(1) Department of Physics, Kent State University, Kent, OH 44242, USA;(2) J. Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia;(3) Department of Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia
Abstract:
Using deuteron nuclear magnetic resonance to study liquid crystals confined
to cylindrical pores, an anchoring transition has been found. The transition
exhibits an unexpected sharp dependence of the anchoring strength on
cyanobiphenyl liquid crystal molecular length. A structural transition from
a parallel axial to a planar radial configuration occurs due to an anchoring
transition from planar to weakly homeotropic orientation at the walls. The
anchoring strength is at a minimum near the decylcyanobiphenyl (10CB)
liquid crystal length. Long chain liquid crystal configurations depend on
thermal cycling and on the equilibrium atmosphere leading to a bistable SmA
structure. Orientational order wetting in the isotropic phase also depends
on molecular length.