Periodic Planar‐Homeotropic Anchoring Realized by Photoalignment for Stabilization of Chiral Superstructures

Abstract Self‐organization of chiral superstructures in liquid crystal (LC) materials is a powerful tool in developing functional devices based on soft matter. The control and manipulation of the helical axis orientation in chiral nematic liquid crystals are currently attracting significant attention, but are hindered by limited control over the anchoring at the interfaces. The development of new alignment techniques with local control over polar and azimuthal anchoring can open up a wide range of possibilities. Here a new photoalignment process based on a mixture of photosensitive azo compounds and homeotropic alignment materials is developed and demonstrated. The alignment of the LC director near the surface depends on both intensity and polarization of the UV illumination. By two‐beam interference UV illumination, periodic stripes of planar and homeotropic anchoring are realized. In addition it is demonstrated that the stripes of planar and homeotropic anchoring stabilize and align cholesteric fingers in cells with thickness smaller than the pitch. The 2D director configuration in the cholesteric fingers is identified by matching the experimental observations with numerical simulations based on finite element Q‐tensor calculations.