Advertisement

A New Method for Inducing Homeotropic and Tilted Alignments of Nematic Liquid Crystals on Silica Surfaces

  • Leroy J. Miller
  • Jan Grinberg
  • Gary D. Myer
  • Deborah S. Smythe
  • Willis H. Smith
Chapter

Abstract

Homeotropic alignment of a nematic liquid crystal on a silica surface can be induced by means of a prior treatment of the surface with a long-chain aliphatic alcohol or a mixture of such an alcohol and an amine. The treatment is presumed to replace some or all of the hydroxy groups normally attached to silicon atoms at the surface with alkoxy groups derived from the alcohol, thereby reducing the critical surface tension of the surface. As the chain length of the alcohol is decreased, the director of the nematic tilts away from the perpendicular orientation. The direction of tilt can be controlled by shallow angle ion beam etching the silica surface prior to the alcohol treatment, in which case the nematic molecules are uniformly tilted toward the ion beam source. The tilt angle is a function of both the length of the alcohol chain and the composition of the liquid crystal. Tilted homeotropic alignment is essential for obtaining optimum performance of field effect devices that use nematics with a negative dielectric anisotropy.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    (a) F.J. Kahn, G.N. Taylor, and H. Schonhorn, Proc. IEEE 61, 823 (1973); (b) I. Haller and H.A. Huggins, U.S. Pat. 3,656,834, April 18, 1972; J.E. Goldmacher and M.G. Tayag, U.S. Pat. 3,809,456, May 7, 1974; G.W. Smith and D.B. Hayden U.S. Pat. 3,848,966, Nov. 19, 1974; M. Fukai, K. Asai, S. Nagata, H. Tatsuta, and K. M. ri, U.S. Pat. 3,979,319, Sept. 7, 1976.CrossRefGoogle Scholar
  2. 2.
    (a) H. Sorkin and R.I. Klein, U.S. Pat. 3,698,449, Oct. 17, 1972; (b) J.E. Proust, L. Ter-Minassian-Saraga, and E. Guyon Solid State Commun. 11, 1227 (1972); J.E. Proust and L. Ter-Minassian-Saraga, C.R. Acad. Sci. Paris, Ser. C, 276, 1731 (1973); J.E. Proust and L. Ter-Minassian-Saraga, J. Phy Colloq. CI, 36, Cl-77 (1975).Google Scholar
  3. 3.
    (a) F.J. Kahn, Appl. Phys. Lett. 22, 386 (1973); (b) J.C. Dubois, M. Gazard, and A. Zann, Appl. Phys. Lett. 24, 297 (1974); (c) J.C. Dubois, M. Gazard, and A. Zann, J. Appl. Phys. 47, 1270 (1976); (d) I. Haller, Appl. Phys. Lett. 24, 349 (1974); (e) G.J. Sprokel and R.M. Gibson, Electrochemical Soc. Mtg., Las Vegas, Oct. 17–22, 1976, Abst. No. 214.CrossRefGoogle Scholar
  4. 4.
    S. Matsumoto, M. Kawamoto, and N. Kaneko, Appl. Phys. Lett. 27, 268 (1975).CrossRefGoogle Scholar
  5. 5.
    L.T. Creagh and A.R. Kmetz, Mol. Cryst. Liq. Cryst. 24, 59 (1973).CrossRefGoogle Scholar
  6. 6.
    (a) F.J. Kahn, Appl. Phys. Lett. 20, 199 (1972); (b) F.J. Kahn, U.S. Pat. 3,694,053, Sept. 26, 1972; (c) G. Ryschenkow and M. Kiemen, J. Chem. Phys. 64, 404 (1976); M. Klemen and G. Ryschenkow, J. Chem. Phys. 64, 413 (1976); (d) K. Fahrenschon, H. Gruler, and M.F. Schiekel, Appl. Phys. 11, 67 (1976); (e) W. Urbach, M. Boix, and E. Guyon, Appl. Phys. Lett. 25, 479 (1974).CrossRefGoogle Scholar
  7. 7.
    J. Grinberg, W.P. Bleha, A.D. Jacobson, A.M. Lackner, G.D. Myer, L.J. Miller, J.D. Margerum, L.M. Fraas, and D.D. Boswell, IEEE Trans. Elect. Dev. ED-22, 775 (1975).CrossRefGoogle Scholar
  8. 8.
    M.J. Little, H.A. Garvin, and L.J. Miller, Liquid Crystals and Ordered Fluids, J.F. Johnson and R.S. Porter, Eds (Plenum Press, New York, N.Y.), Vol 3, p. 497.Google Scholar
  9. 9.
    H.S. Lim and J.D. Margerum, Appl. Phys. Lett. 28, 478 (1976).CrossRefGoogle Scholar
  10. 10.
    G. Baur, V. Wittwer, and D.W. Berreman, Phys. Lett. 56A, 142 (1976).CrossRefGoogle Scholar
  11. 11.
    V.L. Snoeyink and W.J. Weber, Jr., “Surface Functional Groups on Carbon and Silica,” in Progress in Surface and Membrane Science, ed. by J.F. Danielli, M.D. Rosenberg, D.A. Cadenhead, Vol. 5, Academic Press, New York, 1972, pp. 63–119.Google Scholar
  12. 12.
    R.G. Azrak and C.L. Angell, J. Phys. Chem. 77, 3048 (1973).CrossRefGoogle Scholar
  13. 13.
    We used the alcohols alone only in the case of heptanol and the higher homologues. There is some recent evidence that low boiling alcohols require an amine catalyst when the treatment is carried out at reflux.Google Scholar
  14. 14.
    F.G. Yamagishi, unpublished data.Google Scholar
  15. 15.
    We believe that the surface coverage is more nearly complete with shorter alcohols. This view was supported by ellipsometric measurements made by Prof. Arthur Adamson and Dr. Patrick Hu on quartz surfaces treated with 1-decanol and 1-octadecanol.Google Scholar

Copyright information

© Springer Science+Business Media New York 1978

Authors and Affiliations

  • Leroy J. Miller
    • 1
  • Jan Grinberg
    • 1
  • Gary D. Myer
    • 1
  • Deborah S. Smythe
    • 1
  • Willis H. Smith
    • 1
  1. 1.Hughes Research LaboratoriesMalibuUSA

Personalised recommendations