Study on Liquid Crystal Alignment and Structure of Aligning Additives by Neutron Reflectometry

Abstract

The advancement of LCD technology has greatly impacted our daily lives. Liquid crystal molecules exist in an intermediate state between liquid and crystal, and are stabilized by the domain structure of polar and non-polar portions, as well as the polarity of anisotropic molecules. In order to use liquid crystals for displays, they must be uniformly oriented. However, achieving this requires an alignment agent to be applied to the substrate in a clean environment, followed by heat treatment, which increases the number of processes and limits the number of substrates that can be used. Recently, there has been a lot of attention on alignment agents that can induce alignment simply by mixing with the liquid crystal and adsorbing to the substrate. In this study, neutron reflectivity measurements were conducted to investigate the liquid crystal structure and the structure formed by the alignment agent. The results showed that the model alignment agent adsorbs on the substrate to form a monolayer, and that the structure changes from horizontal to vertical with increasing mixing concentration.