Fluorinated solvent resistant nanofiltration membrane prepared by alkane / ionic liquid interfacial polymerization with excellent solvent resistance

The preparation of solvent resistant nanofiltration (SRNF) membranes with high permeance and retention is required for accurate chemical separation, yet the solvent resistance of the membranes still needs to be improved. Fluoropolymers with strong weather resistance and chemical stability are expected to improve the solvent resistance of solvent resistant nanofiltration membranes. However, the application of fluorinated monomers in interfacial polymerization has been limited because they are water-insoluble. In this paper, ionic liquids were added to the aqueous phase to improve the solubility of hexafluorobisphenol A (BPAF). Trimesoyl chloride (TMC) was used as organic phase monomer. Fluorinated polyarylester thin film composite (TFC) membranes were synthesized on polyacrylonitrile (PAN) base membranes utilizing interfacial polymerization. The results confirmed that the surface morphology and roughness of TFC membranes could be regulated by adding fluorinated monomer. The membrane sample PAN-F-0.5 exhibits a high permeance for methanol up to 124.05 L m−2 h−1 bar−1. The resulting membrane possesses a molecular weight cut off (MWCO) of∼450 g mol−1. PAN-F-0.5 still showed excellent performance after continuous immersion in DMF for 90 days (room temperature) and 7 days (80 °C), respectively. The results show that the TFC membrane has excellent filtration performance and solvent resistance.