Soft polymers wet UiO-66 without interfacial voids
MD shows flexible PVDF and PEG fill UiO-66 surface pockets; rigid PIM-1 and PS leave microvoids and fail as 70 wt% films.
Source
Understanding the origins of metal-organic framework/polymer compatibility
Study at a glance
- Design
- Computational / modelling — MD of polymer interfaces on a hydrated UiO-66 slab plus 70–80 wt% mixed-matrix films
- N
- PIM-1, PS, PVDF, and PEG against {101} UiO-66; experimental films at high filler loading
- Population
- MOF/polymer mixed-matrix membrane interfaces
- Outcome
- Flexible PVDF and PEG fill UiO-66 surface pockets; rigid PIM-1 and PS leave microvoids and fail as high-loading films
Structured fields used in claim comparison tables when every cited study has a complete layer.
Inspect source passages
Soft polymers wet UiO-66 without interfacial voids
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
The MOF powder has a BET area of 1380 ± 60 m2 g–1.
yielding 200 nm truncated octahedral particles (Fig. S17) with the expected powder X-ray diffraction pattern (Fig. S18) and a BET area of 1380 ± 60 m 2 g –1 (Table S7, Fig. S19).
z-length A is 15 ± 3 Å for the PIM-1 composite versus 6 ± 1 Å for PVDF.
the affinity of UiO-66 for PVDF (6 ± 1 Å) is higher when compared to PIM-1 (15 ± 3 Å) and PS (9 ± 2 Å), respectively.
What they did
Authors built a hydrated {101} UiO-66 slab, equilibrated PIM-1, PS, PVDF and PEG against it, and made 70–80 wt% PEG MMMs compared with PVDF, PS and PIM-1 films.
What they found
PIM-1/PS interfaces have microvoids (up to 13 Å and 8 Å) and long recovery distances (z-length A 15 and 9 Å). PVDF and PEG show no voids, chain-end pore penetration, and H-bonds at 2.0 vs 1.7 Å. PEG Young's modulus more than doubles at 70 wt% MOF, but N2 area collapses; PVDF keeps MOF porosity.
The limits
What it doesn't show
No gas-separation permeance on the new PEG MMMs; PEG pore blocking is inferred from BET, not in situ pore tomography; only one MOF topology was modelled.
Key terms
- Mixed-matrix membrane (MMM)
- Polymer film filled with MOF particles to combine processability and selectivity.
- z-length A
- Distance from the MOF surface until polymer density recovers its bulk oscillation.
- λs
- Polymer density in the overlap region divided by bulk polymer density.
- UiO-66
- Zirconium terephthalate MOF used here as a 200 nm filler.
- PIM-1
- Polymer of intrinsic microporosity; rigid, poorly packing chains.
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UiO-66 surface cut used in MD:
Common questions
Which polymers are compatible at 70 wt%?
PVDF and PEG form handleable films; PS and PIM-1 crack.
What molecular feature marks compatibility?
No interfacial microvoids and polymer ends in surface pores.
Why does PEG lose BET area?
Stronger OPEG···HOUiO-66 H-bonds compact the interface and block pores.
What Young's modulus cutoff is proposed?
Polymers below ~1 GPa wet the MOF surface.
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