Coaxial electrospun nanofibrous substrates with tunable wettability for constructing cucurbit[n]uril-embedded organic solvent nanofiltration membranes

Solvent resistance and high perm-selectivity have always been the pursuit in organic solvent nanofiltration field. Insoluble polyimide nanofibrous membranes feature superior solvent resistance. However, its high hydrophobicity usually limits the uniform spread of the aqueous amine monomers during the interfacial polymerization process, resulting in the non-uniform reaction with the acyl chloride and the defective selective layer. Herein, coaxial electrospinning was employed to construct the core–shell nanofibrous substrates, in which aminated multi-walled carbon nanotubes were added to the shell layer. This strategy endowed the nanofibrous substrates with tunable wettability without sacrificing stability, which guaranteed the one-step construction of defect-free thin-film nanofibrous composite membranes via interfacial polymerization (IP). Further, cucurbit[6]uril was embedded into the polyamide network by coupling host–guest chemistry and IP, providing the wider solvent transport channels and achieving the four times enhanced methanol permeance (22.34 L·m⁻²·h⁻¹·bar⁻¹) without sacrificing the selectivity. The membrane shows application prospects for solvent recovery in chemical, pharmaceutical, and other fields. This work provides new thoughts for the design and modification of novel nanofiltration membranes.