Polymer Infiltration into Metal-organic Frameworks in Mixed-Matrix

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Polymer Infiltration into Metal-organic Frameworks in Mixed-Matrix Membranes Detected In Situ by NMR Pu Duan, Jessica C. Moreton, Sérgio R. Tavares, Rocio Semino, Guillaume Maurin, Seth M. Cohen, and Klaus Schmidt-Rohr J. Am. Chem. Soc., Just Accepted Manuscript • Publication Date (Web): 11 Apr 2019 Downloaded from http://pubs.acs.org on April 11, 2019

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Journal of the American Chemical Society

Polymer Infiltration into Metal-organic Frameworks in MixedMatrix Membranes Detected In Situ by NMR Pu Duan1†, Jessica C. Moreton2†, Sergio R. Tavares3, Rocio Semino3, Guillaume Maurin3*, Seth M. Cohen2*, and Klaus Schmidt-Rohr1* 1

Department of Chemistry, Brandeis University, Waltham, Massachusetts, 02453, USA Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, 92093, USA 3 Institut Charles Gerhardt Montpellier UMR 5253 CNRS, Université de Montpellier, Place E. Bataillon, 34095 Montpellier Cedex 05, France 2

†

These authors contributed equally to this research

Supporting Information Placeholder ABSTRACT: Solid-state NMR has been used to study mixed-matrix membranes (MMMs) prepared with a metal-organic frame-

work (UiO-66) and two different polymers (PEO and PVDF). 13C and 1H NMR data provide overwhelming evidence that most UiO-66 organic linkers are within 1 nm of PEO, which indicates that PEO is homogeneously distributed throughout the MOF. Systematic changes in MOF 13C NMR peak positions and 1H NMR line widths, as well as dramatic reductions in the MOF 1H T1ρ relaxation times are observed as the PEO content increases, and when the pores have been filled, a further increase in PEO results in formation of semicrystalline PEO outside the UiO-66 particles. In contrast, similar studies on PVDF MMMs show that the polymer only contacts a small fraction (20,000 repeat units) can infiltrate and fully occupy the pores of UiO66 particles in MMMs (blocking the porosity and surface area of the MOF), while another membrane-forming polymer, poly(vinylidene fluoride) (PVDF), shows much more limited infiltration into the MOF, leaving substantial MOF porosity intact. The NMR observations are consistent with MOF surface area measurements, polymer crystallinity observed by DSC, and MD simulations. These findings provide a new tool to study and define MOF–polymer interactions within freestanding MMM materials.

METHODS SECTION MOFs and MMMs. MOF MMMs were fabricated as previ23-25 Small particles of UiO-66(Zr)25 were susously reported. pended in acetone via sonication, then mixed into an appropriate amount of polymer solution and concentrated to a viscous ‘ink’ by rotary evaporation. This ‘ink’ was then cast onto an Al-foil substrate and dried at 70°C for one hour, then peeled off the backing with tweezers. Complete synthesis procedures and characterization can be found in the Supplementary Information. Solid-state NMR. Solid-state NMR experiments were conducted on a Bruker Avance DSX400 spectrometer operating at 13 C and 1H resonance frequencies of 100 and 400 MHz, respectively, using a Bruker double-resonance 4-mm magic-angle spinning (MAS) probehead. MMM samples were packed into the rotor as received, with a 3-mm thick glass spacer on the bottom of the rotor to keep all sample inside the radio-fre1 13 1 quency coil. H and C 90° pulse lengths were 4.2 μs, and H 26 TPPM decoupling was applied at |γB1|/2π = 60 kHz. Quan13 titative C NMR spectra were measured using multiCP at 14 kHz MAS,27 with a Hahn spin echo28 generated by a 180° pulse 29 1 H direct polarization with EXORCYCLE phase cycling. spectra were collected with a one-pulse probehead background suppression scheme30 at 14 kHz MAS. 13C-detected 1H T1r relaxation was measured with a |γB1|/2π = 40-kHz 1H spinlock ahead of 13C-1H Hartmann-Hahn cross polarization 31 (HHCP) at 7 kHz MAS and with total suppression of side32 1 13 bands (TOSS) before detection. H and C chemical shifts were referenced to hydroxyapatite at 0.18 ppm and to the carboxyl group of freshly-made crystalline glycine at 176.49 ppm, respectively. 1

