Eur. Phys. J. E (2010) 31: 343-349
https://doi.org/10.1140/epje/i2010-10586-2

Regular Article

Morphology of open films of discotic hexagonal columnar liquid crystals as probed by grazing incidence X-ray diffraction

¹ Centre de Recherche Paul-Pascal, Université de Bordeaux, 115 Avenue Schweitzer, 33600, Pessac, France
² Insitut des Nanosciences de Paris, Universités Paris 6 et 7, 140 Rue de Lourmel, 75015, Paris, France
³ Université Paris 5 René Descartes, 45 rue des Saints Pères, 75231, Paris Cedex 06, France

^* e-mail: grelet@crpp-bordeaux.cnrs.fr

Received: 12 January 2010
Revised: 24 February 2010
Accepted: 3 March 2010
Published online: 10 April 2010

Abstract

The structure and the orientation of thermotropic hexagonal columnar liquid crystals are studied by grazing incidence X-ray diffraction (GIXD) for different discotic compounds in the geometry of open supported thin films. Whatever the film deposition mode (either spin-coating or vacuum evaporation) and the film thickness, a degenerate planar alignment with the liquid crystalline columns parallel to the substrate is found. However, if a specific thermal process is applied to the liquid crystal film, homeotropic anchoring (columns normal to the interface) can be stabilized in a metastable state.