Hybrid Alkoxysilane-Functionalized Urethane-Imide-Based Poly(ionic liquids) as a New Platform for Carbon Dioxide Capture

Development of new and improvement of the existing materials for carbon dioxide (CO2) capture is an urgent and significant goal for emission reduction. We hereby report synthesis of hybrid urethane-imide-based poly-ILs (HPILs) and their CO2 capture capacities. The synthesized HPILs were characterized by Fourier transform infred (FTIR), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), dynamic mechanical thermal analysis (DMTA), atomic force microscopy (AFM). CO2 physisorption and reusability were assessed by the pressure-decay technique at a few conditions. Density functional theory calculations were used to identify binding energies between CO2 and each center of HPILs. Cations of HPILs play an important role in CO2 physisorption. The impact of the silane content was found to be relatively insignificant. Weakly coordinating cations foster better CO2 sorption. The best performances were obtained for the tetrabutylammonium-based HPILs (33.1 mg/g in HPIL-02-TBA and 31.7 mg/g in HPIL-06-TBA at 303.15 K and 0.82 bar). HPIL-02-TBA possesses the highest CO2 sorption capacity out of all reported poly(ionic liquids) thus far and exhibits interesting thermal stability and competitive mechanical properties. Application of HPIL-02-TBA will lead to more robust CO2 capturing setups.