Membranes Incorporating 2D Single-Crystalline COFs for Superior Separation Performance: 3D Image-Informed Reactive Force Field Modeling and Scalable Mixed-Matrix Systems

Abstract Bridging atomically precise materials design with scalable membrane manufacturing remains a central challenge in separation science. Two-dimensional covalent organic frameworks (2D COFs) offer tunable porosity and chemistry, but poor crystallinity and processability have limited their performance in membranes. Here we demonstrate that incorporating single-crystalline 2D COFs into anodic aluminum oxide supports and scalable mixed-matrix membrane enables exceptional separation performance, achieving ultrahigh permeance (MMM-SC-0.6: 8764 and 4531 L m–2 h–1 bar–1 for hexane and methanol, respectively) and near-quantitative rejection of nanoscale solutes. Reactive force field simulations through a multilayer COF model reveal the origins of rapid solvent transport and size selectivity through steric gating. These results establish highly crystalline COFs as practical, high-performance membrane materials and point to new routes for energy-efficient separations across chemical, environmental, and industrial technologies.