Aligned macrocycle pores in ultrathin films for accurate molecular sieving

作者：Zhiwei Jiang, Ruijiao Dong, Austin M. Evans, Niklas Biere, Mahmood Abdulsalam Ebrahim, Siyao Li, Dario Anselmetti, William R. Dichtel, Andrew Guy Livingston · 发表于：Nature · 年份：2022 · DOI：10.1038/s41586-022-05032-1 · 被引用次数：338 · 研究领域：Membrane Separation Technologies、Nanopore and Nanochannel Transport Studies、Membrane Separation and Gas Transport

Abstract Polymer membranes are widely used in separation processes including desalination 1 , organic solvent nanofiltration 2,3 and crude oil fractionation 4,5 . Nevertheless, direct evidence of subnanometre pores and a feasible method of manipulating their size is still challenging because of the molecular fluctuations of poorly defined voids in polymers 6 . Macrocycles with intrinsic cavities could potentially tackle this challenge. However, unfunctionalized macrocycles with indistinguishable reactivities tend towards disordered packing in films hundreds of nanometres thick 7–9 , hindering cavity interconnection and formation of through-pores. Here, we synthesized selectively functionalized macrocycles with differentiated reactivities that preferentially aligned to create well-defined pores across an ultrathin nanofilm. The ordered structure was enhanced by reducing the nanofilm thickness down to several nanometres. This orientated architecture enabled direct visualization of subnanometre macrocycle pores in the nanofilm surfaces, with the size tailored to ångström precision by varying the macrocycle identity. Aligned macrocycle membranes provided twice the methanol permeance and higher selectivity compared to disordered counterparts. Used in high-value separations, exemplified here by enriching cannabidiol oil, they achieved one order of magnitude faster ethanol transport and threefold higher enrichment than commercial state-of-the-art membranes. This approach offers a fe...