Design of functional thermotropic liquid crystals: Luminescent trimeric, and polymerizable bent-core mesogens

Applications of thermotropic liquids crystals have largely been involved with liquid crystal displays. Incorporation of novel physical properties into liquid crystal phases could lead to a much wider array of applications, but is difficult, due to the delicate nature of the liquid crystalline phase. In this thesis, we present some new approaches for designing such functional liquid crystals. Chapters Two and Three cover a series of compounds with a trimeric design, which has three rigid sections separated by flexible alkyl chains. In our design, the liquid crystalline and functional portions of the molecule are physically separated to simplify design. In these molecules, a non-mesogenic structure that possesses strong fluorescent behavior was coupled to mesogenic groups to create a liquid crystalline molecule that is inherently luminescent. The smectic liquid crystalline phase exhibited by the molecule is capable of being shear aligned, and exhibits partially polarized fluorescence when aligned and excited with unpolarized light. Chapters Four and Five cover the first example of a polymerizable bent-core mesogen, which allows the production of ordered polymeric materials with properties such as piezo- and pyroelectricity. The compounds produced exhibited a switchable smectic liquid crystalline phase that can be aligned under relatively low electric fields and cross-linked to give a polymer that possesses pyroelectric behavior.