Constructing CO₂-philic PEG domains on UiO-66-NH₂ via amide tethering for highly efficient CO₂ separation

Abstract

Metal-organic frameworks-based mixed matrix membranes (MMMs) often face a trade-off between interfacial compatibility and intrinsic pore selectivity. Herein, we report a multi-step crosslinking strategy for constructing UiO-66-AC@PEG by covalently bridging MAH-prefunctionalized UiO-66-NH₂ with polyethylene glycol (PEG), enabling simultaneous interfacial engineering and pore regulation. The resulting crosslinked architecture incorporates abundant amide and ether oxygen moieties, which collectively generate CO₂-philic domains and enhance CO₂ sorption through dipole-quadrupole interactions. Meanwhile, MAH-PEG crosslinking induces pore constriction within UiO-66-NH₂, strengthening size-sieving effects toward CO₂/N₂ separation. Moreover, the flexible long-chain architecture of PEG ensures uniform dispersion of UiO-66-AC@PEG within the Pebax matrix. It also effectively suppresses particle agglomeration, thereby minimizing nonselective interfacial defects. Consequently, the optimized UiO-66-AC@PEG/Pebax membrane achieves a CO₂ permeability of 125.8 Barrer and a CO₂/N₂ selectivity of 81.1, corresponding to increases of 56.6% and 33.5%, respectively, compared with the UiO-66-NH₂/Pebax MMM. This work demonstrates that MAH-mediated PEG tethering provides an effective strategy for simultaneously improving CO₂ affinity, diffusion regulation, and filler-polymer interfacial compatibility in MMMs, offering useful guidance for the design of high-performance CO₂ separation membranes.

Graphical abstract

Keywords

Metal-organic frameworks / mixed matrix membranes / CO₂-philic domain / multi-step crosslinking / CO₂ separation

References

[1] Zhang Y , Yin B H , Huang L , Ding L , Lei S . Telfer S, Caro J, Wang H. MOF membranes for gas separations. Progress in Materials Science, 2025, 151: 101432

[2] Qian Q , Asinger P A , Lee M J , Han G , Mizrahi Rodriguez K , Lin S , Benedetti F M , Wu A X , Chi W S , Smith Z P . MOF-based membranes for gas separations. Chemical Reviews, 2020, 120(16): 8161–8266

[3] Shi Y , Wang Z , Shi Y , Zhu S , Lu K , Zhang Y , Jin J . Micrometer-sized MOF particles incorporated mixed-matrix membranes driven by π-π interfacial interactions for improved gas separation. Separation and Purification Technology, 2022, 295: 121258

[4] Radoor S , Mujmule R B , Karayil J , Kim H . Cellulose acetate mixed matrix membranes incorporating APTES-functionalized MOF-5 derived from recycled PET plastic bottles for high-performance gas separation. Journal of Environmental Chemical Engineering, 2025, 13(5): 118914

[5] Wang Z , Sun Y , Qin Z , Yu Q , Zhang Z , Qiao Z . Construction of MOF-based mixed matrix membranes with multiple fluorine sites for low concentration CO₂ separation under humid conditions. Separation and Purification Technology, 2025, 369: 133149

[6] Chen G , Chen C , Guo Y , Chu Z , Pan Y , Liu G , Liu G , Han Y , Jin W , Xu N . Solid-solvent processing of ultrathin, highly loaded mixed-matrix membrane for gas separation. Science, 2023, 381(6664): 1350–1356

[7] Ghalei B , Sakurai K , Kinoshita Y , Wakimoto K , Isfahani Ali P , Song Q , Doitomi K , Furukawa S , Hirao H , Kusuda H . et al. Enhanced selectivity in mixed matrix membranes for CO₂ capture through efficient dispersion of amine-functionalized MOF nanoparticles. Nature Energy, 2017, 2(7): 17086

[8] Refaat D , Yahia M , Martínez-Hernández H D , Jimenez-Ruiz M , Galván V , Petrenko V , Fernández de Luis R , Coronas J . Mixed matrix membranes of PIM-1 incorporating MOF-808 functionalized with amino acids for enhanced CO₂/CH₄ separation. Journal of Materials Chemistry A, 2025, 13(45): 39254–39270

[9] Niu X , Liu Z , Zhao H , Wang J , Dong G , Zhang Y . Engineering homointerface-mediated mixed matrix membrane for propylene/propane separation. AIChE Journal, 2025, 71(5): e18768

