Crystallography Reports

, Volume 45, Issue 3, pp 501–509 | Cite as

Nematic-isotropic phase transition in polar liquid crystals. 1. Statistical theory

  • A. V. Emel’yanenko
  • M. A. Osipov
Liquid Crystals

Abstract

The theory of transition from the nematic to the isotropic phase for liquid crystals in the system of rodlike particles with large longitudinal dipoles has been developed with due regard for the equilibrium between monomers and antiparallel molecular pairs—dimers. The order parameters of monomers and dimers are determined as well as the dimer fraction. It is shown that, in accordance with the results obtained earlier, for low values of dipole moments, the temperature of the nematic-isotropic phase transition increases with an increase of the dipole moment. However, for large dipoles, the transition temperature starts decreasing with an increase of the dipole moment because of higher dimer concentration. This provides the interpretation of the recent computer simulation, which showed a destabilization of the nematic phase in the system of rigid rods with pronounced central dipoles. The temperature dependence of the dimer fraction is also studied. The qualitative relation between the sign of the jump in the dimer fraction at the transition point and the effect of dimerization on the transition temperature are established.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    P. E. Cladis, Phys. Rev. Lett. 35, 48 (1975).ADSGoogle Scholar
  2. 2.
    F. Hardouin, A. M. Levelut, and G. Sigaud, J. Phys. (Paris) 42, 71 (1981).Google Scholar
  3. 3.
    J. Prost, Adv. Phys. 33, 46 (1984).CrossRefADSGoogle Scholar
  4. 4.
    B. K. Vainshtein and I. G. Chistyakov, in Problems of Modern Crystallography (Nauka, Moscow, 1975), p. 12.Google Scholar
  5. 5.
    W. H. de Jeu, Structural Incommensurability in Crystals, Liquid Crystals, and QuasiCrystals, Ed. by J. F. Scott (Plenum, New York, 1986).Google Scholar
  6. 6.
    G. J. Brownsey and A. J. Leadbetter, Phys. Rev. Lett. 44, 1608 (1980).CrossRefADSGoogle Scholar
  7. 7.
    V. F. Petrov, M. F. Grebenkin, and B. I. Ostrovskii, Kristallografiya 33(5), 1194 (1988) [Sov. Phys.-Crystallogr. 33 (5), 708 (1988)].Google Scholar
  8. 8.
    J. J. Penchev and J. N. Dozov, Mol. Cryst. Liq. Cryst. Sci. Technol., Sect. A 73, 267 (1981).Google Scholar
  9. 9.
    A. Perera and G. N. Patey, J. Chem. Phys. 89, 5861 (1988).ADSGoogle Scholar
  10. 10.
    A. G. Vanakaras and D. J. Photinos, Mol. Phys. 85, 1089 (1995).Google Scholar
  11. 11.
    C. Vega and S. Lago, J. Chem. Phys. 100, 6727 (1994).ADSGoogle Scholar
  12. 12.
    M. A. Osipov and A. Yu. Simonov, Khim. Fiz. 8(7), 992 (1989).Google Scholar
  13. 13.
    S. C. McGrother, A. Gil-Villegas, and G. Jackson, J. Phys. C: Solid State Phys. 8, 9649 (1996).Google Scholar
  14. 14.
    K. Satoh, Sh. Mita, and Sh. Kondo, Liq. Cryst. 20(6), 757 (1996).Google Scholar
  15. 15.
    M. A. Osipov, in Handbook of Liquid Crystals, Ed. by J. Goodby et al. (Wiley, Berlin, 1998).Google Scholar
  16. 16.
    P. C. Jordan, Mol. Phys. 25(4), 961 (1973).Google Scholar
  17. 17.
    A. V. Emel’yanenko and M. A. Osipov, Kristallografiya 45(3), 558 (2000) [Crystallogr. Rep. 45 (3), 510 (2000)].Google Scholar
  18. 18.
    B. W. van der Meer and G. Vertogen, Molecular Physics of Liquid Crystals, Ed. by G. R. Luckhurst and G. W. Gray (Academic, New York, 1979).Google Scholar
  19. 19.
    L. Blum and A. J. Torruella, J. Chem. Phys. 56, 303 (1972).Google Scholar

Copyright information

© MAIK "Nauka/Interperiodica" 2000

Authors and Affiliations

  • A. V. Emel’yanenko
    • 1
  • M. A. Osipov
    • 2
  1. 1.Physics FacultyMoscow State UniversityVorob’evy gory, MoscowRussia
  2. 2.Shubnikov Institute of CrystallographyRussian Academy of SciencesMoscowRussia

Personalised recommendations