# Polymeric and Crystalline Materials for Effective and Sustainable CO\({}_{2}\) Capture
## 2 Background
### CO\({}_{2}\) Capture Using Adsorbents and Membranes
Permeance is commonly expressed in units like gas permeance (e.g., GPU--gas permeation units, with 1 GPU corresponding to \(10^{-6}\) cm\({}^{3}\)(STP)/(cm\({}^{2}\)-s-cmHg)) for gas separations, and it can vary significantly depending on the type of polymer, the substance being permeated, and the conditions like temperature and pressure [41].This concept is crucial in the design of membranes for gas separation, filtration, and various industrial applications. Several polymeric membranes showed interesting capabilities for the selective permeation of nitrogen and carbon dioxide [42]. For instance, oxygen-rich polymers, polymeric ionic liquids, perfluoro polymers, and iptycene-based polymers are a few examples of performing membranes for CO\({}_{2}\)/gas separation [42; 43; 44; 45]. More precisely, it is well known that a high content of ether oxygen enhances the CO\({}_{2}\) affinity via the creation of a quadrupole-quadrupole interaction [46]. [PERSON] and coworkers recently reported that a highly branched amorphous polymer incorporating a 1,3-dioxolane unit exhibited excellent CO\({}_{2}\)/N\({}_{2}\) separation properties [47]. Likewise, crosslinked polyethylene glycol (PEG) derivatives prepared by [PERSON] et al. have been shown to hinder the diffusion of CH\({}_{4}\), thus improving the CO\({}_{2}\)/CH\({}_{4}\) selectivity [48]. As mentioned, polymeric ionic liquids showed potential for CO\({}_{2}\)/N\({}_{2}\) and CO\({}_{2}\)/CH\({}_{4}\) separations. They can be defined in several categories such as ion-gel membranes, poly(ionene)s, and poly(ionomer)s [49; 50; 51]. [PERSON] and coworkers recently reported a PEG-diacrylate incorporating a 2-aminoethyl motif [52]. Several ionic liquids were blended with the polymer network, demonstrating targeted selectivity towards CO\({}_{2}\) in the presence of N\({}_{2}\). [PERSON] et al. reported the preparation of a novel rigid polyamide-ionene material (Im-TB-PA ionene) using Menshutkin reactions between \(N\),\(N^{\prime}\)-(1,4-phenylene)bis(4-(chloromethyl)benzamide) and dimidazole-functionalized Troger's base monomers [53]. The resulting membrane displayed excellent selectivity for CO\({}_{2}\). [PERSON] et al. studied the catalytic activity and CO\({}_{2}\) kinetic separation performances of anionic ionomer-based membranes utilizing an N\({}_{2}\), O\({}_{2}\), and CO\({}_{2}\) gas mixture [54]. Perfluoropolymers are fluorinated polymers with C-H bonds replaced by C-F bonds. In terms of CO\({}_{2}\) separation, several derivatives have been studied [55; 56]. For example, the gas separation of perfluoro(butenyl vinyl ether)co-perfluoro(2,2-dimethyl-1,3-dioxole) polymer was reported [57]. The resulting polymeric membrane showed increasing H\({}_{2}\)/CO\({}_{2}\) selectivity with temperature. Another example is the iptycene polymers, a class of 3D materials incorporating a [2,2,2]bicyclooctatriene moiety. In terms of CO\({}_{2}\) separation, these materials have shown promising results as reported by [PERSON] et al. [58; 59]. In particular, the authors studied a triptycene rearranged-polybenzoxazole (TR-PBO) polymer membrane for highly selective and permeable gas separation membranes with potential for H\({}_{2}\) purification and CO\({}_{2}\) removal from natural gas [60].