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DOE OSTI · 2511333

CO 2 in Ionene–Ionic Liquid Composite Membranes

Chen, Ying [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA] (ORCID:0000000174170991)·Nguyen, Manh‐Thuong [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA]·Yao, Jennifer [Pacific Northwest National Laboratory Energy and Environment Directorate Richland WA 99352 USA]·Han, Kee Sung [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA]·Ravula, Sudhir [Department of Chemical &amp, Biological Engineering University of Alabama Tuscaloosa AL 35487‐0203 USA]·Zhang, Mingyi [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA]·Xia, Ying [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA]·Walter, Eric D. [Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory Richland WA 99352 USA]·Bazak, J. David [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA]·Young, Robert P. [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA]·Zhu, Zihua [Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory Richland WA 99352 USA]·Bara, Jason E. [Department of Chemical &amp, Biological Engineering University of Alabama Tuscaloosa AL 35487‐0203 USA]·Washton, Nancy M. [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA]·Heldebrant, David J. [Pacific Northwest National Laboratory Energy and Environment Directorate Richland WA 99352 USA, Department of Chemical Engineering Washington State University Pullman WA 99164 USA]
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Abstract

Abstract Ionene – ionic liquid (IL) composites are promising materials for CO 2 separation, yet a molecular‐level understanding of their structure and its impact on CO 2 speciation, solubility, rotation, and diffusivity remains unclear. Herein, using multimodal nuclear magnetic resonance (NMR), time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS), atomic force microscopy (AFM), and molecular dynamics (MD) simulations, we reveal that the composites contain IL‐rich domains extending across hundreds of nanometres within the ionene matrix, and these bicontinuous domains span the entire membrane depth. CO 2 also absorbs into the ionene matrix, with the distribution between two CO 2 species varying with temperature and time. The rotational correlation times of these two species are on the timescale of 0.1 and 1 ns, respectively. As IL content increases, the ionic domains expand, resulting in higher CO 2 solubility due to enhanced molecular dynamics and increased free volume in both ionene backbones and IL‐rich regions. Although CO 2 diffusion in the membranes is an order of magnitude slower than in bulk IL, the activation energy for CO 2 diffusion remains comparable. Ionene‐IL composites represent a promising platform for designing CO 2 separation membranes, offering enhanced CO 2 diffusion and selectivity through IL‐rich domains, and increased CO 2 solubility and mechanical integrity from the ionene matrix.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRYCO2 diffusionCO2 separationNMRionene-ionic liquid (IL) compositesrotational correlation times

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Chen, Ying [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA] (ORCID:0000000174170991), Nguyen, Manh‐Thuong [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA], Yao, Jennifer [Pacific Northwest National Laboratory Energy and Environment Directorate Richland WA 99352 USA], Han, Kee Sung [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA], Ravula, Sudhir [Department of Chemical &amp, Biological Engineering University of Alabama Tuscaloosa AL 35487‐0203 USA], Zhang, Mingyi [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA], Xia, Ying [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA], Walter, Eric D. [Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory Richland WA 99352 USA], Bazak, J. David [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA], Young, Robert P. [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA], Zhu, Zihua [Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory Richland WA 99352 USA], Bara, Jason E. [Department of Chemical &amp, Biological Engineering University of Alabama Tuscaloosa AL 35487‐0203 USA], Washton, Nancy M. [Pacific Northwest National Laboratory Physical and Computational Sciences Directorate Richland WA 99352 USA], Heldebrant, David J. [Pacific Northwest National Laboratory Energy and Environment Directorate Richland WA 99352 USA, Department of Chemical Engineering Washington State University Pullman WA 99164 USA]. 2025-02-04. CO 2 in Ionene–Ionic Liquid Composite Membranes. https://doi.org/10.1002/adsu.202400802

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