Superhigh CO2-Permeable Mixed Matrix Membranes Composed of a Polymer of Intrinsic Microporosity (PIM-1) and Surface-Modified Silica Nanoparticles

Polymer gas separation membranes, especially the mixed matrix membranes (MMMs) that consist of polymer matrix and additives, find important applications in carbon dioxide (CO 2 ) separation or capture. Here we show the CO 2 permeation properties of MMMs composed of a polymer of intrinsic microporosity (PIM-1) and nonporous silica nanoparticles modified with various organic moieties including terephthalic acid (TPA), 3,5-diaminobenzoic acid (DABA), and 3,5-dimethylbenzoic acid (DMBA). The MMM with a loading of 25 wt % DMBA-modified nanoparticles indicated outstanding CO 2 permeability (7930 Barrer), which was more than 6 times higher than the original PIM-1 membrane (1250 Barrer), with only a 15% decrease in CO 2 /N 2 selectivity (19.8 for PIM-1 membrane and 16.8 for the MMM). Physical aging in the PIM-1 membrane is well-known to reduce CO 2 permeability in the short term significantly and limits the application to CO 2 separation or capture; however, it was clear that the MMMs containing the DMBA-modified nanoparticles maintained the enhanced CO 2 permeability without a decline in CO 2 /N 2 selectivity after storing under ambient conditions for 60 days.