Microstructure engineering of polyamide membranes for ultrafast polar and non-polar solvent transport

Abstract

Highly permselective membranes with superior permeability and broad applicability are essential for organic solvent nanofiltration (OSN). However, conventional polyamide membranes often suffer from limited permeability, especially for non-polar solvents. We herein propose a simple yet effective strategy to fabricate polyamide membranes capable of ultrafast separation for both polar and non-polar solvents. By utilizing a non-planar amine monomer with diphenyl ether moiety, interfacial polymerization is rationally conducted at the deep eutectic solvent/alkane interface, yielding an ultrathin polyamide layer (~12 nm) with enhanced microporosity, uniform nanopores and a Janus-like microstructure. The resultant membrane demonstrates high permeability (36.6 L m⁻² h⁻¹ bar⁻¹ for methanol, 56.6 L m⁻² h⁻¹ bar⁻¹ for hexane), precise molecular sieving capability and excellent structural stability. The work provides a paradigm for developing high-performance OSN membranes through the molecular-level design and powerful control of the manufacturing process.