Cross-linked, porous imidazolium-based poly(ionic liquid)s for CO₂capture and utilisation

CO₂is the most influential greenhouse gas with drastic effects all over the world. Meanwhile, global warming is considered a hot topic to different groups of scientists dealing with the global warming phenomenon. As an alternative to the typically-used scrubbing agent that is heavily used in post-combustion capture technology, namely, monoethanolamine, with its well-known drawbacks, the ionic liquids (ILs) and their corresponding polymers,viz., poly(ionic liquid)s (PILs) have been exploited. In this study, we constructed new imidazolium-based PILs with high surface area fabricated from a 3-(3-(phthalimide)propyl)-1-vinylimidazolium bromide IL-precursor withN-allylphthalimide building blocks, in the presence of divinylbenzene serving as a cross-linker, through a free-radical polymerisation process, and provide their ability for the dual purposes of CO₂capture and utilisation. In this context, the chemical structure of the monomers was fully characterised using elemental analysis, nuclear magnetic resonance and attenuated total reflectance-infrared spectroscopy. The polymeric materials were further examined by thermogravimetric analysis, the Brunauer-Emmett-Teller model and scanning electron microscopy. The sorption characteristics of the amine functionalised PILs were measured volumetrically with CO₂uptake values up to 0.59 mmol CO₂per g sorbent under RTP conditions (25 °C and 1 bar). For CO₂utilisation purposes, the molar ratio of the ionic residues within the polymeric scaffold was increased ranging from one- and two- up to four-fold (×1, ×2, ×4), respectively. Remarkably, the polymeric materials showed excellent catalytic activity for the cycloaddition of CO₂with epoxides to synthesise cyclic carbonates with almost quantitative conversion at 10 bar CO₂and 110 °C.