Mitigated Aging in a Defective Metal–Organic Framework Pillared Polymer of an Intrinsic Porosity Hybrid Membrane for Efficient Gas Separation

Although polymers of intrinsic microporosity (PIMs) have been recognized as highly permeable membrane materials in gas separation, the physical aging phenomenon seriously affected their performance due to the collapse of micropores. In this work, we report an alternative approach to alleviate the physical aging of PIM-based membranes, as demonstrated by pillaring the PIM-1 membrane with defect-engineered metal–organic framework (MOF) nanoparticles. With excellent interfacial compatibility between the defective UiO-66-FA and PIM-1 by the formation of hydrogen-bond networks, the incorporated MOF nanoparticles acted as pillars of the resulting mixed matrix membranes (UiO-66-FA/PIM-1 MMM) to prevent the collapse of the micropores of the PIM-1 membrane and hence reduce its aging. Concurrently, defective MOFs in the polymer matrix endow the resulting MMMs with fast diffusion pathways and facilitate CO2 transport. Compared with the pristine PIM-1 membrane, UiO-66-FA/PIM-1 MMM displayed maintained CO2/N2 selectivity of about 23.1 but a sharp increased CO2 permeability from 3980 to 16,591 barrer. Only a 25% reduction in CO2 permeability was observed for the UiO-66-FA/PIM-1 MMM after 160 days of operation under the mixed-gas CO2/N2 separation conditions, which is less than the equivalent losses of 40 and 76% for the counterpart MOF-based hybrid membrane and PIM-1, respectively. Given that the performances of the resulting membranes far surpass the 2008 Robeson upper bound, this study may provide a feasible way for sustainable development of PIM-based MMMs in gas separation application.