Conferring efficient alcohol dehydration to covalent organic framework membranes via post-synthetic linker exchange

Covalent organic frameworks (COFs) have gained tremendous interest as membrane building blocks owing to rigid, long-range ordered and easily functionalized skeletons. The facile, controllable and task-specific construction of COF membranes lies in the frontier of membrane technology. Herein, we explored a post-synthetic linker exchange (PLE) method to engineer COF membranes for efficient alcohol dehydration. The proposed PLE method, utilizing the reversible breaking-reformation basis between pristine COF membranes and post-introduced linkers, narrowed the effective pore size to intensify molecular sieving property. Moreover, the PLE method also endowed COF membranes with more hydrophilic groups, thus improving the water sorption ability of COF membranes. The resultant COF membranes exhibited superior n-butanol dehydration performances with 3620 of selectivity, 11.35 kg m−2 h−1 of total flux and remained stable in 15-day operation. This PLE method may flourish the library of engineering COF membranes for efficient molecular separations.