Hierarchical Porous Polymers via a Microgel Intermediate: Green Synthesis and Applications toward the Removal of Pollutants

Exploring a synthetic approach to prepare processable hierarchical porous polymers (PPs) is challenging. In the article, a strategic approach is presented, where polymerization (hyperbranching)-induced self-assembly in water leads to the formation of porous microgels (containing both micropores and mesopores), which is followed by spontaneous cross-linking of those intermediate microgels, leading to the formation of PPs. The synthetic process involves simple and green reactions. During this process, hydrophobicity of chosen monomers controls the morphology and porosity of the microgel, which in turn dictates the hierarchical porous morphology of the PPs. Such a synthetic hierarchy during the PP formation in water ensures increase of both surface area and active functionalities among different prototypes. Furthermore, under right conditions, the microgel-based emulsion can be used to form homogeneous porous thin films (average thickness 2–10 nm), which is important in the context of processability of such polymers. The synthesized hierarchical PPs have excellent adsorption capacities for different pollutants, such as iodine (3020 mg/g), methyl orange (1571 mg/g), congo red (1125 mg/g), and high CO₂ uptake capacity with good selectivity.