Mixed Matrix Membranes from a Microporous Polymer Blend and Nanosized Metal–Organic Frameworks with Exceptional CO₂/N₂ Separation Performance

Most examples of mixed-matrix membranes (MMMs) involve one type of polymer and one type of inorganic filler particle. Here, both polymer blending and MMM approaches are combined to form exceptional three-component membranes for CO2/N2 separation. Nano-sized amino-functionalized UiO-66 is added to a polymer blend of PIM-1 and an ether side chain functionalized polyphosphazene (MEEP80) to create a series of MMMs. Incorporation of UiO-66-NH2 particles boosts the CO2 permeability of the PIM-1/MEEP80 (75:25) blend from 3140 up to nearly 6000 Barrer, while maintaining its CO2/N2 selectivity within the range of 22–25, placing it well above the 2008 Robeson upper bound. In addition, the compatibility of the component parts leads to improved mechanical flexibility and mitigated physical aging for more than 300 days. This unique strategy constitutes a facile MMM formulation approach for energy efficient carbon capture from flue gas.