Effects of Isothermal Treatment on A_gZIF-62: Implications on Porosity, Separations, and Grain Boundary Defect Removal

Glasses derived from metal-organic frameworks (MOFs) combine the processing benefits of glassy materials with the accessible and selective porosity of MOFs, with potential applications in gas separation and electronics. Establishing control over MOF glasses requires an accurate understanding of how processing parameters will affect the resulting glass properties. To advance this understanding, the effect of isothermal melt treatment conditions on the porosity and morphology of ZIF-62 is investigated. It is demonstrated that the transition from crystal to glass increased in fractional free volume (3.78 ± 0.07% to 5.50 ± 0.03%, respectively) while impeding the accessibility of CO₂, N₂, and propene by 59-79%. It is demonstrated that the change in pore volume is independent of isothermal hold times. In contrast, isothermal hold time allows control over glass morphology, where short treatments retained more original morphological characteristics, while longer treatments improved grain coalescence.