Modeling planar degenerate wetting and anchoring in nematic liquid crystals

Abstract

We propose a simple surface potential favoring the planar degenerate\nanchoring of nematic liquid crystals, i.e., the tendency of the molecules to\nalign parallel to one another along any direction parallel to the surface. We\nshow that, at lowest order in the tensorial Landau-de Gennes order-parameter,\nfourth-order terms must be included. We analyze the anchoring and wetting\nproperties of this surface potential. In the nematic phase, we find the desired\ndegenerate planar anchoring, with positive scalar order-parameter and some\nsurface biaxiality. In the isotropic phase, we find, in agreement with\nexperiments, that the wetting layer may exhibit a uniaxial ordering with\nnegative scalar order-parameter. For large enough anchoring strength, this\nnegative ordering transits towards the planar degenerate state.\n