Research ArticleMATERIALS SCIENCE

A metal-organic framework with ultrahigh glass-forming ability

See allHide authors and affiliations

Science Advances  09 Mar 2018:
Vol. 4, no. 3, eaao6827
DOI: 10.1126/sciadv.aao6827
  • Fig. 1 Structural units and calorimetry of ZIF-62.

    (A) Similarity between tetrahedra in silicate glasses and ZIF-62 Im/bIm networks. (B) Cp and mass loss versus T, heated at 10 K min−1, following desolvation to eventual melting at Tm = 708 K. (C) Cp upscans of ZIF-62 glass quenched from above Tm showing a clear glass transition (Tg = 595 K), yielding Tg/Tm (0.84). Inset: Optical image of a transparent MQ glass.

  • Fig. 2 ZIF-62 ultrahigh GFA, high viscosity at Tm, and crystal-glass structural evolution.

    (A) XRD patterns of ZIF-62 glasses in argon at temperatures approaching Tm (0.88 < T/Tm < 0.92) for ta = 24 hours. AU, arbitrary units. (B) Crystalline and glass pair distribution functions D(r) with Im geometry identifying peaks 1 to 6, which are replotted from the study of Bennett et al. (17). (C) Raman spectra of crystal and glass. Insets: Changes in nodes (Zn-N) and linkers (C-N). (D) Temperature dependence of η for bIm/(Im + bIm) = 0.125 liquid with MYEGA (Mauro-Yue-Ellison-Gupta-Allan) fit (25). A two-parallel plate oscillation technique was used to avoid high-temperature oxidation, the first η measured for any MOF liquid.

  • Fig. 3 Effects of linker substitution on microstructure and thermodynamic characteristics.

    (A) bIm/(Im + bIm) ratios in both ZIF-62 crystal and glass from 1H liquid NMR (see the Supplementary Materials) versus synthesized values. The crystal structure was checked through XRD patterns (fig. S7). (B) 1H-13C CPMAS NMR spectra of crystalline samples of ZIF-62 with varying bIm/(Im + bIm) ratio highlighting bIm contributions [calculated shifts in black (see the Supplementary Materials)]. ppm, parts per million; expt., experiment; calc., calculation. (C) Increase in Tm and Tg with increasing bIm. Inset: Almost constant Tg/Tm for mixed linkers, compared to the 2/3 rule (57). (D) Increases in ΔHm and ΔSm on fusion with increasing bIm.

  • Fig. 4 The ultrahigh Tg/Tm ratio of ZIF-62.

    The comparison in Tg/Tm ratio between ZIF-62 and other types of glass-forming systems, including water (29, 30), oxide (33), metallic (34), and organic (35, 36)—good GFA typified by CPs, PMMA, B2O3, and SiO2 in contrast with the ultrahigh GFA of the ZIF-62.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/3/eaao6827/DC1

    Supplementary Methods

    fig. S1. Phase structure evolution with heating temperature.

    fig. S2. Comparison of valence states between crystal and glass.

    fig. S3. Porosity in MQ ZIF-62 glass.

    fig. S4. Porosity in MQ ZIF-62 glass.

    fig. S5. Determination of liquid fragility index (m).

    fig. S6. The appearance change of the MQ ZIF-62 glass with heating temperatures.

    fig. S7. XRD patterns of nonstoichiometric ZIF-62.

    fig. S8. Characterization of linker ratios.

    fig. S9. Influence of linker substitution on Tm and Tg.

    fig. S10. Characterization of linker distribution.

    fig. S11. Characterization of linker distribution.

    fig. S12. Characterization of linker distribution.

    fig. S13. Schematic representation of linker substitution.

    fig. S14. Poisson’s ratio of ZIF-62 crystal and glass.

    table S1. Synthesis parameters for ZIF-62.

    table S2. PALS data for ZIF-4 glass and ZIF-62 glass.

    table S3. Evolution of the thermodynamic parameters and Tg with increasing bIm.

    table S4. Tg/Tm, Tm, and glass-crystal density deficit Δρ/ρg for the materials highlighted in Fig. 4.

    References (3742)

  • Supplementary Materials

    This PDF file includes:

    • Supplementary Methods
    • fig. S1. Phase structure evolution with heating temperature.
    • fig. S2. Comparison of valence states between crystal and glass.
    • fig. S3. Porosity in MQ ZIF-62 glass.
    • fig. S4. Porosity in MQ ZIF-62 glass.
    • fig. S5. Determination of liquid fragility index (m).
    • fig. S6. The appearance change of the MQ ZIF-62 glass with heating temperatures.
    • fig. S7. XRD patterns of nonstoichiometric ZIF-62.
    • fig. S8. Characterization of linker ratios.
    • fig. S9. Influence of linker substitution on Tm and Tg.
    • fig. S10. Characterization of linker distribution.
    • fig. S11. Characterization of linker distribution.
    • fig. S12. Characterization of linker distribution.
    • fig. S13. Schematic representation of linker substitution.
    • fig. S14. Poisson’s ratio of ZIF-62 crystal and glass.
    • table S1. Synthesis parameters for ZIF-62.
    • table S2. PALS data for ZIF-4 glass and ZIF-62 glass.
    • table S3. Evolution of the thermodynamic parameters and Tg with increasing bIm.
    • table S4. Tg/Tm, Tm, and glass-crystal density deficit Δρ/ρg for the materials highlighted in Fig. 4.
    • References (37–42)

    Download PDF

    Files in this Data Supplement:

Navigate This Article