Director configurations in nematic droplets with inhomogeneous boundary conditions

The nematic droplets with director configurations intermediate between the bipolar and radial structures have been investigated experimentally and theoretically. The liquid crystal 4'-n-pentyl-4-cyanobiphenyl (5CB) with a variable addition of the lecithin dispersed in polyvinylbutyral has been used. The characteristic textures of the droplets formed at various lecithin contents have been examined using polarizing microscope both in the crossed polarizers and without analyzer. The computer simulation has been performed for proper ordering of the director in spherical nematic droplets by minimizing the free energy in the one-constant approximation. The inhomogeneous boundary conditions with strong anchoring of the molecules at the interface have been used. The distribution of the anchoring angle at the droplet surface has been estimated based on analysis of observed patterns. The simulated textures of the droplets under crossed polarizers are shown to compare well with the experimental ones.