摘要:

General procedures are described for the synthesis of members of five pairs of related homologous series of mesogenic azomethines differing in the mode of linkage of the CH˭N group and containing a cycloalkyl group in a terminal position.

ISSN:1058-725X    

DOI:10.1080/10587259508034563

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The molecular organisation in a binary mixture of a strongly polar mesogen (5CB) and a weakly-polar mesogen (ME50.5) is investigated using results of X-ray scattering and density studies. Analysis of the intensity distribution of X-ray scattering has yielded results for orientational order parameters in addition to smectic layer spacings and effective molecular lengths. The results are compared with a mean field theory of the smectic phase. Previously unexplained results for mixtures showing a minimum in the anisotropy of physical properties coincident with a maximum in the nematic/smectic A transition entropy are shown to be consistent with the theory. We conclude that favourable packing of molecules in the injected smectic A phase stabilises the layers but increases the orientational free volume, consistent with a lower orientational order parameter.

ISSN:1058-725X    

DOI:10.1080/10587259508034564

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Dielectric measurements on a mixture of a liquid crystalline polysiloxane and a low molecular mass dye as well on the pure polymer have been carried out in the frequency range from 100 Hz to 13 MHz. Three relaxation regimes have been found for the polymer-dye mixture. The shift of relaxation frequencies in the isotropic and nematic phases of the pure polymer was used to calculate the macroscopic order parameter (P2.

ISSN:1058-725X    

DOI:10.1080/10587259508034565

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The synthesis of nickel complexes dibenzotetraaza[14]annulenes bearing four, six or eight long paraffinic chains is described. Preliminary results concerning the mesomorphic properties of such systems show that those compounds exhibit a wide range hexagonal columnar phase.

ISSN:1058-725X    

DOI:10.1080/10587259508034566

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We have proposed a new optical method for measuring the twist angle of twisted nematic cells. The method is applied to estimate the azimuthal anchoring energy of a nematic liquid crystal 5CB aligned on the as-stacked polyimide Langmuir–Blodgett (PI-LB) films. The measured values of the anchoring energies are shown to range from 2 × 10−6J/m2to 1 × 10−5J/m2, which depend on the LB deposition conditions and show the optimum condition for the deposition. The values of the azimuthal anchoring energy are known to be one or two orders of magnitude lower than the corresponding polar anchoring energy.

ISSN:1058-725X    

DOI:10.1080/10587259508034567

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We have synthesized the novel organic-solvent-soluble polyimides having helix backbone structure and containing four different types of diamine with trifluoromethyl groups as alignment films for liquid crystal displays. These alignment films show the pretilt angles of liquid crystal from 2° up to 40°. The surface energies of these polyimide films show a monotonic decrease with the increase of concentration of fluorine atoms in polyimide films. This tendency commonly occurs for four different fluorine containing diamines. A clear relationship between the surface energy of polyimide films and the pretilt angles of liquid crystal on polyimide films was not obtained. The dependence of the obtained pretilt angles on the chemical structure of the polyimides is as follows: the polyimides with fluorine atoms in the lateral benzene rings, which are capable of generating a high pretilt angle of up to 40°, show the linear increasing of pretilt angles with the decreasing of the surface energies. On the other hand, the polyimides with fluorine atoms in polymer backbones show a maximum value of pretilt angles in the medium ranges. These results suggest that the microscopic surface structure of polyimides largely affect the generation of the pretilt angle at the boundary surface between liquid crystals and alignment films.

ISSN:1058-725X    

DOI:10.1080/10587259508034568

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

New chiral dopants containing an optically active six-membered ring with a cyano group were synthesized. New chiral dopants containing an optically active six-membered ring with an epoxy group were also synthesized and the effect of the direction of the dipoles on spontaneous polarization were discussed using them. The spontaneous polarization is thought to be influenced by the direction of the dipoles of the chiral moiety.

ISSN:1058-725X    

DOI:10.1080/10587259508034569

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The atomic distance between shrunken atoms in five representative organic charge-transfer superconductors, (TMTSF)2CIO4,β-(BEDT-TTF)2I3,β-(BEDT-TTF)2IBr2,K-(BEDT-TTF)2Cu[N(CN)2](NCS)2and K3C60were calculated and the shrunken atoms were related to Tcin comparison with inorganic superconductors. The main role of charge transfer force between the cation stack and the insulating layers of anion in the organic superconductors is a compression of the spherical inner paired electron clouds toward to the nucleus, the so-calledpintcheffect. Tcincreases as the pintch effect increases. The electron pair set, 3d10and 2p6, derived from the compressed atoms, Se and S, respectively, in organic superconductors can be explained as an origin of superelectrons, as well as superconducting inorganic compounds and elements.

ISSN:1058-725X    

DOI:10.1080/10587259508034570

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A new method was developed for the preparation of Langmuir-Blodgett (LB) films of oxotitanium phthalocyanine (TiOPc)/copper tetrakis(hexyloxycarbonyl)phthalocyanine (C6CuPc) mixtures, based on the finding that almost insoluble TiOPc becomes soluble in chloroform upon mixing with C6CuPc. Surface pressure-area isotherms of the mixed phthalocyanines suggested that the two phthalocyanines are miscible in the monolayers. Visible absorption spectra and photoconductive properties of the mixed LB films were studied.

ISSN:1058-725X    

DOI:10.1080/10587259508034571

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The 4-pentylphenyl-4′-pentoxythiobenzoate (5S5), C23H30O2S, crystallizes in the monoclinic system: space group P21/c, a = 19.817 (2) Å, b = 5.585 (1) Å, c = 20.238 (2) Å,β∼ 104.792 (8)°, z = 4. The structure was solved by direct methods and refined to the final R = 0.065, for 3415 observed reflections. The pentoxythiobezoate moiety is nearly planer. Molecular rows form an interclated structure. C‒H…O type short intermolecular contacts were found.

ISSN:1058-725X    

DOI:10.1080/10587259508034572

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor