Precise control over gas-transporting channels in zeolitic imidazolate framework glasses.

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Porous metal-organic frameworks (MOFs) offer solutions for societal challenges like CO2 sequestration.
• Zeolitic imidazolate frameworks (ZIFs) can transition into a glass state, combining glass properties with MOF potential.
• ZIF glasses offer enhanced processability for gas separation applications.

Purpose of the Study:

• To demonstrate the scalability and processability of ZIF-62 crystals and glasses.
• To investigate the gas penetration dynamics and pore architecture evolution in ZIF crystals and glasses.
• To analyze the crystal-to-glass transition and thermal processing capabilities of ZIF materials.

Main Methods:

• Infrared microimaging to track gas penetration and pore evolution.
• Microscope-coupled heating stage for in situ observation of melting and processing.
• Transmission electron microscopy for microstructural analysis.
• Mass spectrometry to study the crystal-to-glass transition.
• Density and volume measurements to track pore collapse.

Main Results:

• Demonstrated scalability of millimetre-sized ZIF-62 crystals and centimetre-sized ZIF-62 glass.
• Quantified diffusion coefficients and characterized ångström-scale pore architecture changes.
• Observed in situ material evolution during melting and processing across multiple length scales.
• Tracked pore collapse during glass processing via volume and density changes.
• Investigated thermal processing ability and crystal-to-glass transition.

Conclusions:

• ZIF glasses are scalable and processable materials with potential for gas separations.
• Understanding pore evolution during processing is crucial for optimizing ZIF glass membranes.
• Controllable tuning of pore diameter in ZIF glass could lead to advanced liquid-processable membranes for challenging gas separations.