Issue
EPL
Volume 83, Number 6, September 2008
Article Number 66004
Number of page(s) 5
Section Condensed Matter: Structural, Mechanical and Thermal Properties
DOI http://dx.doi.org/10.1209/0295-5075/83/66004
Published online 09 September 2008
EPL, 83 (2008) 66004
DOI: 10.1209/0295-5075/83/66004

Line tension of nematic pancakes at the air-water interface: Static and dynamic measurements

U. Delabre1, 2, C. Richard2, J. Meunier1 and A.-M. Cazabat1, 2

1   Laboratoire de Physique Statistique - 24 Rue Lhomond 75231 Paris Cedex 05, France, EU
2   Université Pierre et Marie Curie - 4 place Jussieu 75252 Paris Cedex 05, France, EU

anne-marie.cazabat@upmc.fr

received 13 June 2008; accepted in final form 29 July 2008; published September 2008
published online 9 September 2008

Abstract
The line tension of nematic Langmuir films on water is investigated using the 6CB member of the cyanobiphenyl liquid-crystals series. Both static and dynamic measurements are performed independently. The line tension increases linearly with film thickness up to 0.2 $\mu$m. The increment of line tension is significantly smaller than for the smectic 8CB compound, due to the difference in the allowed elastic deformations of smectic and nematic films. A simple model of the nematic edge accounts both for the linear dependence and the order of magnitude of the line tension. Moreover, it sheds new light on the structure of thin nematic films on liquid substrates.

PACS
61.30.-v - Liquid crystals.
68.18.-g - Langmuir-Blodgett films on liquids.
47.57.-s - Complex fluids and colloidal systems.

© EPLA 2008