2D HetCor NMR. H spin exchange between MOF and PEO can be observed with relatively good resolution in a two-di-

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mensional H- C heteronuclear correlation (HetCor) spec1 trum. Cross peaks link the H NMR frequency of the protons where the magnetization originated with the 13C frequency of 1 the carbon sites that received the magnetization after H spin 1 13 33 diffusion and H- C cross polarization. HetCor spectra were measured at 7.5 kHz MAS with frequency-switched Lee-Gold34 burg homonuclear decoupling, a mixing time tse for spin exchange or spin diffusion, 0.3 ms of cross polarization, and TOSS before detection. In the data analysis, the effective spin diffusion time during cross polarization was assumed to be 35 0.075±0.025 ms. Molecular Simulations. The [101] surface model of the dehydrated UiO-66 material was constructed using the BravaisFriedel-Donnay-Harker (BFDH)36-38 method applied to a preliminary DFT-optimized structure of the bulk MOF. The Lennard-Jones parameters, the Electrostatic Potential Fitting (ESP) partial charges as well as the description of the bonded contributions to the force field of the MOF model are detailed 25 elsewhere. Atomistic models for PVDF and PEO were constructed following a previously reported polymerization strategy.25 MOF and polymer were further combined through a series of force field MD cycles in the NVT and the NPnT ensemble, where Pn is the pressure component in the direction perpendicular to the slab, to generate the interface model and further analyze the penetration of the polymer into the MOF and the interactions in play. Full computational details are provided in the SI.

RESULTS AND DISCUSSION MMM Preparation and Model Development. MMMs were fabricated as previously reported,25 using PEO (Sigma Aldrich, 900,000 g/mol) and PVDF (Arkema, 750,000 g/mol) with various loadings of the Zr4+-based MOF UiO-66 from 30:70 (wt%) UiO-66/PEO to 80:20 UiO-66/PEO. A single MMM with 70:30 (wt%) UiO-66/PVDF was also prepared for study by NMR. The as-formed MMMs are uniform and sturdy (Figure S1), and SEM cryofracture cross-section images indicate uniformlydispersed MOF throughout the thickness of the membrane (Figures S2-S6). However, nitrogen sorption measurements show loss of UiO-66 microporosity at and below 70:30 UiO66/PEO loadings, while 80:20 UiO-66/PEO MMMs show half the expected surface area of the MOF component (Figure S7, Table S1). 70:30 UiO-66/PVDF MMMs show macroscale and SEM-scale uniformity (Figure S8) as well, but in nitrogen sorption measurements this MMM retains surface area proportional to that of the amount (wt%) of MOF present (Figure S9, Table S1). This difference in surface area retention between PEO and PVDF-based MMMs was noted in a previous publi33 cation and informally attributed to strong MOF–polymer interactions within the PEO MMMs that create a pore-blocking surface coating on the MOF particle surface. Here, we propose two possible models for MOF–polymer interactions that help us better understand these composite materials (Figure 1c, Figure S10): in the first, we obtain a uniform, limited infiltration layer on the MOF particles (surface-coating model), while in the second, significant infiltration of the PEO chains into and through the small, cage-like pores of UiO-66 is observed (homogeneous pore-infiltration model).

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Journal of the American Chemical Society also Figures S12 and S13). This line width increase is attributed 1 1 2to increased H- H dipolar couplings of the aromatic bdc protons from increased proton density within sub-nanometer distances, which again indicates significant PEO presence within the MOF pores. These data document more pervasive UiO66/PEO interactions than would be achieved in the surfacecoating model described in Figure 1c.

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b)

