Electro-Optic Effects in Liquid Crystal Side Chain Polymers

  • H. J. Coles
  • R. Simon
Chapter
Part of the Polymer Science and Technology book series (POLS, volume 28)

Abstract

The recent work of Krigbaum1 and Blumstein2 on main chain polymer liquid crystals and that of Finkelmann3 and Ringsdorf4 on side chain systems has generated considerable interest in the potential of these materials for use in electro-optic devices. Indeed over the last three years or so papers have started appearing reporting on electro-optic effects in a variety of polymer liquid crystal systems5,6. The main thrust of this initial work has been to examine nematic and cholesteric polymer liquid crystals presumably in the hope of producing electro-optic effects and displays analogous to those observed with monomeric mesophases. However, as observed by Ringsdorf and Zentel6 and Finkelmann et al5, for such polymer materials, the operating parameters are not as convenient as for monomeric systems, i.e. the threshold voltages are higher, the response times are two to ten times slower and the operating temperatures are not usually convenient. Whilst the promise of these new polymer materials would seem to be in combining the polymer specific with the monomeric specific liquid crystal properties the resultant high viscosity associated with the polymer chain would seem to be a major drawback to these systems. The obvious conclusion is therefore that such polymers, in their pure state, will always have inferior performance to equivalent monomers. However as Finkelmann pointed out7 the operating voltages for side chain systems are not impractical and it is possible to use the mesophase to glass transition (at Tg) to store information written electro-optically in the nematic or cholesteric polymer phases. This storage property is fundamental to these polymer liquid crystal materials and appears to be their most important feature. For such a storage device to be useful Tg must be above ambient temperatures. This implies very slow response times (minutes to hours) if the material is heated just above Tg due to the inherent high viscosity of the polymer or very high operating temperatures (~200°C) if response times of less than a second are to be achieved in these nematic or cholesteric polymer liquid crystals. These features would not seem to be desirable for practical storage devices requiring contrast between written and unwritten regions.

Keywords

Anisotropy Epoxy Hull Sine Isopropyl Alcohol 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

Reference

  1. 1.
    W R Krigbaum and H J Lader. Electric field-induced flow instabilities in low molecular weight and polymeric nematics. Mol. Cryst.Liq.Cryst. 62: 87 (1980).CrossRefGoogle Scholar
  2. 2.
    A Blumstein, S Vilasagar, S Ponrathnam, S B Clough and R B Blumstein. Nematic and Cholesteric Thermotropic Polyesters with Azoxybenzene Mesogenic Units and Flexible Spacers in the Main Chain. J.Poly.Sci: Poly.Phys. 20: 877 (1982).ADSCrossRefGoogle Scholar
  3. 3.
    H Finkelmann, H Ringsdorf and J H Wendorff. Model Considerations and examples of Enantiotropic Liquid Crystalline Polymers. Makromol.Chem. 179: 273 (1978).Google Scholar
  4. 4.
    H Ringsdorf and A Schneller. Synthesis, Structure and Properties of Liquid Crystalline Polymers. Brit.Pol.J. 13: 43 (1981).CrossRefGoogle Scholar
  5. 5.
    H Finkelmann, U Kiechle and G Rehage. Liquid Crystalline Side Chain Polymers in the Electric Field. Mol.Cryst.Liq.Cryst. 94: 343 (1983).CrossRefGoogle Scholar
  6. 6.
    H Ringsdorf and R Zentel. Liquid Crystalline Side Chain Polymers and their Behaviour in the Electric Field. Makromol.Chem. 183, 1245 (1982).Google Scholar
  7. 7.
    H Finkelmann, Liquid Crystalline Side Chain Polymers. Phil.Trans.R.Soc.Lond. A309: 105 (1983).ADSCrossRefGoogle Scholar
  8. 8.
    R Simon and H J Coles. Investigations of Smectic Polysiloxanes1 - Electric Field Induced Turbulence. Mol.Cryst.Liq.Cryst. 102 (Letts): 43 (1984).CrossRefGoogle Scholar
  9. 9.
    H J Coles and R Simon. Investigations of Smectic Polysiloxanes 2 - Field Induced Director Reorientation. Mol.Cryst.Liq.Cryst. in press (1984).Google Scholar
  10. 10.
    H J Coles and R Simon. Electro-Optic Effects in a Smectogenic Polysiloxane Side Chain Liquid Crystal Polymer, in “Recent Advances in Liquid Crystalline Polymers”, L L Chapoy (ed), Applied Science Publishers Ltd (Elsevier) London (1984).Google Scholar
  11. 11.
    E P Raynes, Electro-Optic and Thermo-Optic Effects in Liquid Crystals. Phil.Trans.R.Soc.Lond. A309: 167 (1983).Google Scholar
  12. 12.
    G W Gray, P A Gemmell and D Lacey, private communication.Google Scholar

Copyright information

© Springer Science+Business Media New York 1985

Authors and Affiliations

  • H. J. Coles
    • 1
  • R. Simon
    • 1
  1. 1.Liquid Crystal Group, Schuster Laboratory, Physics DepartmentUniversity of ManchesterManchesterUK

Personalised recommendations