The Effect of Polymer Properties on Carbon Dioxide Absorbance Capacity of Supported Ionic Liquid Membranes

With today's energy demands, our dependence on fossil fuels has grown significantly. This leads to devastating consequences for our environment and ecosystem, resulting in global warming. To address the generated carbon footprint, carbon capture techniques, such as absorption using amine systems, are implemented. This technology has limitations in terms of operational and environmental efficiency, toxicity, and operational costs. One promising candidate is to utilize a greener alternative, such as Ionic Liquids (ILs). As green solvents with low vapor pressure, high thermal stability, tunable structure, low flammability, and high affinity for CO2, ILs are a great solution to replace conventional carbon capture technologies. Several recent studies have demonstrated enhanced CO2 solubility for confined ionic liquids within polymeric domains, suggesting a potential for stabilizing ILs within macromolecular domains and taking advantage of their non-ideal properties. With the potential for ILs to be incorporated into polymeric domains, understanding the underlying phenomena that govern their non-ideal properties is a critical task. In this study, the effect of the molecular weight (MW) of polymer on the CO2 adsorption capacity of supported ionic liquid membranes (SILM) was investigated. Quasi-solid-state films were cast from mixtures containing 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide and Polyvinylidene Fluoride (PVDF) with different Molecular Weight (MW) of 180K and 534K, and the solubilities of CO2 in these films were measured using a microgravimetry method with a Quartz Crystal Microbalance. The adsorption isotherms were obtained at four different temperatures. Our result indicates that the MW of PVDF has a significant impact on the CO2 solubility in SILMs, highlighting the importance of the intermolecular interaction and swelling properties of polymer on CO2 sorption within the mixture. According to our findings, the 1:1 IL-polymer mixture prepared with 180K polymer presents the greatest promise for fabricating SILMs.