Investigation of CO2 Absorption Enhancement in Polymers/Ionic-Liquids Systems

The demand for energy has been growing due to the economic, technological growth, and human’s activities. This growing demand and the reliance on the fossil fuels, as the major energy resource, lead to the increase in the emission of the greenhouse gases. Current methods of CO₂ capture rely on amine solutions for which they are challenges associated with the amine regeneration, toxicity, and high energy cost. To mitigate these challenges, many efforts are on-going to utilize new materials for CO₂ capture. Among the new materials and technologies, Ionic liquids (ILs) are promising candidates for CO₂ capture and storage applications because of their unique properties such as thermal stability, nontoxicity, and low volatility. Nevertheless, ILs’ usage has been hindered by their high viscosity. This problem can be circumvented by either changing the separation scheme through making absorbents for pressure swing processes or increasing the fluoroalkyl chain in the anion in order to reduce the high viscosity of ILs. To formulate absorbents, ILs can be immobilized within polymers matrix. Recent studies demonstrated the role of interfacial phenomena and ILs ordering, and its influence on gas sorption in ILs mixture in polymers. Here, to elucidate the mechanism of CO₂ absorption in IL/polymer, we investigated the effect of mixtures composition on macromolecular restructuring of polymer phase and its impact on CO₂ sorption. In this study, we utilized 2D nanosheets, such as graphene and MXenes as fillers, and evaluated CO₂ absorption in thin films of polymer/Ionic Liquids composite. By utilizing gravimetric methods, via using the high-precision Quartz Crystal Microbalance (QCM), we established correlations between the order parameter of the system along with its composition and its gas sorption capacity. Our results indicated that the degree of crystallinity and the distribution of charge at interphase of polymer/IL, defining the density of free ions and the cohesion forces within the ILs phase, are the controlling parameters defining CO₂ absorption capacity of these mixtures.