Director textures of the Nèel inversion wall in a liquid crystal polymer

Abstract

A solution of the director orientation function is presented for Nëel inversion walls created in a liquid crystal by application of a magnetic field. The theoretical model is used to simulate director trajectories across walls as a function of both the elastic anisotropy and the orientation of the wall with respect to the applied field. The gradual transition of the defect structures from Nëel bend walls to Nëel splay walls as the angle between the wall and the magnetic field is varied is also presented. Micrographs obtained via atomic force microscopy on a thermotropic liquid crystalline polymer are used to test and evaluate the theoretical model. Visualization of director textures using the lamellar decoration technique shows the theoretical and experimental results to be in good agreement. The results were used to determine that the sample had an elastic anisotropy of approximately 0.5, implying that k₁₁ = 3k₃₃.