Roll-to-roll fabrication of large-area metal–organic framework-based membranes for high-performance aqueous separations

Metal–organic framework (MOF) membranes have emerged as promising candidates for efficient water purification. However, challenges related to limited spatio-temporal control over metal–ligand interactions and inherent film fragility hinder the scale-up and widespread adoption of MOF-based membranes. Here we report a nanoreactor-confined crystallization strategy that enables rapid and roll-to-roll fabrication of high-performance ultra-thin (∼25 nm) MOF hybrid membranes (0.33 m × 35 m) at mild conditions. This strategy leverages metal-chelated polydopamine nanoparticles as reactors to grow membranes with hierarchical polymer–MOF interconnected structures that promote remarkable stability against chlorine and varying pH levels, precise solute–solute selectivity and high water permeance. The robustness of the resulting membranes facilitates their assembly into spiral-wound membrane modules (0.4 m 2 ) showing excellent and stable (>30-day testing) separation performance in relevant solute–solute separations such as the purification of pharmaceuticals and dye desalination. The nanoreactor-confined crystallization strategy is compatible with a diverse range of MOFs, paving the way for the scalable manufacturing and applications of their membranes.