Interfacial Chemistry tunes Performance in a Polysulfone-based MUF-16 Mixed Matrix Membrane for Pre-Combustion CO2-Capture

Mixed matrix membranes (MMMs) are a promising technology for gas separation of different gas mixtures such as H2/CO2; however, their performance is often limited by poor interfacial compatibility between polymer and filler. One effective strategy to overcome this challenge is covalent polymer-filler attachment, which compatibilizes the interface, promotes defect-free membrane formation, and therefore enhances the gas separation properties. However, many existing approaches require MOF pre-treatment or additional synthetic steps, compromising MOF stability, complicating processing and limiting scalability. Herein, we report on a rational polymer design strategy that enables covalent bonding to the MOF directly during membrane fabrication. A chloromethyl-functionalized polysulfone (PSUCH2Cl) is used to form covalent linkages with MUF-16 through a nucleophilic substitution reaction. Successful bonding is directly confirmed by fluorescence, demonstrating that the reaction proceeds in situ during membrane formation without the need for post-modification or filler pre-treatment. This simple, straightforward and efficient approach improved polymer-filler compatibility as observed from SEM micrographs. As a result, the optimized membrane, PSUCH2Cl-MUF-16/DMF (15 wt.%), shows a higher H2/CO2 separation factor of 98 in comparation with the non-optimized PSU-MUF-16/DMF MMM (15 wt.%) with a separation factor of 47.5.