Regular arrays of topological defects within nematic liquid crystals by colloidal assembly

The incorporation of spherical colloidal particles into liquid crystalline films has sparked both fundamental and applied interest as a promising way to control and explore their topological defects. To date, most research has focused on free particles in liquid crystals, which tend to aggregate in order to minimise the elastic distortion energy they induce in the surrounding anisotropic media. However, creating and maintaining defect arrays by particle patterning offers significant promise for further control. By utilising capillarity-assisted particle assembly (CAPA) to fix colloidal particle arrays into a well-aligned nematic LC environment, we demonstrate that we can create static and reproducible patterns of topological defects. Depending on the material of the particles, they can either be sintered onto a glass surface or be directly transferred onto a substrate via a polymer anchoring layer. We demonstrate a large library of different anchoring conditions by selectively functionalising particles and substrates with different alignment materials. Finally, by sequential particle assembly steps, we can combine various colloids within a single pattern, leading to the coexistence of multiple of defects in controlled patterns. This study demonstrates a versatile method to control defect structures within liquid-crystalline films, opening up new possibilities for further studies in defect-dominated systems. [GRAPHICS] .