Marangoni-driven assembly of HOF-PDMS composite membranes with enhanced CO2/O2 separation performance

Oxygenation membranes for extracorporeal membrane oxygenation systems require ultrathin, defect-free selective layers that simultaneously deliver high gas permeability, selectivity, and operational stability. Herein, we report a Janus composite membrane featuring a dense polydimethylsiloxane (PDMS) selective layer integrated with a hydrogen-bonded organic framework (HOF-TGU-307), designed to overcome filler aggregation and transport limitations commonly encountered in ultrathin mixed-matrix membranes. A Marangoni convection-driven assembly strategy induces strong in-plane flow at the gas–liquid-solid interface, enabling uniform dispersion and horizontal embedding of HOF crystallites within the PDMS matrix. Theoretical analysis and molecular dynamics simulations confirm that Marangoni flow suppresses capillary-driven aggregation, while a stable PDMS-HOF interfacial network forms polar gas-transport pathways and promotes interfacial CO 2 enrichment. As a result, the optimized M3-HOF membrane exhibits a high single-gas CO 2 permeance of 1883 GPU and an ideal CO 2 /O 2 selectivity of 5.2, measured at 0.1 MPa and 25 °C, together with an oxygen transfer rate of 219.8 mL·min −1 ·m −2 . The Janus architecture further provides excellent interfacial stability, effectively preventing liquid penetration (LEP > 0.6 MPa). Auxiliary evaluations demonstrate reduced protein adsorption and favorable blood-contacting compatibility, supporting its potential for membrane oxygenators. This computation-guided, Marangoni-driven fabrication strategy offers a scalable route for constructing high-performance oxygenation membrane with controlled ultrathin selective layers.