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c) Figure 1. a) Chemical structures of UiO-66 node and linker; b) schematic of MMM formation; c) two distinct models of 80:20 (wt%) UiO-66/PEO with particle size from SEM and realistic volume fractions. a) surface-coating model; b) homogeneous pore-infiltration model. NMR Evaluation of PEO MMMs. The clearest difference between our two proposed models is the large fraction (>50%) of MOF that is more than 15 nm from PEO in the surface-coating model with a 150-nm particle diameter (Figure 1c). Therefore, monitoring MOF signals for signs of PEO proximity is the most promising approach for determining the distribution of PEO within the MMMs among the two proposed models. Figure 2a and Figure S11 show 13C NMR spectra of the MOF 1-42benzene dicarboxylate (bdc ) linkers in a series of UiO266/PEO MMMs. Peak positions of bdc carbon atoms shift as the MOF component is decreased from 100 to 70 wt% UiO-66, then remain unchanged to 30 wt%. These chemical shift changes are analogous to solvent effects in solution NMR and indicate direct interactions between PEO segments and most, if not all, of the MOF linkers. The aromatic C-H groups from bdc2-, which protrude most prominently into the pore space, show the largest chemical-shift change due to PEO at ~130 ppm, further supporting the PEO infiltration model. A corresponding series of 1H NMR spectra in Figure 2b displays in2creasing line width of the aromatic protons of the bdc linkers in UiO-66 as MOF content decreases from 100 to 70 wt% (see

b) 13

Figure 2. a) C NMR peak positions of MOF linker moieties in UiO-66/PEO MMMs as a function of PEO content. The peak positions shift up to 30 wt% of PEO and then stabilize. The full spectra are shown in Figure S11. (b) Corresponding 1H


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NMR spectra of UiO-66/PEO MMMs. The linewidths of aromatic protons in MOF linker increase up to 30 wt% of PEO. The full spectra are shown in Figures S12 and S13. 13

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Corroborating the C and H spectral changes, Figure 3a de21 picts bdc signal intensity as a function of H spin-lock time, allowing determination of spin-lattice relaxation times in the rotating frame, 1H T1r, of both pristine MOF and MMMs. A longer relaxation time, such as that seen for pristine UiO-66 (15 ms), reflects limited large-amplitude segmental dynamics 1 with rates near 200,000/s. In all MMM systems, however, H T1r values of the linkers are drastically shortened compared to UiO-66 as the PEO content increases to 30 wt%. The proximity of PEO, which itself has an even shorter relaxation time of ~ 0.8 ms (Figure 3b) due its large-amplitude motions, appar2ently causes the faster relaxation of the bdc linkers through spin exchange from the fast-relaxing PEO protons to those of the linkers.

Figure 3. Effect of PEO on MOF, and of MOF on PEO, in 1H T1ρ NMR relaxation. a) A dramatic acceleration of 1H T1r relax13 1 13 ation of MOF linkers (detected via C after H- C cross polarization) due to the addition of PEO is observed. Squares: neat UiO-66; inverted triangles: 80:20 UiO-66/PEO; other symbols: ≤70:≥30 UiO-66/PEO. Once the pores are filled at ≥30 wt% PEO, the relaxation behavior remains unchanged. (b) A pronounced change of 1H T1r relaxation of PEO in UiO-66 (pentagons) is observed, relative to free amorphous PEO (open circles). Open pentagons: 80:20 UiO-66/PEO; filled pentagons: 70:30 UiO-66/PEO.

Figure 3a shows that the relaxation times for MMMs with UiO-66 loadings of ≤70 wt% are all essentially identical. This