[10] Tao Y , Wang L , Li B , Huang J , Pan Y . Engineering gas-permeable MOF/polymer interfaces in mixed-matrix membranes for advanced CO₂ separation. Journal of Membrane Science, 2025, 735: 124588

[11] Zhao T , Jia C , Sun H , Li R , Zhang Z , Wang Y , Guo J , Tian F , Song C . Construction of high-performance mixed matrix membranes with unique gas channels using MIL@ZIF core-shell filler for CO₂ separation. Separation and Purification Technology, 2026, 382: 136067

[12] Ahmadi R , Ebadi Amooghin A , Sanaeepur H . A fine-tuned hollow porous metal-organic framework in mixed-matrix membranes for benchmark CO₂ separation performance. Journal of Materials Chemistry A, 2025, 13(16): 11358–11370

[13] Yin J-K , Zhang C , Ding S-Y , Du H , Tan Z-L , Li M-M , Wang B , Wang T . The strategies to improve the interfacial compatibility in mixed-matrix membranes: a review. Materials Today Energy, 2025, 49: 101811

[14] Zhang D , Zhang Q , Gao N , Yang L , Ma Y , Li H , Zhao Z , Gao J , Li K , Yang S . et al. The interface regulation strategy constructing high performance C₃H₆/C₃H₈ separation membranes via bio-based polyphenols. Chemical Engineering Journal, 2026, 536: 176131

[15] Ma Y , Zhang Y , Liu N , Xu Z , Chu J , Ma X , Meng J . Construction of defect-free MMMs with ultrahigh MOFs loading by a novel “bottom-up” strategy for efficient H₂ separation. Separation and Purification Technology, 2025, 362: 131762

[16] Wang Z , Sun X , Liu Q , Xia C , Yin Q , Liu S , Lu X , Chen H . Amino-ionic liquid-assisted highly compatible mixed matrix membranes of ZIF-8 and PIM-1 for efficient CO₂/N₂ separation. Dalton Transactions, 2025, 54(15): 6281–6289

[17] Radoor S , Karayil J , Kim H . Design of amino acid functionalized ZIF-8/cellulose acetate mixed matrix membranes for improved gas separation efficiency. Sustainable Materials and Technologies, 2025, 46: e01758

[18] Wang H , He S , Qin X , Li C , Li T . Interfacial engineering in metal-organic framework-based mixed matrix membranes using covalently grafted polyimide brushes. Journal of the American Chemical Society, 2018, 140(49): 17203–17210

[19] Zhang K , Huan H , Tian X , Yin C , Ma X , Wang S . MOF gel network crosslinked mixed matrix membranes with engineered interface for high-efficiency helium recovery. Nature Communications, 2026, 17(1): 6159

[20] Su P , Chen S , Chen L , Li W . Constructing polymer/metal-organic framework nanohybrids to design compatible polymer-filler-polymer membranes for CO₂ separation. Journal of Membrane Science, 2024, 691: 122246

[21] Wu S , Shan C , Mo J , Qu J , Liu C , Huang X . Preparation and gas separation performance of ionic liquid modified covalent organic framework/fluorinated polyimide mixed matrix membranes. Journal of Applied Polymer Science, 2026, 143(17): e70563

[22] Sun Y , Gao Y , Geng C , Zhang Z , Qiao Z , Zhong C . Improved CO₂/N₂ separation performance by relatively continuous and defect-free distribution of IL-encapsulated ZIF-67 in ion gel membranes. Journal of Membrane Science, 2023, 683: 121818

[23] Fan Y , Yu H , Xu S , Shen Q , Ye H , Li N . Zn(II)-modified imidazole containing polyimide/ZIF-8 mixed matrix membranes for gas separations. Journal of Membrane Science, 2020, 597: 117775

[24] Bi X , Zhang Y a , Zhang F , Zhang S , Wang Z , Jin J . MOF nanosheet-based mixed matrix membranes with metal-organic coordination interfacial interaction for gas separation. ACS Applied Materials & Interfaces, 2020, 12(43): 49101–49110

[25] Lee T H , Jung J G , Kim Y J , Roh J S , Yoon H W , Ghanem B S , Kim H W , Cho Y H , Pinnau I , Park H B . Defect engineering in metal-organic frameworks towards advanced mixed matrix membranes for efficient propylene/propane separation. Angewandte Chemie International Edition, 2021, 60(23): 13081–13088

