Collaborative Research: Scalable Manufacturing of Large-Area Thin Films of Metal-Organic Frameworks for Separations Applications

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This grant supports research that contributes knowledge to the formation of metal-organic framework (MOF) thin films, a class of porous materials that has the power to transform separations science and its applications. MOFs are useful for a wide range of applications, from charge and ion transport, separations, gas- and solution-based sensing, catalysis, environmental remediation, and more. The formation of large-area separation membranes is especially significant for a range of gas separations, such as for CO2 removal from air or flue gas. Small-scale (1 cm2) MOF-based membranes have shown utility for a range of high-value separation applications. However, a lack of fundamental knowledge exists to create easily scalable, advanced manufacturing of large areas of MOF membranes that still preserve the lab-scale performance. This award supports a combination of x-ray probes, modeling, and experimental techniques to fully understand how MOF thin films form. This fundamental knowledge is used to develop a continuous, roll-to-roll coating technique that can create large-area MOF thin films with outstanding separation performance. Students are engaged to contribute to the development of new MOF crystallization theories and modeling tools that can be used in research as well as industrial environments. The project endeavors to train students, particularly from underrepresented minority backgrounds, to become successful chemical engineers and material scientists. Large area, scalable thin-film MOF formation required for low-resistance, low-cost separations is difficult to achieve due to limited know-how on controlling solution chemistry for precision synthesis of MOF thin films using a scalable solution coating process. This project uses an integrated approach involving in-situ experimentation, modeling, and separation measurements to obtain fundamental manufacturing research on MOF thin film formation using scalable coating techniques, such as flow coating, or the recently developed percolation-assisted coating (PAC) method. Rapid timescale, in-situ x-ray scattering measurements coupled with microkinetic modeling are used to understand thin film MOF nucleation and growth mechanisms under evaporative/pervaporation conditions. The microkinetic model simulates billions of oligomerization reactions to predict nucleation rate, growth rate, and size distribution. The microkinetic model helps in selecting a range of operating conditions for high throughput (HT) PAC experiments for the optimization of MOF thin film structure and maximizing performance. By connecting it to a gas chromatograph, the HT setup is also used to obtain gas separation factors for CO2/N2 and CO2/CH4 mixtures. The ensuing process-structure-property relationships guide the scaling of the PAC method to grow 50 cm2 MOF films, followed by a model-based design of a roll-to-roll coating system for large-scale manufacturing of MOF films.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.