Ultra-thin microporous membranes based on macrocyclic pillar[n]arene for efficient organic solvent nanofiltration

Organic solvent nanofiltration (OSN) is a green, environmentally friendly and sustainable separation technology. High-performance OSN membranes are expected to play a critical role in the field of chemical separation involving organic solvents. However, traditional OSN membranes suffer from the constraints on perm-selectivity. Herein, we introduced macrocyclic molecules with intrinsic angstrom-size cavity, pillar[n]arene (P[n]a, n = 5, 6), as a novel aqueous monomer to react with trimesoyl chloride (TMC) to prepare highly perm-selective thin-film composite (TFC) OSN membranes through interfacial polymerization. The prepared TFC-P[n]a membranes exhibit ultra-thin selective layer thickness of sub-10 nm and possess permanent intrinsic microporous structure, which endows the membrane with high perm-selectivity. Especially, the TFC-P[6]a membrane exhibits a high methanol permeance (8.10 L m−2 h−1 bar−1) and a low molecular weight cut-off (MWCO) of 300 g mol−1. In addition, the prepared TFC-P[n]a membranes exhibit molecule sieving function and could discriminate molecules with similar molecular weights but different shapes. Our work provides an insight of material design for the preparation of next-generation high-performance organic solvent nanofiltration membranes.