Synergistic integration of squaramide‐hyperbranched porous organic polymer with poly(ionic liquid)s for enhanced atmospheric <scp> CO ₂ </scp> conversion

Abstract This study develops novel robust squaramide‐derived ionic hetero‐framework composites (denoted POP@PIL‐X; X = H, NH 2 , OH, COOH) via hyperbranched polymerization of dialdehyde/diamine monomers followed by in situ incorporation of task‐specific poly(ionic liquid)s. Comprehensive characterization confirms their structural integrity, high stability, and excellent porosity. These composites serve as efficient heterogeneous catalysts for the cycloaddition of CO 2 to epoxides toward the synthesis of cyclic carbonates. The impact of catalyst composition on catalytic activity was systematically evaluated, and the catalyst reusability along with substrate scope was investigated. Notably, the optimized POP@PIL‐OH catalyst exhibits exceptional performance in converting atmospheric CO 2 into various cyclic carbonates under metal‐, co‐catalyst‐, and solvent‐free conditions. Furthermore, this catalyst demonstrates excellent recyclability, maintaining high catalytic activity over five consecutive cycles without significant loss. Based on in situ Fourier transform infrared analyses and density functional theory calculations, a catalytic mechanism is proposed, involving synergistic interactions between multiple hydrogen‐bond donors and nucleophilic sites during the CO 2 cycloaddition reaction.