摘要
Carbon molecular sieve (CMS) membranes have attracted increasing attention for gas separation owing to their superior thermal and chemical stability; however, the intrinsic permeability–selectivity trade-off, mainly caused by insufficient control of ultramicropore evolution during carbonization, remains a critical challenge. In this work, a synergistic ultramicropore engineering strategy is developed by incorporating imidazolium-based ionic liquids (ILs) into γ-cyclodextrin (γ-CD) modified polyimide (PI) precursors to precisely regulate carbon microstructure formation. The rigid γ-CD units function as cavity-size-directing porogens to induce hierarchical microporous structures, while ILs act as structure-directing additives that modify the local free-volume environment and regulate carbon framework rearrangement during pyrolysis, enabling precise modulation of ultramicropore size and evolution. As a result, the CMS membranes exhibit exceptionally high gas permeability combined with markedly enhanced diffusion selectivity. The optimized membranes achieve CO 2 and H 2 permeabilities exceeding 2.1×10 4 and 2.4×10 4 Barrer, respectively, together with CO 2 /CH 4 and H 2 /CH 4 selectivities of 55.1 and 71.3, surpassing the Robeson upper bounds for multiple gas pairs. Structural characterization and gas transport analysis demonstrate that the superior separation performance originates from IL-mediated regulation of ultramicropore size distribution and pore connectivity. This work highlights the multifunctional role of ionic liquids in directing pore evolution and provides a versatile, molecular-level design strategy for next-generation high-performance CMS membranes. A γ-CD and IL regulated PI precursor enables an ultrapermeable CMS membrane with controlled ultramicropore evolution for efficient gas separation. Download: Download high-res image (120KB) Download: Download full-size image
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