Controllable alignment of liquid crystals based on the surface relief gratings from a photocross-linkable organic monomer

The orientational control of liquid crystal (LC) molecules is essential for high-quality liquid crystal displays, and the photo-induced surface relief grating (SRG) is a facile and effective non-contact process. Here, SRGs with different period and depth were prepared with a photocross-linkable organic monomer 4-propyldiphenylacetylenecarboxylic acid cinnamyl ester (PDACE), and the LC alignment induced by SRG was studied. It is found that both the surface topography and the chemical nature of the surface are responsible for the LC alignment, which is strongly dependent on the groove geometry of the gratings. Furthermore, the patterned LC cell was fabricated with the patterned SRG surface. These results demonstrate that the planar, perpendicular and patterned orientations of LC can be easily photo-controllably obtained with PDACE, which have important applications in optical devices.