Conferring Poly(ionic liquid)s with High Surface Areas for Enhanced Catalytic Activity

Three ionic liquid (IL) monomers consisting of one, two, and four benzene rings were designed with 2-phenylimidazole and polymerized with α,α′-dichloro-p-xylene (DCX) and formaldehyde dimethyl acetal (FDA) to form a series of novel poly(ionic liquid)s (PILs). In this process, the designed ILs were employed as active ionic sites, and DCX and FDA were selected as cross-linkers. Self-condensation of the cross-linker provided a large specific surface area for the hypercross-linked organic framework, while co-condensation between the cross-linker and IL introduced active sites to the framework. The obtained porous hypercross-linked PILs not only promoted CO2 capture and the selective absorption of CO2/N2 but also showed good activity for the cycloaddition of epoxide with CO2. HP-[BZPhIm]Cl-DCX-1 with a large surface area (763 m2·g-1) showed a CO2 uptake capacity of 1.47 mmol·g-1 and offered a 98.9% yield of the CO2 cycloaddition product with epichlorohydrin at 80 °C for 24 h under 0.1 MPa CO2 pressure. The designed PILs provide an important reaction for CO2 utilization.