[26] Wang Z , Tian Y , Fang W , Shrestha B B , Huang M , Jin J . Constructing strong interfacial interactions under mild conditions in MOF-incorporated mixed matrix membranes for gas separation. ACS Applied Materials & Interfaces, 2021, 13(2): 3166–3174

[27] Mu Q , Sheng L , Chen S , Liu Y , Deng M , Ren J . Thermal induced in-situ defect engineering of ZIF-8 in mixed matrix membranes with significantly enhanced gas separation properties. Separation and Purification Technology, 2025, 360: 131195

[28] Lu Y , Zhang H , Chan J Y , Ou R , Zhu H , Forsyth M , Marijanovic E M , Doherty C M , Marriott P J , Holl M M B . et al. Homochiral MOF-polymer mixed matrix membranes for efficient separation of chiral molecules. Angewandte Chemie International Edition, 2019, 58(47): 16928–16935

[29] Zhang J , Zheng J , Sun X , Wang L , Fan Y , Li S , Xu J , Zhang S . Preparation and properties of mixed matrix membrane based on defective Zr-MOF pore fluorination engineering for gas separation. Journal of Cleaner Production, 2026, 554: 148088

[30] Guo Z , Zheng W , Yan X , Dai Y , Ruan X , Yang X , Li X , Zhang N , He G . Ionic liquid tuning nanocage size of MOFs through a two-step adsorption/infiltration strategy for enhanced gas screening of mixed-matrix membranes. Journal of Membrane Science, 2020, 605: 118101

[31] Niu P , Li T , Zhao Q , Sun Y , Zhang J , Fan F , He G , Ma C . Mixed matrix membranes based on benzimidazole-modulated MOFs for enhanced CO₂ capture and H₂ separation. Industrial & Engineering Chemistry Research, 2025, 64(46): 22363–22374

[32] Strauss I , Chakarova K , Mundstock A , Mihaylov M , Hadjiivanov K , Guschanski N , Caro J . UiO-66 and UiO-66-NH₂ based sensors: dielectric and FTIR investigations on the effect of CO₂ adsorption. Microporous and Mesoporous Materials, 2020, 302: 110227

[33] Liu Q , Zang G-L , Zhao Q . Removal of methyl orange wastewater by Ugi multicomponent reaction functionalized UiO-66-NS. Environmental Science and Pollution Research, 2022, 29(51): 76833–76846

[34] Ajebe E G , Hu C-C , Wang C-F , Hung W-S , Tsai H-C , Hundessa N K , Lee K-R , Lai J-Y . Synergistic effect of combining UiO-66 nanoparticles and MXene nanosheets in Pebax mixed-matrix membranes for CO₂ capture. Materials Today Sustainability, 2024, 26: 100818

[35] Sutrisna P D , Hou J , Zulkifli M Y , Li H , Zhang Y , Liang W , D'Alessandro Deanna M , Chen V . Surface functionalized UiO-66/Pebax-based ultrathin composite hollow fiber gas separation membranes. Journal of Materials Chemistry A, 2018, 6(3): 918–931

[36] Li B , Liu J , He X , Wang R , Tao W , Li Z . Covalent “bridge-crosslinking” strategy constructs facilitated transport mixed matrix membranes for highly-efficient CO₂ separation. Journal of Membrane Science, 2023, 680: 121755

[37] Yuan X , Liu Y , Cao F , Zhang P , Ou J , Tang K . Immobilization of lipase onto metal-organic frameworks for enantioselective hydrolysis and transesterification. AIChE Journal, 2020, 66(9): e16292

[38] Jiang H , Chen M , Jiang X , Song C , Liu Y . Preparation of [C₂mim][BF₄]@ZIF-8/Pebax mixed matrix membranes for enhanced CO₂/N₂ separation performance. Journal of Environmental Chemical Engineering, 2025, 13(4): 117243

[39] Qin Z , Wei J , Hou W , Chen Z , Deng M , Yao L , Sun D , Yang L , Jiang W , Zheng J . et al. Pebax mixed matrix membranes based on novel HOF/MOF nanofiller with simultaneous improvement in CO₂ permeability and CO₂/N₂ selectivity. Journal of Materials Chemistry A, 2025, 13(27): 22020–22030

[40] Feng X , Liu C , Ren K , Zhao X , Liu L , Zhang K , Tian X , Wang Q , Liu X , Yu Y . et al. In-situ synthesis of ZIF-8 gel network in mixed matrix membranes for enhanced CO₂/N₂ separations. Chemical Engineering Science, 2025, 311: 121610

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