(179a) Elastic Induced Colloidal Interactions in Liquid Crystals

In this work, we exploit well defined boundary conditions to control the formation of defects in nematic liquid crystal (NLC) 5CB. When supported between micropost arrays, disclination lines form and bear the signature of the micropost shape owing to the elasticity of the medium. The existence of these disclination lines can be tuned due to the thermotropic nature of the material simply by varying temperature thereby providing an element of control not present in typical isotropic fluids. When colloids are introduced to a nematic liquid crystal, elastic distortions arise that have an associated Frank free energy cost. This excess energy is reduced by interacting with the micropost induced disclination lines and subsequent colloid-micropost attractions arise. We consider both isotropic particles (spheres) and more complex anisotropic particles. Further, we observe these effects 5CB-air interfaces as well as in bulk 5CB. This work is experimental and supplemented with analysis to support the observed behavior.