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Ultra-rapid preparation of large-area high-crystallinity covalent organic framework membranes
Summary:
The authors from Xinjiang University, Beijing University of Technology, Shanghai Jiao Tong University and University of North Texas developed a 0.4×1.0 m, 115 nm-thick C8-IL-TbPa-COF membrane via reverse-phase microemulsion interfacial polymerization, achieving 111.3 L m⁻² h⁻¹ bar⁻¹ water flux and 98 % protein desalination in bioprocessing.
Background:
1. To address the long crystallization time (minutes–days) and poor scalability of high-crystallinity COF membranes, previous researchers used catalysis, solvent tuning or electrophoresis, yet large-area second-scale synthesis remains elusive.
2. The authors propose an ionic-liquid/acetic-acid reverse microemulsion that pre-orders Tb monomers and in-situ encapsulates water, accomplishing simultaneous polymerization–crystallization within 30 s.
Research Content:
1. Synthesis: Tb (0.7 wt %) in C8-IL ([C8MIm][NTf₂]) was interfaced with 60 wt % AcOH aqueous containing Pa (2 wt %); scraping-assisted coating at 80 mm s⁻¹ delivered meter-scale composite on PAN support.
2. Characterizations:
1) BET 379 m² g⁻¹, pore size 1.4 nm;
2) SEM/TEM show 0.35 nm lattice fringes, (001) preferred orientation;
3) GIWAXS, WAXS, FT-IR, XPS, RDF and MD confirm ion-HB pre-ordering and water nanocluster encapsulation.
3. Application: Nanofiltration gives 99.4 % rejection to Evans Blue (MW 960 Da) and 98 % salt removal from 66.3 kDa collagen solution over 6 cycles, outperforming commercial US020 (82 %).
4. Mechanism: IL hydrogen-bond network lowers crystallization barrier; AcOH-triggered reverse microemulsion rapidly removes water, synergistically accelerating Schiff-base kinetics (binding energy −95.2 kJ mol⁻¹).
Outlook:
The work breaks the “slow-crystallization” dogma for COF membranes, offering a scalable, room-temperature route for precision molecular separations in biopharma and water treatment.
Ultra-rapid preparation of large-area high-crystallinity covalent organic framework membranes
Authors: Yan Pan, Gangqiang Yu, Luteng Gao, Xueyong Li, Lan Yang, Haiqi Gao, Tianfu Wang, Wenhai Zhang, Shengqian Ma, Hong Meng
DOI: 10.1038/s41467-025-67569-9
Link: https://doi.org/10.1038/s41467-025-67569-9
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