Tailoring metal-organic framework glasses with higher fracture toughness
Metal-organic frameworks (MOFs) are a class of organic-inorganic hybrid materials with high porosity. Recently, it has been discovered that a subset of MOFs, namely zeolitic imidazolate frameworks (ZIFs), can be melted and quenched into glasses. This makes it possible to prepare bulk, transparent ZIF glasses with modifiable organic and inorganic building units. However, preliminary results have shown that one of the representative ZIF glasses, ZIF-62, exhibits lower fracture toughness than most traditional oxide glasses. This seriously limits the scope of possible ZIF glass applications within, e.g., gas separation and storage.

In the proposed project, we will explore the composition-structure-mechanical property relationship of ZIF glasses. The aim is to optimize the glass composition and structure to achieve improved fracture toughness, while not significantly lowering the strength and stiffness. To this end, we will first systematically vary the ZIF glass structure by tuning the composition, thermal history, and pressure history, in addition to subjecting the glasses to irradiation by heavy ions. Then the mechanical properties of the different glasses will be measured. Finally, these experiments will be complemented by atomistic simulations and machine learning predictions to identify optimized glass structures with improved mechanical performance.

The project builds on complementary expertise of the fellow applicant (atomistic simulations, machine learning) and supervisor (mechanics, MOF glasses). Together with the research and training environment provided by the host organization (Aalborg University, Denmark), this will ensure the achievement of this timely and innovative project as well as the dissemination and exploitation of the expected results. The research outputs will lead to new understanding of fracture behavior of MOF materials. The fellow applicant will emerge from the project with new skills, and the capability to launch his own research group.