New ionic liquids and ionic liquid-based polymers and liquid crystals for gas separations

Membrane-based gas separations are of great importance to industry, society and the environment. Global energy demand will continue to increase for the foreseeable future, and chemical separations with improved efficiencies will aid in curbing fuel use. Membranes potentially offer less energy intensive alternatives to traditional separation technologies. Proper design considerations are needed to engineer high-performance materials that selectively segregate specific components from a mixture based on affinity, shape, size, charge or other chemical and physical properties. However, much research is still needed in order for membranes to be economically viable and displace older technologies.; Separations involving light gases (CO2, N2, O 2, CH4, H2, small hydrocarbons, etc.) will be crucial to the realization of the everyday use of renewable fuels and independence from foreign oil. These political issues coupled with growing social concern and desire for clean, sustainable technologies will drive research into and the implementation of membrane-based gas separations.; The research presented here is unique in that it takes a bottom-up approach to design---materials are created specifically with CO2-based separations in mind. Several related classes of materials that represent radical new approaches to gas separations are employed: room temperature ionic liquids (RTILs), polymerizable RTILs for solid-state membranes, and nanostructured lyotropic liquid crystals (LLCs). Each class possesses great potential to separate light gases, and has unique features that are just beginning to be explored.; Several, widely applicable facts important to advancing gas separation technology have been realized during the course of this research: The inclusion of extra polar groups in RTILs allows for enhanced separation selectivity between CO2/N2 and CO2/CH4, while maintaining high CO2 loading levels. Fabrication of poly(RTIL) membranes can further enhance CO2 solubility compared to RTILs and traditional polymers. The use of LLC-based membranes gives improved performance in CO2-based separations relative to analogous, isotropic structures. The realization of each of these relationships can potentially have broad impacts on research into materials for gas separations.