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Boronic Ester-Containing Discotic Liquid Crystals: From Tunable Electronics to Templates for Nanoporous Membranes
AdvisorKing, Benjamin T.
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This dissertation describes the use of discotic liquid crystals for two different areas of research, advances in new organic photovoltaic cell (OPVC) technologies and the development of new nanoporous membranes.Discotic liquid crystals (DLCs) generally consist of a central polycyclic aromatic hydrocarbon core that is generally ridged and crystalline in nature. The central core is decorated with alkyl chains in order to induce liquid crystallinity. Within their mesophase, DLCs spontaneously form columnar structures with close intracolumnar disc-disc distances. Due to the close disc-disc packing, the conjugated, aromatic cores act as one-dimensional charge carriers. The spontaneous alignment of DLCs is ideal for electronic applications, namely OPVCs. We describe the synthesis of a new boronic ester containing discotic liquid crystal that is highly electron deficient and displays high charge carrier mobilities.The scope of the boronic ester formation and its application to liquid crystals was explored with the development of two new boronic ester containing non-planar discotic liquid crystals. A new approach toward completely DLC-based OPVCs is described and explored. The miscibility of the non-planar discotic liquid crystals with planar discotic liquid crystals, which is a key requirement for the alignment of the desired OPVC was tested.In many membranes used for industrial applications a great deal of energy is put into forcing materials into certain alignments. However, in our approach toward a DLC-based nanoporous membrane we utilize the spontaneous alignment of liquid crystals in order to make desirable molecular architectures. By adding polymerizable units to the periphery of a DLC we "lock" the mesophase alignment upon polymerization. Due to the highly labile nature of the boron-oxygen bonds that surround the central core of our boronic ester-containing DLC were are able to then remove the DLC cores, revealing a nanoporous membrane templated by the DLC mesophase alignment. The polymerized material with the cores removed has a remarkably high pore density, contains only one pore size, and has linear pores templated by the columnar DLC mesophase.