Powder-to-membrane transformation affording 2D/3D COF membranes for molecular separations

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The rapid advancement of reticular chemistry has enabled the synthesis of thousands of covalent organic framework (COF) powders bearing various structures and functions. Nevertheless, processing these COF powders into application-ready membranes with precise separation capacity remains a formidable challenge. Herein, a dynamic covalent chemistry-based dual-drive strategy is harnessed to drive macroscopic structural variation, achieving the transformation of powdered COFs into defect-free COF membranes. This powder-to-membrane transformation is enabled by the internal factor of framework reconstruction and the external driving force of acid attack, showcasing high processibility, which affords scalable two-dimensional (2D) and three-dimensional (3D) COF membranes with a maximum area of 225 cm2. The optimum TpPa membrane demonstrates excellent performance in molecular sieving, displaying high rejections towards dye (99%) and pharmaceutical molecules (98%) and a pure water permeance of 179.0 L m−2 h−1 bar−1. Moreover, our dual-drive transformation outperforms conventional methods in fabrication efficiency, conversion ratio, separation performance, etc., offering a green, efficient, versatile, and scalable strategy for the preparation and application of COF membranes in chemical engineering separations. Processing covalent organic framework (COF) powders into application-ready membranes with precise separation capacity remains challenging. Here, the authors demonstrate a dual-drive strategy that drives macroscopic structural variation and transforms COF powders into defect-free membranes.