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

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.