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indicates, with high sensitivity, that the behavior and amount of PEO near the MOF linkers remains unchanged in materials with at least 30 wt% PEO present. Indeed, the MOF-linker NMR peak positions (Figure 2a), line shapes (Figure 2b), and relaxation times (Figure 3a) undergo pronounced changes up to 30 wt% PEO but remain unchanged as PEO content increases above 30 wt%. This indicates that 30 wt% PEO is absorbed in the MOF, which matches the pore-volume fraction of UiO-66 and correlates exactly with the observed loss of nitrogen-accessible surface area seen with ≥30 wt% PEO (Table S1 and Figure S7.) In addition, at ≥30 wt% PEO, we see evi1 dence of excess PEO outside of the MOF. At ≥30 wt% PEO, H NMR spectra exhibit the sharp signal of free amorphous PEO (see Fig. 2b), while at ≥50 wt% PEO, powder X-ray diffraction (PXRD) patterns show small peaks associated with PEO crystallinity (Figure S14) and DSC traces display a melting endotherm (Figure S15). 2D Heteronuclear Correlation (HetCor) Spectroscopy of PEO MMMs. The longest reach of the NMR methods employed in this study is achieved by 1H spin exchange or spin diffusion, which can be quantified in a 2D 1H-13C heteronuclear correlation (HetCor) experiment. HetCor allows differing spin exchange times (tse) to transfer magnetization between species which are not physically connected yet are close in space. Spatial proximity is seen in the appearance of characteristic crosspeaks after a specific tse. The appearance of cross peaks at very short spin-exchange times 90%) infiltration of PEO into the MOF in this cohesive MMM. The homogeneous distribution of PEO throughout UiO-66, given the great length of the polymer chains and the cohesive nature of the MMMs, is somewhat surprising. It is therefore worth considering how deeply the polymer must diffuse into the MOF particles to be compatible with the NMR data, to show PEO infiltration of at least 90% into every MOF particle. Analyzing a model with a MOF particle core free of polymer, as shown in Figure S20, demonstrates that a core of r = 35 nm in a 150-nm diameter particle makes up 10% of the particle volume. This means that the polymer must diffuse at least 40 nm deep into each UiO-66 particle. Our study shows quantitatively that the PEG-based pore-filling results of Uemura and others14,15 are extendable from small polymers (1000-20,000 g/mol) to high MW (900,000 g/mol), MMM-forming polymers, and from isolated MOF particles to cohesive MMM materials. HetCor of PVDF MMMs Compared to PEO MMMs. Extensive MOF–polymer interactions create an infiltrated MOF– polymer system in the case of UiO-66 and PEO. To compare with a different system, MMMs constructed of UiO-66 and PVDF were assessed. PVDF produces MMMs with UiO-66 that have good mechanical properties and, critically, retain the surface area of the MOF and MOF-based functionality such as postsynthetic modification (PSM) and dye filtration.23 Analysis of the UiO-66/PVDF interface by HetCor spectroscopy sheds light on the significant surface area differences seen in PEO and PVDF MMMs described above. The cross peaks in Figures 4a and 4c show that whereas high molecular weight PEO can penetrate many tens of nanometers deep into UiO-66, PVDF provides only a superficial interaction with 1 UiO-66 particles. Weak cross peaks between aromatic H of 21 the bdc linkers and PVDF methylene (-CH2-) groups in H13 C spectra of a 70:30 UiO-66/PVDF MMM contrast sharply with the strong, significant cross peaks observed in PEObased MMMs (Figure 4a). In the 70:30 UiO-66/PVDF MMM studied here, a slow increase in the cross-peak intensity was observed over time, see Figure 4c and Figure S21. This can be attributed to magnetization diffusing into a MOF particle from its PVDF-adhered surface. Accounting for the low proton density of the MOF, the thickness of the MOF surface layer able to be polarized by PVDF that is in reasonable contact with PVDF is roughly 3 nm (see SI), contrasting sharply with the >40 nm infiltration of PEO. Comparison of cross peak intensity in Figure 4b provides clear evidence for the difference in MOF–polymer interactions between PEO and PVDF. Molecular Simulations. Taken together, the PEO and PVDF MMM data demonstrate examples of both pore-infiltration and surface-coating models (Figure 1c) that match DSC, PXRD, and nitrogen sorption data of their respective MMMs.



MD simulations were conducted to further elucidate the nature of the MOF–polymer interface region and to provide a molecular explanation of the differences seen between PEO and PVDF interaction behaviors. To investigate the distribution of atoms of both polymer and MOF along the direction normal to the MOF surface (labeled as the z-coordinate, Figure 5), a model that incorporates both MOF and polymer and allows the interface to relax and intermix was developed. The black curves show the atomic distribution for UiO-66 located in the middle of the simulation box as depicted in the snapshot below the density plots of Figure 5. For UiO-66/PVDF simulations (Figure 5a), the red curve corresponding to PVDF covers the full box range, from z = 0 Å to z = 100 Å. It shows an irregular oscillation at low and high z values and drops to almost zero when entering the MOF surface region. This plot suggests an overlap between atoms of PVDF and UiO-66 over a length of about 20 Å ,which is much more pronounced than what was seen in previous models at room temperature (6±1 Å at 298 K),25 owing to the additional thermal energy (MD equilibrations performed at 1000 K) that allows the polymer to overcome the energy barrier for the penetration phenomenon to take place. By comparison, the density plots for the UiO-66/PEO system (Figure 5b) show an overlap between the two components over a much longer range, thus indicating a higher degree of penetration of PEO into the open pores of UiO-66 than that observed for PVDF for the same temperature (full z-length of the MOF of about 70 Å). This distinct simulated behavior suggests that the barrier for PEO penetration into the pores of UiO-66 is lower than for PVDF, consistent with the experimental findings. To further investigate the intermolecular interactions that favor the infiltration of the polymer inside the MOF pores, we computed radial distribution functions (RDFs) for several MOF/polymer atom pairs. RDFs reported in Figure S22 shows that the main interactions take place between the polymer F(PVDF) and O-(PEG) sites and the external part of the MOF surface, namely, the OH groups that terminate the Zr atoms. Moreover, RDFs presented in Figure S23 reveal that the most prominent interactions in the inner pores of the MOF surface take place between the polymer sites and the phenyl ring of the MOF. This latter result is fully consistent with the NMR findings which detected a perturbation of the linkers due to the presence of the polymer. Finally, the intensity of the interactions between PEO and UiO-66 is significantly higher than those between PVDF and UiO-66 for both the external and the internal part of the MOF surface (see the values in the y axis of the RDFs in Figures S22 and S23), which further illustrates the higher affinity between PEO and UiO-66 when compared to the UiO-66-PVDF case.

