Separating trace propyne from propylene is of great importance in the petrochemical industry but difficult because of very close molecular sizes and physicochemical properties, which promotes the development of high-performance porous materials with great stability in practical adsorptive separation; however, a limited number of efficient adsorbents have been reported. Here, a class of robust functionalized ionic ultramicroporous polymers (IUPs) with different branched structures that feature high-density preferential anionic binding sites and outstanding thermal and water stability is systematically studied for the separation of propyne and propylene for the first time. The functionalized pore environment of IUPs achieves the highest selectivity of propyne and propylene (126.5) for the 1/99 (v/v) mixture among porous organic polymers, as well as excellent and recyclable dynamic separation performance. Modeling studies reveal that strong basic sites of IUPs with abundant ultramicroporosity facilitate the efficient removal of propyne from propylene. This study provides important clues for the design of robust functionalized adsorbents and thus expands the currently limited dictionary of adsorbents for the separation of important gas mixtures.

Porous ionic polymers have demonstrated great potential for high-performance separation by the merits of their unique molecular recognition, but the preparation of anion-functionalized ionic polymers for the separation of bioactive molecules with highly similar structures remains a challenge. Here, through the facile Friedel-Crafts alkylation between benzylimidazole ionic liquids (ILs) and crosslinkers, several anion-functionalized hypercrosslinked ionic porous polymers (HIPs) are reported, which are well decorated with strongly basic carboxylate anions as well as feature tubular morphology and excellent thermal stability. High adsorption capacity (103.6 mg g −1 for tocopherol homologues) and selectivity (S β&γ/α , 4.26; S δ/α , 3.19) for bioactive compounds with high structural similarity have been realized, superior to those of commercial adsorbents, hypercrosslinked polymer without ILs, and HIPs with common ILs. This study manifests a new synthetic strategy and rational molecular design for functionalized adsorbents, as well as offers new opportunities to enable high-performance separation.

Precise engineering of organic porous polymers to realize the selective separation of structurally similar gases presents a great challenge. In this study, a new class of ionic porous polymers P(Ph3Im-Br-nDVB) with a high ionic density and microporous surface area are constructed through a facile copolymerization strategy, providing an efficient path to rational control over pore structure and functionality. The first example of ionic porous organic polymers is reported to address the challenge of discriminating the subtle difference of C 2 H 2 and CO 2 , which have almost identical molecular sizes and similar physicochemical properties, which achieve the highest C 2 H 2 / CO 2 selectivity (17.9) among porous organic polymers. These ionic porous polymers exhibit high stability and excellent dynamic breakthrough performance for binary C 2 H 2 /CO 2 mixtures, indicating their practical feasibility. Modeling studies reveal that anions are the specific binding sites for preferential C 2 H 2 capture because of Br − •••HCCH interactions. This study not only demonstrates an efficient strategy to build novel ionic porous polymers integrating abundant micropores and ionic sites but also sheds some light on the development of functionalized materials for the separation of structurally similar gas molecules.

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