(260ad) Cuboidal Colloidal Particles in Nematic Liquid Crystal: Defect Structures and Self-Assembly

The physics of the nematic topological defects around sphere solid particles, and their defect induced self-assembly have been extensively investigated in past years. Here, we examine experimentally and theoretically, the effect of edge curvature of colloidal particles with homeotropic surface anchoring on their defect configuration and self-assembly in a nematic liquid crystal. Our computational studies indicate that the gradual increase of the edges sharpness from sphere to cube modifies the defect structure from a Saturn ring to a distorted ring with sharp bends, which is pinned to the edges of the cube particle. In agreement with our computational results, the polarized light microscopy images show reshaping of the defect ring around the cuboidal particles immersed in 5CB nematic liquid crystal. Moreover, calculation of the pair potential interaction for colloidal cubes indicates that the presence of sharp edges can significantly affect the interaction between particles and their eventual self-assembly in the nemtic liquid crystal. The wide variety of topological defects achievable by changing the curvature could provide new tools to tune colloidal self-assembly.