A theoretical analysis of homeotropic alignment induced by nanoparticles
(NPs) in a nematic liquid crystal (NLC) sample cell is presented. It is found
that such alignment on the surface of a NP causes a change in the orientation
of the molecular director near the surface, which in turn induces variations in
the elastic constants and free energy. The induced NLC properties allow
coupling between nearby NPs, mediated by the NLC molecules. The rotation of the
coupled NPs close to the substrate tends to induce a long-range orientation of
the NLC molecular director, leading to modification in the alignment at the
interface of NLC and substrate which induces the orientation from homogeneous
(planar) to homeotropic (vertical) in the bulk material.
