Swelling and organic solvent nanofiltration in polyimides of intrinsic microporosity membranes: Molecular simulation investigation

KY Zhang and YF Guo and JW Jiang, JOURNAL OF MEMBRANE SCIENCE, 735, 124575 (2025).

DOI: 10.1016/j.memsci.2025.124575

As a unique class of microporous polymers, polyimides of intrinsic microporosity (PIM-PIs) have received significant attention for organic solvent nanofiltration (OSN). This work employs molecular simulations to examine the swelling behavior and OSN performance of nine newly designed PIM-PI membranes in methanol. The swelling degree is found to quantitatively correlate with both pore size and membrane-solvent interaction. The membranes composed of bulkier triptycene-based units demonstrate a larger decrease in bulk density and a more pronounced change in pore morphology after swelling, indicating a higher swelling degree. The hydrogen-bonds of methanol molecules are revealed to possess a longer lifetime in the membranes than in a bulk phase, due to the constraint and interaction by polymer matrix. Three out of nine membranes are computationally predicted to possess methanol permeabilities higher than many existing membranes reported in literature. The microscopic insights from this study would facilitate the rational design of new high-performance OSN membranes.

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