which showed pronounced surface-enhanced Raman scattering activity towards solid *** LLCs loaded with CTAB(or[C 16 MIm]B)and HAuCl 4 exhibited slightly different structures and mechanical strength from the original LLCs,thereby forming a new class of highly crowded colloidal materials.

关键词： Surfactant Lyotropic liquid crystal Gold nanoplate Surface-enhanced Raman scattering

Dielectric study of three homologous Schiff base ferroelectric liquid crystals with the variations of temperature and frequency

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Journal of Advanced Dielectrics 2020年第5期10卷 11-24页

作者： Vijayshree Patil N. B.N.Veerabhadraswamy Susanta Chakraborty S.M.Khened R.D.Mathad C.V.Yelamaggad Department of Physics Gulbarga University Kalaburagi 585106KarnatakaIndia Centre for Nano and Soft Matter Sciences Prof.U.R.Rao Road Jalahalli Bengaluru 560013KarnatakaIndia Department of Physics Laxmi Venkatesh Desai College Raichur 584101KarnatakaIndia Department of Physics North Bengal UniversitySiliguri Darjeeling 734013West BengalIndia

In this investigation,the dielectric behaviors of three ferroelectric liquid crystals(FLCs)belonging to a homologous series have been revealed in the frequency range of 10 Hz-10 *** used in this study are three-ring calamitic LCs,namely(S)-4-(((4-(octan-2-yloxy)phenyl)imino)methyl)phenyl 4-(n-octyloxy)benzoate,(S)-4-(((4-(octan-2-yloxy)phenyl)imino)methyl)phenyl 4-(n-decyloxy)benzoate and(S)-4-(((4-(octan-2-yloxy)phenyl)imino)methyl)phenyl 4-(n-undecyloxy)*** polarizing optical microscopic and differential scanning calorimetric results confirm that these compounds,synthesized as per the known synthetic steps,show not only a ferroelectrically switchable chiral smectic C(SmC*)phase over a wide thermal range,but also other mesophases such as blue phase-I/II(BP-I/II),chiral nematic(N*)and unknown smectic(SmX)*** essential dielectric parameters of the FLC phase have been measured at different *** relative permittivity has been measured with the variations of temperature and ***,the dielectric loss and tanδhave been *** dielectric relaxations have been calculated and explained at the molecular *** systematic measurements revealed a strong anomaly,and crossover of relative permittivity values for the FLCs has been determined at selective frequencies between 1 kHz and 20 *** dielectric anomaly/fall for the response function infers the involvement of collective response of dipolar assembly confined to ferroelectric Weiss domains.

关键词： liquid crystal tanδ relative permittivity Maxwell-Wagner mode Goldstone mode smectic C*phase

ADVANCES IN liquid crystalLINE POLYESTERS

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Chinese Journal of Polymer Science 1992年第3期10卷 195-202页

作者： W. J. Jackson Jr. Research Laboratories Eastman Chemical Company Eastman Kodak Company Kingsport Tennessee U.S.A.Research Laboratories Eastman Chemical Company Eastman Kodak Company Kingsport Tennessee U.S.A.

Advances have been made in understanding the interactions of composition, molecular weight, liquid crystallinity,orientation, and three-dimensional crystallinity on the properties of injection-molded and melt-spun liquid crystalline polyesters (LCP's). Two classes of potentially low-cost LCP's were compared:(1) semiflexible LCP's prepared from 1,6-hexanediol and the dimethyl ester of either trans-4, 4'stilbenedicarboxylic acid or 4.4 ' biphenyldicarboxylic acid and (2) all-aromatic LCP's prepared from terephthalic acid, 2, 6-naphthalenedicarboxylic acid, the diacetate of hydroquinone, and the acetate of p-hydroxybenzoic acid. The effects of composition on the plastic properties of the 4-component all-aromatic LCP's were determined with the aid of a 3 x 3 factorial statistically designed experiment, the generation of equations with a computer program, and the plotting of three-dimensional figures and contour diagrams. The effects of absolute molecular weight (M_w) on the tensile strengths of the semiflexible LCP's and one of the all-aromatic LCP's having an excellent balance of plastic properties were also compared, and it was observed that the semiflexible LCP's required M_w's about 4 times higher than the all-aromatic LCP to attain a given strength. Persistence lengths and molecular modeling were used to explain these differences.

关键词： liquid crystal thermotropic polyester plastic properties

Photoreaction Behaviors of Two liquid crystalline Cinnamoyl Compounds with Different Phase in Solution and Mesomorphic States

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Chinese Journal of Chemical Physics 2010年第6期23卷 719-725,746页

作者：董晓明郭金宝魏杰北京化工大学材料学院北京100029

A novel nelnatic liquid crystal compound containing a cinnamoyl moiety （PCPC） and a typically cholesteric liquid crystal cholesteryl cinnamate （CC） were synthesized to explore the mechanism ofcinnamoyl compounds, and the chemical structures of photodimerization were confirmed by Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance spectral analysis. The photoreaction behaviors of these two cinnamoyl compounds in mesomorphic state and solution were investigated, UV-Vis spectral analysis was used to analyze the photoproduct. The results show that the photochemistry of PCPC in nematic state involves both photodimerization and photoisomerization, while CC shows a complex reaction which can be divided into three parts, and this has enabled us to present new data and interpretations regarding the [2＋2] photocycloaddition reaction. Additionally, the results of UV-Vis spectral analysis in solutions strongly suggest that UV-Vis spectral analysis can be used to study the kinetic behaviors of cinnamoyl moiety photoreaction.

关键词： Cinnamoyl compound liquid crystal Photoreaction behavior