TITLE

Nematic wetting at the free surface of 4-cyano-4′-n-alkyl-biphenyls

AUTHOR(S)
Kasten, H.; Strobl, G.
PUB. DATE
October 1995
SOURCE
Journal of Chemical Physics;10/15/1995, Vol. 103 Issue 15, p6768
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
The free surface of a homologous series of low molecular weight liquid crystals 4-cyano-4′-n-alkyl-biphenyls (nCB, n=5,6,7,8) is studied by reflection ellipsometry. On approaching the bulk isotropic–nematic transition temperature TNI from the isotropic phase, the growth of a nematic layer at the surface is observed. The director orientation in the layer is identified as homeotropic. The ellipsometric data are analyzed in terms of a perturbation calculation. It is shown that for 7CB and 8CB very close to TNI, where the layer has a thickness d≥50 Å, both d and the order parameter S0 at the surface can be determined. In all other cases only one parameter, which corresponds to the nematic coverage, can be extracted from the data. Results are discussed in terms of a wetting process. Partial wetting by the nematic phase is observed for n=6,7,8. On approaching TNI from lower temperatures where the bulk is in the nematic phase a small increase of excess surface order is measured which is interpreted as a homeotropic nematic wetting layer possessing higher order than the nematic bulk. © 1995 American Institute of Physics.
ACCESSION #
7649460

 

Related Articles

  • Fast write and erase surface resistance induced nematic liquid crystal display. Monkade, M.; Fuliang, Zang; Martinot-Lagarde, P.; Durand, G. // Applied Physics Letters;3/30/1987, Vol. 50 Issue 13, p856 

    A room-temperature nematic liquid crystal cell is prepared in the homeotropic geometry using dielectrically positive pentyl cyanobiphenyl. The indium tin oxide electrodes are treated to increase locally their surface resistance. At high frequencies (ω>ωc) the border of these regions...

  • X-ray Structure Analysis of 4-Cyano-4'-n-Undecyloxybiphenyl. Rajnikant; Gupta, V. K.; Dinesh; Kumar, A.; Varghese, B. // Crystallography Reports;Mar2003, Vol. 48 Issue 2, p286 

    The structure of a liquid crystal of 4-cyano-4'-n-undecyloxybiphenyl (C[sub 24]H[sub 31]NO) is determined by X-ray diffraction. The compound crystallizes in the monoclinic crystal system (space group C2/c) with the unit cell parameters a = 84.108(7) �, b = 7.159(2) �, c = 6.922(2)...

  • Permittivity of Liquid Crystals of the Alkylcyanobiphenyl Group in a Decimeter Wavelength Range. Belyaev, B. A.; Drokin, N. A.; Shabanov, V. F.; Shepov, V. N. // Physics of the Solid State;May2000, Vol. 42 Issue 5, p987 

    The high-frequency dielectric spectra of liquid crystals of the alkylcyanobiphenyl group with various length of the mobile alkyl chain C[sub n]H[sub 2n + 1] (n = 5-8) are experimentally studied. It is established that a resonance feature is observed in the frequency range of 300 MHz for all the...

  • Room-temperature diphenyl-diacetylene liquid crystals. Shin-Tson Wu; Margerum, J.D. // Applied Physics Letters;8/10/1992, Vol. 61 Issue 6, p630 

    Examines synthesis on asymmetric diphenyl-diacetylene liquid-crystal compounds and characterization of physical properties. Use of compounds as excellent host candidates for eutectic mixtures; Addition of polar diphenyl-diacetylene for enhancement of dielectric anisotropy; Significance of...

  • Effect of CdSe/ZnS semiconductor quantum dots on the dynamic properties of nematic liquid-crystalline medium. Shurpo, N. A.; Vakshtein, M. S.; Kamanina, N. V. // Technical Physics Letters;Apr2010, Vol. 36 Issue 4, p319 

    Issues pertaining to the effect of quantum dots (QDs) on the properties of a nematic liquid-crystalline mesophase are briefly considered. The influence of nanoobjects representing CdSe/ZnS semiconductor QDs on the temporal characteristics of liquid crystals (LCs) belonging to the class of...

  • Detection of phase transitions in liquid crystals on a water surface by a Maxwell displacement current-measuring technique. Iwamoto, Mitsumasa; Kubota, Tohru; Muhamad, Muhamad Rasat // Journal of Chemical Physics;6/15/1995, Vol. 102 Issue 23, p9368 

    The phase transitions of Langmuir films of liquid-crystal 4-cyano-4’-5-alkyl-biphenyl (5CB), 4-cyano-4’-7-alkyl-biphenyl (7CB), 4-cyano-4’-8-alkyl-biphenyl (8CB), and 4-cyano-4’-10- alkyl-biphenyl (10CB) were investigated by a Maxwell displacement current...

  • Å»ywice i sieci epoksydowe o wÅ‚aÅ›ciwoÅ›ciach anizotropowych. Mossety-Leszczak, Beata; Galina, Henryk; Włodarska, Magdalena; Kowalik, Marcin; Łokaj, Krzysztof; Florjańczyk, Zbigniew // Polimery;2009, Vol. 54 Issue 10, p719 

    A general characteristics of liquid crystalline polymer systems, especially epoxy ones, is given on the basis of literature. Own research was focused on the synthesis of liquid crystalline diepoxy monomer (LCM, Scheme A) in which a tetracyclic aromatic diester of biphenyl-4,4′-diol was a...

  • Structure and molecular ordering extracted from residual dipolar couplings: A molecular dynamics simulation study. Stevensson, Baltzar; Komolkin, Andrei V.; Sandstro¨m, Dick; Maliniak, Arnold // Journal of Chemical Physics;2/1/2001, Vol. 114 Issue 5 

    A molecular dynamics (MD) simulation, based on a realistic atom-atom interaction potential, was performed on 4-n-pentyl-4[sup ′]-cyanobiphenyl (5CB) in the nematic phase. The analysis of the trajectory was focused on the determination of molecular structure and orientational ordering using...

  • Dielectric Properties of Liquid Crystals of the Cyano Derivative Compounds with Different Fragments in the Molecular Core. Belyaev, B.A.; Drokin, N.A.; Shabanov, V.F.; Baranova, V.A. // Physics of the Solid State;Mar2004, Vol. 46 Issue 3, p574 

    This paper reports on the results of investigations into the influence of variations in the chemical composition of the aromatic core of cyano-containing molecules of liquid crystals on their dielectric properties in the frequency range 1–2000 MHz. It is shown that the dispersion of the...

Share

Read the Article

Courtesy of VIRGINIA BEACH PUBLIC LIBRARY AND SYSTEM

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics