Covalent Organic Framework Membranes for Enhanced Gas Dissolution in Oxygenation

Membrane-mediated gas-to-liquid mass transfer is crucial for chemical reactions and biological processes, yet low gas solubility in water limits exchange efficiency. To address this challenge, we leverage periodic, hydrophilic gradient nanochannels in highly oriented covalent organic framework (COF) membranes. These membranes exhibit a significantly higher oxygen dissolution rate than macroporous membranes with greater gas permeability, driven by nanoconfinement effects and increased liquid meniscus curvature, which reduce the hydrogen bond density and lower the oxygen–water binding energy. The engineered COF membrane achieves an unprecedented O₂ transfer rate of 2838 mL m^–2 min^–1 to blood, 11 times higher than that of the conventional oxygenation membrane, poly(4-methyl-1-pentene), while offering comparable blood compatibility and anticoagulant properties, along with a reduced risk of gas embolism.