Thermoresponsive Polymer Sorbents for Efficient Removal of Perfluorinated Compounds via Simple Heating

The efficient removal of per- and polyfluoroalkyl substances (PFAS) and recycling sorbents from contaminated water face grand challenges in the field of PFAS remediation. In this work, a series of thermoresponsive perfluoropolyether (PFPE)-containing polymer sorbents were developed for efficient removal of PFAS from contaminated water using a simple heating process. The polymer sorbents are thermoresponsive due to inclusion of the monomer N-isopropylacrylamide (NIPAM). Four block copolymers with the same degree of polymerization (DP) of [2-(acryloyloxy)ethyl]trimethylammonium iodide (AETAI) but increasing DPs of NIPAM were prepared via reversible addition–fragmentation chain-transfer (RAFT) polymerization. The results demonstrate that the balance between hydrophobic/hydrophilic segments from the polymers significantly influences their lower critical transition temperatures (LCSTs), and such balance could be altered by the presence of amphiphilic PFAS. Upon complete sorption, >99% removal for majority of the tested PFAS was achieved by heating the solution mixture to above its lower critical solution temperature and filtration. The study introduces the design and preparation of efficient "smart" PFAS sorbents based on their thermoresponsive properties, offering a new approach to effectively separate PFAS sorbents from treated solutions.