Surface molecular anchoring in microconfined liquid crystals near the nematic–smectic-Atransition
- 1 September 1993
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review E
- Vol. 48 (3) , 1998-2005
- https://doi.org/10.1103/physreve.48.1998
Abstract
The effect of the diverging bend elastic constant, , on the nematic director field of 4’-octyl-cyanobiphenyl (8CB) in submicrometer cylindrical cavities in a polycarbonate matrix, as the nematic–smetic-A phase transition is approached, is investigated with deuteron nuclear magnetic resonance H-NMR). The spectra and the use of Frank elastic theory enable us to monitor the actual surface anchoring angle profile, determine the density of point defects in the escaped structure, and estimate the anchoring strength to be =7× J/, which is temperature independent. The large value of and the lack of evidence for pretransitional smectic layering in our NMR spectra show that although the orientational anchoring is strong, the polycarbonate surface is too rough to induce substantial surface smectic order in the nematic phase. The saddle-splay elastic constant for 8CB is estimated to be larger than the elastic constant .
Keywords
This publication has 24 references indexed in Scilit:
- Surface elastic and molecular-anchoring properties of nematic liquid crystals confined to cylindrical cavitiesPhysical Review A, 1992
- Determination of the liquid-crystal surface elastic constantPhysical Review Letters, 1991
- Finite molecular anchoring in the escaped-radial nematic configuration: AstudyPhysical Review A, 1991
- Defect structures of nematic liquid crystals in cylindrical cavitiesPhysical Review A, 1991
- Escaped-radial nematic configuration in submicrometer-size cylindrical cavities: Deuterium nuclear-magnetic-resonance studyPhysical Review A, 1991
- On the existence of even indexed disclinations in nematic liquid crystalsPhilosophical Magazine, 1973
- Screw Disclinations in Nematic Samples with Cylindrical SymmetryMolecular Crystals and Liquid Crystals, 1973
- Disclinations and Properties of the Directorfield in Nematic and Cholesteric Liquid CrystalsMolecular Crystals and Liquid Crystals, 1973
- NonsingularScrew Disclination Lines in NematicsPhysical Review Letters, 1972
- Non-singular disclinations of strength S = + 1 in nematicsJournal de Physique, 1972