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pores of UiO-66 are fully (>90%) occupied by PEO. At 80 wt% UiO-66, we retain access to some MOF pores as well as favorable physical properties of a cohesive membrane. At PEO fractions ≥30 wt%, the excess polymer forms a semicrystalline matrix outside the MOF, which is clearly observed by NMR and DSC. Similar NMR studies on 70:30 UiO-66/PVDF MMMs show only limited PVDF–MOF contact in 2D HetCor NMR with long 1H spin diffusion; the limited polymer occupation of pores is confirmed by ready pore access deduced from nitrogen gas sorption. The differing ability of these two polymers to penetrate the pores of the MOF has been confirmed by molecular-dynamics simulations and is explained on the basis of the strength of site-to-site interactions. These studies establish solid-state NMR as a practical direct bulk measurement of MOF–polymer interactions in as-made, application-ready MMMs.

a)

CONCLUSIONS Overwhelming NMR evidence has been presented that in cohesive, freestanding flexible UiO-66/ PEO mixed-matrix membranes, essentially all linkers in UiO-66 are perturbed by high-molar-mass PEO: UiO-66 13C chemical shifts change, 1 UiO-66 H lines are broadened due to couplings to nearby protons of PEO, and UiO-66 1H T1r is dramatically shortened. Solid-state NMR, consistent with gas sorption experiments, shows that in 70:30 UiO-66/PEO MMMs, the small, cage-like

b) Figure 5. Atomic density profiles for UiO-66-PVDF (a) and UiO-66-PEO (b). Snapshots are shown for each interface. C, O, H, and F atoms are shown in grey, red, white, and green, respectively.

ASSOCIATED CONTENT


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Journal of the American Chemical Society Supporting Information. Computational details, NMR details, experimental details and additional experimental results including materials, synthetic procedures, and materials characterization.

AUTHOR INFORMATION Corresponding Authors [email protected]; [email protected]

[email protected];

guillaume.mau-

ACKNOWLEDGMENTS S.M.C. acknowledges generous financial support from the National Science Foundation, Division of Materials Research (DMR-1506059). J.C.M. was supported, in part, by the United States Department of Education GAANN Fellowship P200A150251 and the U.C. San Diego Frieda Daum Urey Fellowship. This work was performed in part at the San Diego Nanotechnology Infrastructure (SDNI) of U.C. San Diego, a member of the National Nanotechnology Coordinated Infrastructure, which is supported by the National Science Foundation (Grant ECCS-1542148).

