UC San Diego

Metal-organic frameworks (MOFs) are a diverse class of porous materials that hold great promise for providing low-cost solutions in a wide range of applications. Their native, powdered form, however limits their inherent utility. Through fabrication of polymer composites, these materials can be prepared in engineered forms that exploit the useful attributes of MOFs in application-ready forms.

MOFs that are fabricated into membranes are an especially useful form factor for these engineered materials. Chapter 2 describes the development of mixed matrix membranes (MMMs) with a variety of MOF species. The work shows that the inherent porosity and chemical tunability of the MOFs is retained when prepared in the composite MMM, providing a material that effectively exploits the MOF properties while enhancing the ease of handling and implementation of the MOF material.

Chapter 3 shows that not only are the MOF properties retained in the MMM, but that fabrication of the composite material can actually enhance the stability of the MOF in the MMM. A copper-based MOF (HKUST-1) is explored for personal protection against toxic industrial chemicals due to its strong ammonia adsorption behavior. While the native MOF displays high uptake initially, it is unstable and degrades rapidly even in ambient moisture. The MOF in the MMM, however, remains highly active even after aging under harsh conditions for a month.

Chapter 4 details various methods for incorporating multiple MOF species into a single MMM for multifunctional materials. Methodologies for fabricating spatially segregated MOF species, fully mixed MOF species, and layered MOF species are described, as well as incorporation ad activation of a cross-linking agent in the MMM formulation to improve the range of solvent tolerance.

In Chapter 5, a method for producing melt-processable, covalently integrated MOF-polymer composites is described. Using a postsynthetic polymerization strategy, MOF particles are incorporated into polyamide chains to generate a next generation MOF-polymer composite material. Multiple polymer syntheses are investigated and the materials are shown to retain the MOF crystallinity and polymer melt characteristics in the composite materials.