Poly(ionic liquid) (PIL) catalysts with swelling ability and water enrichment ability in water/ethylene carbonate (EC) mixed substrates were designed and synthesized via a one-step direct radical copolymerization of N-vinylimidazolium IL monomers, sodium acrylate and crosslinkers. The structure and morphology of the PILs were characterized by NMR, FT-IR, TGA, SEM and elemental analysis. The effect of substituent groups and crosslinkers on the swelling ability and water enrichment ability of PILs in water and EC was studied. The water enrichment ability of PILs was positively related to the hydrophilicity of 3-substituents on imidazoliums and the crosslinkers, and water could be absorbed inside quantitatively. These PIL catalysts could enrich the optimal ratio of water to EC inside and act as high-efficiency microreactors for the catalytic hydrolysis of EC. The water enrichment ability of PIL microreactors was helpful for the decrease of water amount and the increase of catalytic efficiency.

Coordination cages have been widely reported to bind a variety of guests, which are useful for chemical separation. Although the use of cages in the solid state benefits the recycling, the flexibility, dynamicity, and metal-ligand bond reversibility of solid-state cages are poor, preventing efficient guest encapsulation. Here we report a type of coordination cage-integrated solid materials that can be swelled into gel in water. The material is prepared through incorporation of an anionic Fe^II₄L₆ cage as the counterion of a cationic poly(ionic liquid) (MOC@PIL). The immobilized cages within MOC@PILs have been found to greatly affect the swelling ability of MOC@PILs and thus the mechanical properties. Importantly, upon swelling, the uptake of water provides an ideal microenvironment within the gels for the immobilized cages to dynamically move and flex that leads to excellent solution-level guest binding performances. This concept has enabled the use of MOC@PILs as efficient adsorbents for the removal of pollutants from water and for the purification of toluene and cyclohexane. Importantly, MOC@PILs can be regenerated through a deswelling strategy along with the recycling of the extracted guests.