Interfacial Synthesis of Free‐Standing Metal–Organic Framework Membranes
Bibliographic record
Abstract
Abstract A method based on a liquid–liquid interfacial coordination mechanism has been developed for the synthesis of free‐standing metal–organic framework (MOF) membranes. MOF precursors, zinc nitrate [Zn(NO3)2] and terephthalic acid (TPA or H2BDC), as well as catalyst triethylamine (TEA), were dissolved in two immiscible solvents, dimethylformamide (DMF) and hexane. The reaction of Zn(NO3)2 and TPA (at a 2:1 molar ratio) in DMF was catalyzed by TEA in hexane at the solvent interface thus forming a free‐standing membrane. A region of reactant concentrations critical to membrane formation was identified; a free‐standing membrane could only be formed in the region of high Zn/TPA and low TEA concentrations. The combination of low Zn/TPA and high TEA concentrations yielded MOF particles that precipitated from DMF. The membranes were characterized by SEM and XRD and found to be asymmetric. SEM results showed that the top layer was particulate, whereas the bottom layer had a sheet‐like morphology, which was further revealed by XRD data as 3D Zn4O(BDC)3 (also known as MOF‐5) and 2D ZnBDC·DMF (MOF‐2) for the top and bottom, respectively. Other transitional zinc–carboxylate structures between the two MOFs, namely Zn3(OH)2(BDC)2 (MOF‐69c) and Zn5(OH)4(BDC)3, were also observed with small signal intensities revealing a transition of coordination modes between zinc ions and BDC groups from 3D to 2D at the membrane cross‐section. This was caused by a change of the TEA diffusion rate during the synthesis process, which might change the pH and alter the membrane growth. From both SEM and XRD characterizations, MOF‐2 is the dominant material in the overall composition. Nitrogen adsorption tests showed an average Langmuir surface area of 709 m2/g for the membrane, demonstrating its potential for gas separation applications.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".