Annealing (glass)

Metal

Amorphous solid

Adsorption

Metallurgy

Materials science

Indentation

Nanoindentation

Creep

Physical chemistry

Polymer

Amorphous metal

Nanotechnology

Organic chemistry

Glass transition

Metal-organic framework

Scratch

Chalcogenide glass

Composite material

Chalcogenide

Crystallography

Chemistry

Hot pressing

Journal of the American Chemical Society

Melt quenched metal–organic framework (MOF) glasses define a new category of glass, distinct from metallic, organic, and inorganic glasses, owing to the dominant role of metal–ligand coordination bonding. The mechanical properties of glasses in general are important given their application in protective coatings and display technologies, though little is known about MOF glasses in this respect. The experimental elucidation of key properties such as their scratch resistance has been limited by the lack of processing methodologies capable of producing bulk glass samples. Here, nanoindentation was used to investigate the Young's modulus and hardness of four melt-quenched glasses formed from zeolitic imidazolate frameworks (ZIF): agZIF-4, agZIF-62, agZIF-76, and agZIF-76-mbIm. The creep resistance of the melt-quenched glasses was studied via strain-rate jump (SRJ) tests and through constant load and hold (CLH) indentation creep experiments. Values for the strain-rate sensitivity were found to be close to those for other glassy polymers and Se-rich GeSe chalcogenide glasses. Vacuum hot-pressing of agZIF-62 resulted in an inhomogeneous bulk sample containing the glass and amorphous non-melt-quenched aZIF-62. Remelting and annealing, however, resulted in the fabrication of a transparent, bubble-free bulk specimen, which allowed the first scratch testing experiments to be performed on an MOF glass.

Mechanical Properties and Processing Techniques of Bulk Metal–Organic Framework Glasses