Cucurbit[6]uril-regulated polyamide thin-film composite membranes for organic solvent nanofiltration

The simultaneous optimization of permeability and selectivity remains a cardinal challenge in advancing organic solvent nanofiltration (OSN). However, conventional OSN membranes are fundamentally constrained by the “trade-off” problem between permeability and selectivity. To break this limitation, we successfully prepared polyamide thin-film composite (PA-TFC) OSN membranes with both high permeability and high selectivity by incorporating cucurbit[6]uril (CB[6]) into the PA layer. The water insolubility of CB[6] was addressed through complexation with polyethyleneimine (PEI). The successful complexation of CB[6] was verified using techniques such as Ultraviolet-visible spectrophotometer (UV–Vis), Field emission scanning electron microscope (FE-SEM), and other testing approaches. The impact of CB[6] on the chemical composition and surface morphology of the PA layer was also systematically analyzed. In addition, we investigated the effects of monomer concentration on the membrane of permeability-selectivity performance. Experimental results show that the modified membrane, by building the solvent transport channels, showed significantly enhanced methanol permeability (increased by 164 %, 3.19 vs 1.21 L·m -2 ·h -1 ·bar -1 ), while preserving the satisfactory rejection capacity for small molecules (390 Da) (>90 %). Based on the physical parameters of different solvents, we further analyzed the solvent transport mechanism of the prepared OSN membrane. This study provides new insights and approaches for the design of high performance nanofiltration membranes with the aid of macrocycles.