Herein we report a new microwave-assisted synthetic strategy to rapidly prepare hybrid zeolitic–imidazolate frameworks (ZIFs): ZIFs with mixed metal centers and/or mixed linkers.

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Despite the potential of C 3 H 6 /C 3 H 8 separation, there have been no industrial applications of zeolitic-imidazole framework-8 (ZIF-8) mixed-matrix membranes (MMMs) because of the moderate separation performances and several challenging processing issues. Herein, we present a new paradigm of MMM fabrication, named polymer-modification-enabled in situ metal−organic framework formation (PMMOF), enabling in situ formation of ZIF-8 fillers inside the 4,4-(hexafluoroisopropylidene)diphthalic anhydride 2,4,6-trimethyl-1,3phenylenediamine polymer. PMMOF consists of four steps including hydrolysis of a polymer, ion-exchange, ligand treatment, and imidization. Each step was thoroughly analyzed and important processing parameters were identified, enabling the structural control of MMMs by PMMOF. The binary C 3 H 6 /C 3 H 8 separation performance of the MMMs showed much higher separation factors than conventionally prepared MMMs at similar filler loadings, satisfying the commercial C 3 H 6 /C 3 H 8 separation performance criteria. PMMOF was successfully applied for other MOFs, demonstrating that the process could be general. Finally, as a proof of concept, asymmetric mixed-matrix hollow fiber membranes (i.d. of 0.45 mm and o.d. of 0.63 mm) with ultrathin selective skin layers were prepared by PMMOF, showing C 3 H 6 permeance of 2.17 GPU and C 3 H 6 /C 3 H 8 separation factor of ∼20.

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We present anovel synthesis strategy termed delayed linker addition (DLA) to synthesize hybrid zeolitic-imidazolate frameworks containing unsubstituted imidazolate linkers (Im) with SOD topology (hereafter termed Im/ZIF-8). Im linker incorporation can create larger voids and apertures, which are important properties for gas storage and separation. To date,there have been only ahandful of reports of Im linkers incorporated into ZIF-8 frameworks,t ypically requiring arduous and complicated post synthesis approaches.D LA, as reported here,i sasimple one-step synthesis strategy allowing high incorporation of Im linker into the ZIF-8 framework while still retaining its SOD topology.W ef abricated mixedmatrix membranes (MMMs) with 6FDA-DAM polymer and Im/ZIF-8 obtained via DLA as af iller.T he Im/ZIF-8containing MMMs showed excellent performance for both propylene/propane and n-butane/i-butane separation, displaying permeability and ideal selectivity well abovet he polymer upper bound. Moreover,highly detailed molecular simulations shed light to the aperture sizea nd flexibility response of Im/ ZIF-8 and its improved diffusivity as compared to ZIF-8.

In situ formation of multifunctional MOF thin films and composites using the PMMOF process.

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