Ionic liquids (ILS) are a rapidly evolving class of material that has potential impacts as solvents, battery electrolytes, robotics and actuators, catalysts, and biomedical therapeutics. Additionally,…

This is a $600,000.00 grant awarded by the National Aeronautics and Space Administration (NASA) to Arizona State University (ASU) to conduct research on ionic liquids (ILs) and their potential applications in areas such as solvents, battery electrolytes, robotics, and carbon dioxide capture. The grant focuses on designing new support materials, processing them into large surface area carbon dioxide capture media, and engineering their performance to improve the current state-of-the-art. The project aims to prepare lightweight, robust, and processable charged polymeric membranes capable of high IL loading with no IL leaching or blowout, optimize carbon dioxide permeability and selectivity against nitrogen, oxygen, and water, and study the scale-up, processing, and techno-economic performance of the membranes in a microgravity environment. The project is expected to run until September 30, 2023, and there is no set-aside designation associated with this award.

Ionic liquids (ILS) are a rapidly evolving class of material that has potential impacts as solvents, battery electrolytes, robotics and actuators, catalysts, and biomedical therapeutics. Additionally, ILS have been investigated for their abilities to selectivity dissolve gases, including carbon dioxide. These molten salts offer several beneficial attributes, including fixed charge, tunable molecular structures (i.e., designer solvents/agents), negligible volatility, and relatively high thermal stability. The hydrophilicity, dielectric constant, and many other attributes can be altered by tuning the molecular structure (both cation and anion can be significantly varied), yielding task-specific ionic liquids for the many applications noted above. The incorporation of ILS into various membrane processes has been gaining attention over the past decade. These supported ionic liquid membranes (silms) have been used for selective CO2 capture, though primarily selective against CH4 or N2. Additionally, common concerns for their commercial or industrial implementation include 1) IL blow-out, when the pressure drop across the membrane causes the IL to leave the polymeric support and 2) thick membranes, which limits transport. This project will focus on designing new support materials, processing them into large surface area CO2 capture media, and engineering their performance to improve the current state-of-the-art. Specifically, the scientific objectives of this proposed project are: 1) prepare lightweight, robust, and processable charged polymeric membranes capable of a high IL loading with no demonstrable IL leeching or blowout, 2) optimize CO2 perm-selectivity against N2, O2, and H2O, and 3) study the scale-up, processing, and techno-economic performance of the membranes in a microgravity environment. A series of poly(arylene ether sulfone)s will be prepared comprising the monomer diallyl bisphenol a. This monomer contains a pendant allyl functionality, which can be functionalized using thiol-ENE "click" chemistry to introduce added functionality. Charged sites will be added to the polysulfone backbone, which will promote IL retention and increase the IL loading capacity. The membrane characteristics will be characterized with dynamic mechanical analysis, electrochemical impedance spectroscopy, atomic force and scanning electron microscopy, size exclusion chromatography and positron annihilation lifetime spectroscopy. Structure-property relationships will be established, in particular related to surface roughness and membrane free volume, to the CO2 capture. The membranes will then be processed using various solution casting techniques to study membrane porosity and the impact on IL loading, CO2 capture and transport, and membrane stability. The IL [1-butyl-3-methylimidazolium][BIS(trifluoromethylsulfonyl)imide] will be impregnated into the membrane, based on its demonstrated ability to selectively dissolve CO2. The CO2 perm-selectivity and transport properties (temperature- and pressure-dependent flux) will be characterized and the system will be optimized. Finally, the prototype design will be assembled in a way that enable ease of installation and operation, a high CO2 scrubbing capacity with limited power consumption, and integration with future technologies (e.g., catalytic formation of CH4 or other carbon-based materials of interest).