Assembling covalent organic framework membranes via phase switching for ultrafast molecular transport




Khan, Niaz Ali
Zhang, Runnan
Wang, Xiaoyao
Cao, Li
Azad, Dr Chandra Sourabh
Fan, Chunyang
Yuan, Jinqiu
Long, Mengying
Wu, Hong
Olson, Mark

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Fabrication of covalent organic framework (COF) membranes for molecular transport has excited highly pragmatic interest as a low energy and cost-effective route for molecular separations. However, currently, most COF membranes are assembled via a one-step pro cedure in liquid phase(s) by concurrent polymerization and crystallization, which are often accompanied by a loosely packed and less ordered structure. Herein, we propose a two-step procedure via a phase switching strategy, which decouples the polymerization process and the crystallization process to assemble compact and highly crystalline COF membranes. In the pre-assembly step, the mixed monomer solution is casted into a pristine membrane in the liquid phase, along with the completion of polymerization process. In the assembly step, the pristine membrane is transformed into a COF membrane in the vapour phase of solvent and catalyst, along with the completion of crystallization process. Owing to the compact and highly crystalline structure, the resultant COF membranes exhibit an unprecedented per meance (water ≈ 403 L m−2 bar−1 h−1 and acetonitrile ≈ 519 L m−2 bar−1 h−1 ). Our two-step procedure via phase switching strategy can open up a new avenue to the fabrication of advanced organic crystalline microporous membranes.



membranes, molecular transport, organic framework, phase switching


This project was supported by Key Research and Development Program of Zhejiang Province, grant No. 2021C03173 (Z. J.), National Natural Science Foundation of China, grant No. 91934302 (Z. J.), 21961142013 (Z. J.), 22008172 (R. Z.), Research Fund for International Young Scientists funded by NSFC, grant No. 21850410457 (N. A. K.), Project funded by China Postdoctoral Science Foundation, grant No. 2020TQ0226 (R. Z.), 2021M692384 (R. Z.), and Program of Introducing Talents of Discipline to Universities, grant No. BP0618007 (Z. J.). We also thank the Haihe Laboratory of Sustainable Chemical Transformations for financial support. We acknowledge the help of Y. Chao during figures drawing.


Attribution 4.0 International


Khan, N.A., Zhang, R., Wang, X. et al. Assembling covalent organic framework membranes via phase switching for ultrafast molecular transport. Nat Commun 13, 3169 (2022).