<title>Role of subsurface elastic phenomena on the macroscopic properties of nematic liquid crystals</title>

Abstract

In this paper we give a short review of some recent theoretical results on the interfacial and surface properties of nematic liquid crystals (NLCs). By using a phenomenological and a molecular model, we show that the surface free energy of nematic liquid crystals contains new specific elastic and geometric terms. Furthermore we show that surface elastic terms that depend on the director derivative along the normal to the interface cannot enter a macroscopic theory of NLCs. Then, we propose a new expression of the surface free energy Fs that does not contain normal director derivatives. Fs contains four independent contributions: a classical anchoring energy, two new geometric surface terms that depend on the two local curvature radii and an elastic term formally equivalent to the classical K24 term. The new free energy is bounded from below and always admits a minimizing director field. All these surface terms can be measured by making suitable experiments on NLCs in spherical or cylindrical cavities.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.