REFERENCES (1) Furukawa, H.; Cordova, K. E.; O'Keeffe, M.; Yaghi, O. M. The chemistry and applications of metal-organic frameworks. Science 2013, 341, 1230444. (2) Kang, Z.; Fan, L.; Sun, D. Recent advances and challenges of metal-organic framework membranes for gas separation. J. Mater. Chem. A 2017, 5, 10073-10091. (3) Denny Jr, M. S.; Moreton, J. C.; Benz, L.; Cohen, S. M. Metal–organic frameworks for membrane-based separations. Nat. Rev. Mater. 2016, 1, 16078. (4) Huang, Y.-B.; Liang, J.; Wang, X.-S.; Cao, R. Multifunctional metal-organic framework catalysts: synergistic catalysis and tandem reactions. Chem. Soc. Rev. 2017, 46, 126-157. (5) Zornoza, B.; Tellez, C.; Coronas, J.; Gascon, J.; Kapteijn, F. Metal organic framework based mixed matrix membranes: An increasingly important field of research with a large application potential. Micropor. Mesopor. Mater. 2013, 166, 67-78. (6) Mahajan, R.; Koros, W. J. Factors controlling successful formation of mixed-matrix gas separation materials. Ind. Eng. Chem. Res. 2000, 39, 2692-2696. (7) Lin, R.; Villacorta Hernandez, B.; Ge, L.; Zhu, Z. Metal organic framework based mixed matrix membranes: an overview on filler/polymer interfaces. J. Mater. Chem. A 2018, 6, 293-312. (8) Ren, H.; Jin, J.; Hu, J.; Liu, H. Affinity between metal– organic frameworks and polyimides in asymmetric mixed matrix membranes for gas separations. Ind. Eng. Chem. Res. 2012, 51, 10156-10164. (9) Car, A.; Stropnik, C.; Peinemann, K.-V. Hybrid membrane materials with different metal–organic frameworks (MOFs) for gas separation. Desalination 2006, 200, 424-426.

(10) Venna, S. R.; Lartey, M.; Li, T.; Spore, A.; Kumar, S.; Nulwala, H. B.; Luebke, D. R.; Rosi, N. L.; Albenze, E. Fabrication of MMMs with improved gas separation properties using externally-functionalized MOF particles. J. Mater. Chem. A 2015, 3, 5014-5022. (11) Bae, T.-H.; Lee, J. S.; Qiu, W.; Koros, W. J.; Jones, C. W.; Nair, S. A high-performance gas-separation membrane containing submicrometer-sized metal–organic framework crystals. Angew. Chem. Int. Ed. 2010, 122, 10059-10062. (12) Rodenas, T.; van Dalen, M.; García-Pérez, E.; SerraCrespo, P.; Zornoza, B.; Kapteijn, F.; Gascon, J. Visualizing MOF mixed matrix membranes at the nanoscale: Towards structure-performance relationships in CO2/CH4 separation over NH2-MIL-53(Al)@PI. Adv. Funct. Mater. 2014, 24, 249-256. (13) Kitao, T.; Bracco, S.; Comotti, A.; Sozzani, P.; Naito, M.; Seki, S.; Uemura, T.; Kitagawa, S. Confinement of single polysilane chains in coordination nanospaces. J. Am. Chem. Soc. 2015, 137, 5231-5238. (14) Koh, K.; Wong-Foy, A. G.; Matzger, A. J. Coordination copolymerization mediated by Zn4O(CO2R)6 metal clusters: A balancing act between statistics and geometry. J. Am. Chem. Soc. 2010, 132, 15005-15010. (15) Uemura, T.; Yanai, N.; Watanabe, S.; Tanaka, H.; Numaguchi, R.; Miyahara, M. T.; Ohta, Y.; Nagaoka, M.; Kitagawa, S. Unveiling thermal transitions of polymers in subnanometre pores. Nat. Commun. 2010, 1, 83. (16) Yanai, N.; Uemura, T.; Kitagawa, S. Behavior of binary guests in a porous coordination polymer. Chem. Mater. 2012, 24, 4744-4749. (17) Yanai, N.; Uemura, T.; Kosaka, W.; Matsuda, R.; Kodani, T.; Koh, M.; Kanemura, T.; Kitagawa, S. Inclusion and dielectric properties of a vinylidene fluoride oligomer in coordination nanochannels. Dalton Trans. 2012, 41, 41954198. (18) Ding, N.; Li, H.; Feng, X.; Wang, Q.; Wang, S.; Ma, L.; Zhou, J.; Wang, B. Partitioning MOF-5 into confined and hydrophobic compartments for carbon capture under humid conditions. J. Am. Chem. Soc. 2016, 138, 10100-10103. (19) Distefano, G.; Suzuki, H.; Tsujimoto, M.; Isoda, S.; Bracco, S.; Comotti, A.; Sozzani, P.; Uemura, T.; Kitagawa, S. Highly ordered alignment of a vinyl polymer by host– guest cross-polymerization. Nat. Chem. 2013, 5, 335. (20) Uemura, T.; Horike, S.; Kitagawa, K.; Mizuno, M.; Endo, K.; Bracco, S.; Comotti, A.; Sozzani, P.; Nagaoka, M.; Kitagawa, S. Conformation and molecular dynamics of single polystyrene chain confined in coordination nanospace. J. Am. Chem. Soc. 2008, 130, 6781-6788. (21) Le Ouay, B.; Watanabe, C.; Mochizuki, S.; Takayanagi, M.; Nagaoka, M.; Kitao, T.; Uemura, T. Selective sorting of polymers with different terminal groups using metal-organic frameworks. Nat. Commun. 2018, 9, 3635. (22) Le Ouay, B.; Uemura, T. Polymer in MOF nanospace: from controlled chain assembly to new functional materials. Isr. J. Chem. 2018, 58, 995-1009.



