Fluoroolefin-vinyl ether copolymer ionic fluorogels for PFAS remediation from water

Abstract

Per- and polyfluoroalkyl substances (PFAS) are a class of toxic chemicals that are ubiquitous in the environment and have contaminated water sources globally. As regulations limiting PFAS concentrations in drinking water are being established by regulatory agencies globally, there is an urgent demand for robust granular sorbents that remove PFAS from water selectively and are easily regenerated. Here we report a new class of Ionic Fluorogels (IF) that leverage fluoroolefin-vinyl ether (FVE) perfectly alternating copolymers as a polymer matrix for the development of ion exchange resins. The use of 2-chloroethyl vinyl ether as a comonomer provided a partially fluorinated polymer with electrophilic functionality, which was reacted with multivalent amines to install covalent crosslinks and cationic character in a single synthetic step. Systematic variation in the identity of fluoroolefin comonomer and multivalent amine resulted in a library of materials for structure–property evaluation. We found that the synergistic combination of a fluorophilic matrix and cationic charge leads to high PFAS sorption, and that the ratio of quaternary ammonium to tertiary amine is an important design criteria. Performance evaluation showed that the FVE-based IFs have high binding capacity for GenX, up to 770 milligrams GenX per gram IF, facile regeneration with no lapse in performance across five cycles, and higher PFAS selectivity than commercial ion exchange resin in both simulated and natural waters.