Perfluorooctanoyl chloride engineering toward high-flux antifouling polyamide nanofilms for desalination

Nanofiltration (NF) membranes with high flux and superior antifouling performance are in great demand for water purification. Low-surface-energy fluorine materials have attracted significant attention in the fabrication of antifouling nanofiltration membranes. However, their inferior water affinity usually leads to the sacrifice of membrane water permeability. Herein, we explored perfluorooctanoyl chloride (PFOC) as a reactive additive in the organic phase during support-free interfacial polymerization (IP) to engineer fluorinated polyamide (FPA) nanofilms, which were further transferred onto porous substrates for thin-film composite (TFC) membranes. PFOC can participate in the interfacial polymerization process, leading to an enlarged pore size of the FPA nanofilm. The resultant TFC membrane displayed water permeance of 28.5 ± 0.7 L m−2 h−1 bar−1, about twice as high as that of the pure polyamide (PA) membrane while maintaining Na2SO4 rejection above 98.5% and NaCl rejection below 15.0%. Moreover, the existence of low-surface-energy perfluoroalkyl chains on the FPA nanofilm surface can endow the TFC membrane with superior antifouling properties with a higher flux recovery ratio and lower flux decline ratio against oil/water emulsions (FRR = 97.9%, DRt = 9.5%) and bovine serum albumin (FRR = 98.5%, DRt = 13.9%). Our approach may enlighten a new avenue on engineering high-flux antifouling TFC membranes with fluorine materials.