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(23) Denny Jr., M. S.; Cohen, S. M. In situ modification of metal–organic frameworks in mixed-matrix membranes. Angew. Chem. Int. Ed. 2015, 54, 9029-9032. (24) Moreton, J. C.; Denny Jr., M. S.; Cohen, S. M. High MOF loading in mixed-matrix membranes utilizing styrene/butadiene copolymers. Chem. Commun. 2016, 52, 14376-14379. (25) Semino, R.; Moreton, J. C.; Ramsahye, N. A.; Cohen, S. M.; Maurin, G. Understanding the origins of metalorganic framework/polymer compatibility. Chem. Sci. 2018, 9, 315-324. (26) Bennett, A. E.; Rienstra, C. M.; Auger, M.; Lakshmi, K. V.; Griffin, R. G. Heteronuclear decoupling in rotating solids. J. Chem. Phys. 1995, 103, 6951-6958. (27) Duan, P.; Schmidt-Rohr, K. Composite-pulse and partially dipolar dephased multiCP for improved quantitative solid-state 13C NMR. J. Magn. Reson. 2017, 285, 68-78. (28) Hahn, E. L. Spin Echoes. Phys. Rev. 1950, 80, 580-594. (29) Bodenhausen, G.; Freeman, R.; Turner, D. L. Suppression of artifacts in two-dimensional J spectroscopy. J. Magn. Reson. 1977, 27, 511-514. (30) Chen, Q.; Hou, S. S.; Schmidt-Rohr, K. A simple scheme for probehead background suppression in one-pulse 1 H NMR. Solid State Nucl. Mag. 2004, 26, 11-15. (31) Hartmann, S. R.; Hahn, E. L. Nuclear double resonance in the rotating frame. Phys. Rev. 1962, 128, 2042-2053. (32) Dixon, W. T.; Schaefer, J.; Sefcik, M. D.; Stejskal, E. O.; McKay, R. A. Total suppression of sidebands in CPMAS C-13 NMR. J. Magn. Reson. 1982, 49, 341-345. (33) Caravatti, P.; Braunschweiler, L.; Ernst, R. R. Heteronuclear correlation spectroscopy in rotating solids. Chem. Phys. Lett. 1983, 100, 305-310. (34) Bielecki, A.; Kolbert, A. C.; De Groot, H. J. M.; Griffin, R. G.; Levitt, M. H. In Advances in Magnetic and Optical Resonance; Warren, W. S., Ed.; Academic Press: 1990; Vol. 14, p 111-124. (35) Chen, Q.; Schmidt-Rohr, K. Measurement of the local 1H spin-diffusion coefficient in polymers. Solid State Nucl. Mag. 2006, 29, 142-152. (36) Bravais, A. Etudes Cristallographiques; GauthierVillars: Paris, 1866. (37) Donnay, J. D. H.; Harker, D. A new law of crystal morphology extending the law of Bravais. Am. Mineral. 1937, 22. (38) Friedel, G. Etudes sur la loi de Bravais. Bull. Soc. Franc. Mineral 1907, 30, 326. (39) Clauss, J.; Schmidt-Rohr, K.; Spiess, H. W. Determination of domain sizes in heterogeneous polymers by solid-state NMR. Acta Polym. 1993, 44, 1-17.


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Polymer Infiltration into Metal-organic Frameworks in Mixed-Matrix

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