Mixed-Matrix Membranes with Covalent Triazine Framework Fillers in Polymers of Intrinsic Microporosity for CO2 Separations

Polymers of intrinsic microporosity (PIMs) exhibit high permeability but moderate selectivity, which limits their industrial application in membrane gas separations. Here, a novel CO2-philic perfluorinated covalent triazine framework (FCTF-1) filler in a PIM-1 matrix is utilized to enhance gas selectivity and permeability simultaneously. The predominately organic nature of FCTF-1 improves interfacial compatibility with the polymer matrix. The presence of polar functionality, i.e., triazine rings and fluorine atoms, leads to the preferential sorption of CO2 over CH4, thus increasing solubility selectivity, while the microporosity of FCTF-1 increases diffusion selectivity. PIM-1@FCTF-1 mixed matrix membranes (MMMs) with 2 wt % filler loading exhibited a CO2 permeability of 7300 barrer and a CO2/CH4 selectivity of 16.6. In addition, we report some initial mixed gas propene/propane separation data to determine the applicability of PIM-1@FCTF-1 MMMs to other small molecule separations. This work provides a potential approach to fabricating PIM-1-based MMMs with covalent triazine framework (CTF)-type fillers for gas separation.