Fabrication of MMMs with improved gas separation properties using externally-functionalized MOF particles

Mixed matrix membranes (MMM) have the potential to overcome the limitations of traditional polymeric membranes for gas separation by improving both the permeability and selectivity. The most difficult challenge is accessing defect free and optimized MMM membranes. Defects are generally due to incompatible interfaces between the polymer and the filler particle. Herein, we present a new approach to modify and optimize the surface of UiO-66-NH₂ based MOF particles to improve its interaction with Matrimid® polymer. A series of surface modified UiO-66-NH₂ particles were synthesized and characterized using ¹H NMR spectroscopy, mass spectrometry, XPS, and powder X-ray diffraction. MMMs containing surface optimized MOF particles exhibit improved thermal and mechanical properties. Most importantly, the MMMs show significantly enhanced gas separation properties; CO₂ permeability was increased by ∼200% and CO₂/N₂ ideal selectivity was increased by ∼25%. These results confirm the success of the proposed technique to mitigate defective MOF/Matrimid® interfaces.