Research Overview

Metal-organic frameworks (MOFs) and their sub-class zeolitic-imidazole frameworks (ZIFs) are the major porous materials for our research. They can be utilized for diverse separation applications due to their tunable structural and chemical properties, and wide ranges of pore sizes with various crystal structures. In addition, our research is extending to the immerging organic-based porous materials including covalent-organic frameworks (COFs), porous-organic cages (POCs), etc. having a great potential to enable high-performance separations. The pore size of those materials can be controlled by narrowing/widening pore sizes and changing flexibilities by the means of chemical and physical modifications such as introducing functional groups, developing multi-component systems, varying crystallinity, impregnating substances, and irradiating a high-energy source. Such methods also allow for the improvement of material stabilities and hydrophilicity/hydrophobicity.

For energy-efficient separations, the developments of diverse membranes and membrane fabrication methodologies are being conducted in our lab. Economical and facilely scalable polymer membranes, high-performance polycrystalline membranes, polymer/sieve hybrid mixed-matrix membranes (MMMs), and others (i.e., ionic liquid and carbon molecular sieve membranes) are studied to meet different separation requirements. In particular, improving the scalability and separation performances of polycrystalline membranes and MMMs are our primary concerns in investigating membranes. With respect to these, we introduce unconventional polymer formation processes and novel synthesis strategies of molecular sieves for instance the in-situ nucleation and growth of crystals in polymer matrices for MMM fabrications and the in-situ surface polymerization to seal microstructural defects of a polycrystalline membrane.

We are interested in diverse separation applications: light gas separations, including direct air capture (DAC), special gas separations, and water vapor separation. In an effort to save energy and cost required for those separations, membrane and adsorption-based separation techniques have been actively studied as promising alternatives to energy-intensive thermally-driven processes. Differences in physical (size and shape) and chemical (polarity and interaction) properties of two or more gas species enable selectively separate targeted gas molecules from a mixture using membranes and sorbents. Since the separation efficiency of membranes and sorbents highly relies on the performance of separation materials, it is of critical importance to develop high-performance, stable, and processible separation materials for specific separations.