Efficient N2/SF6 separation via intermolecular transient pores in polyaromatic hydrocarbons assembled monolayer prepared by a simple Langmuir–Schaefer approach

Sulfur hexafluoride (SF 6 ) is a widely used insulating gas and a greenhouse gas which requires efficient recycling to minimize its environmental impact. Conventional membrane materials, such as zeolites, polymers, and metal-organic frameworks (MOFs), often suffer from harsh fabrication conditions or insufficient selectivity/permeability. In this work, we present a facile strategy for fabricating a noncovalently bonded polyaromatic hydrocarbon (PAH) monolayer membrane for efficient N 2 /SF 6 separation. The PAH monolayer with a thickness of 1.35 nm was prepared via Langmuir Schaefer (LS) method by using hexa(terpyridine) hexaphenylbenzene (HTPHPB) on air-water interface. Strong π-π stacking interaction between HTPHPB molecules stabilizes the monolayer, while the resulting intermolecular transient nanopores enable selective SF₆ separation from N₂. The resulting 4 layers of HTPHPB membrane, assembled at 25 mN·m −1 , exhibits exceptional SF 6 /N 2 separation performance with a selectivity of 155 ± 4 and a N 2 permeance of 136 ± 4 GPU, overcoming the inherent trade-off between selectivity and permeability in traditional organic membranes. Notably, the membrane maintains its separation performance even under bending, demonstrating excellent mechanical flexibility. This study offers a tunable and scalable organic membrane design strategy, paving the way for industrial applications in SF 6 recovery and gas separation.