Metal-Organic Framework Monoliths Derived from Emulsion-Templated Foams for Reactive Filtration

Metal-organic frameworks (MOFs) are a promising class of materials for the sorption and reactive elimination of toxic chemicals; however, the limited processability of MOF powders hinders their broader application in this field. High internal phase emulsion-derived polymer foams (polyHIPEs) offer a promising avenue for generating interconnected macroporous structures with highly tunable physical and chemical properties. Combining polyHIPEs with reactive MOFs offers a versatile platform for removing toxic chemical vapors and gases, but studies that investigate the effects of MOF loading on a polyHIPE and how the composite matrix influences MOF reactivity are limited. In this work, the MOF UiO-66-NH₂ is used as a filler in the one-pot synthesis of polyHIPE composites. The MOF is shown to play a key role in the stabilization of the emulsion during polymerization at elevated temperatures, preventing droplet coalescence and pore collapse. The MOF filler is also shown to maintain its adsorption activity, although the overall performance of the composite is strongly influenced by temperature due to limited diffusion through the polymer matrix at reduced temperatures. Finally, cyclic compression tests indicate that increased MOF loadings cause a reduction in recoverable deformation, as indicated by a drop in the hysteresis toughness between the first and second compression cycles driven by microcrack formation and debonding at the matrix-filler interface. These experiments highlight that understanding the interactions between MOF fillers and the polymer matrix is the key to balancing the reactivity and mechanical stability of these composite systems.