SOLID STATE NMR INVESTIGATION OF MIXED MATRIX MEMBRANES BASED ON FUORINATED METAL-ORGANIC FRAMEWORKS

Mixed matrix membranes (MMMs) are emerging as a promising technology for gas separation. These materials are composites made by blending a polymer with a porous filler that exhibits exceptional adsorption properties, such as a covalent organic framework or a metal-organic framework (MOF). Due to their composition, MMMs are considered next-generation membranes, since they combine the processability advantages of the polymer with the enhanced separation properties of the filler.[1] Understanding the separation properties of the composites requires characterizing the structural and dynamic properties of both filler and membrane at the atomic level, as well as understanding how they are altered in the composite. This knowledge is crucial for the design of novel materials with improved separation properties. Solid State NMR (SSNMR) is widely recognized as one of the most powerful techniques for characterizing the structural and dynamic properties of MOFs, composite materials, and their adsorbates at the atomic scale.[2,3] This is primarily due to the possibility to detect different nuclear observables (chemical shifts and anisotropic line shapes, dipolar couplings, nuclear relaxation times, etc.) that are highly sensitive to local structure and dynamics. In this study, multinuclear SSNMR is used to investigate three different perfluorinated MOFs with high affinity for CO2,[4,5,6] gas separation membranes obtained from the commercial polymer Hyflon, and their corresponding MMMs. 13C, 19F and 1H high-resolution SSNMR spectra and longitudinal relaxation times are analyzed to unravel structural and dynamic properties of the MOFs and the membrane and how they change in the MMMs. Acknowledgements The authors thank the Italian Ministry of University and Research through the Project PRIN 2020 doMino (ref. 2020P9KBKZ) References [1] J. Dechnik, et al. Angew. Chem. Int Ed. 2017, 56, 9292-9310. [2] B. E. G. Lucier, S. Chen, Y. Huang Acc. Chem. Res. 2018, 51, 319-330. [3] B. Reif, et al. Nat. Rev. Methods Primers 2021, 1, 2. [4] R. D'Amato, et al. ACS Sustainable Chem. Eng. 2019, 7, 394-402. [5] M. Cavallo, et al. J. Mater. Chem. A. 2023, 11, 5568-5583. [6] D. Morelli Venturi, et al. Mol. Syst. Des. Eng., 2023,8, 586-590