Confined In Situ Synthesis of Uniformly Distributed Mixed Matrix Membranes via Solvent Evaporation for Efficient CO2 Capture

The fabrication of polymers of intrinsic microporosity (PIMs)-based mixed matrix membranes (MMMs) is an effective strategy to combine the superior selectivity of porous nanofillers and the high gas permeability of PIMs, which is expected to be a new generation of membrane for efficient CO2 capture. However, the aggregation and sedimentation of the nanofillers along with their insufficient interfacial compatibility with PIMs matrix often result in uncontrollable defects and non-selective voids among the polymer matrix, which seriously deteriorate the anticipated gas separation performance. For the first time, this work proposes a "solvent-evaporation-induced-confinement" strategy for in situ growth of zeolitic imidazole framework-90 (ZIF-90) nanofillers throughout amidoxime-functionalized PIM-1 (AOPIM-1) matrix. The defect-free microporous membrane exhibits a uniform distribution of highly loaded nanofillers with excellent PIMs-MOF interfacial compatibility. The optimized AOPIM-1/ZIF-90 (AO/ZIF) MMM exhibits an exceptional CO2 separation performance with the CO2/N2 and CO2/CH4 selectivity of 42.08 and 71.25, respectively, and a CO2 gas permeability of 1719.1 Barrer. In addition, in situ preparation of ZIF-8 and ZIF-67 nanofillers among the AOPIM-1 matrix further confirms the versatility of the proposed "solvent-evaporation-induced-confinement" strategy. The proposed strategy presents a versatile approach to achieve tunable growth of MOF nanofillers for the preparation of high-performance PIMs-based MMMs for carbon capture.