Fluorous microgel star polymers: selective recognition and separation of polyfluorinated surfactants and compounds in water.

Immiscible with either hydrophobic or hydrophilic solvents, polyfluorinated compounds (PFCs) are generally "fluorous", some of which have widely been employed as surfactants and water/oil repellents. Given the prevailing concern about the environmental pollution and the biocontamination by PFCs, their efficient removal and recycle from industrial wastewater and products are critically required. This paper demonstrates that fluorous-core star polymers consisting of a polyfluorinated microgel core and hydrophilic PEG-functionalized arms efficiently and selectively capture PFCs in water into the cores by fluorous interaction. For example, with over 10 000 fluorine atoms in the core and approximately 100 hydrophilic arms, the fluorous stars remove perfluorooctanoic acid (PFOA) and related PFCs in water from 10 ppm to as low as a parts per billion (ppb) level, or an over 98% removal. Dually functionalized microgel-core star polymers with perfluorinated alkanes and additional amino (or ammonium) groups cooperatively recognize PFOA or its ammonium salt and, in addition, release the guests upon external stimuli. The "smart" performance shows that the fluorous-core star polymers are promising PFC separation, recovery, and recycle materials for water purification toward sustainable society.