Self-constructed stable liquid crystal alignment in a monomer-liquid crystal mixture system

Here, we demonstrate excellent liquid crystal (LC) vertical alignment without using an alignment layer printing process by introducing octadecyltrichlorosilane (OTS) into the LC mixture. Further, we investigated the alignment mechanism by analysing the surfaces of the substrates. The optimum concentration of OTS was found to be about 0.03 wt%, which is 1/100 of that in the previously reported polyhedral oligomeric silsesquioxane (POSS)-LC system. Moreover, the OTS-LC system exhibited a more stable LC alignment compared with the POSS-LC system. These differences may arise from the different strengths of surface-dopant interactions; that is, the covalent bond in the OTS-LC system and the van der Waals interactions in the POSS-LC system. We also demonstrated that the method can be used in a capillary tube, which may serve as a new method facilitating the application of LCs with curved surfaces.