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

这笔赠款支持为金属-有机骨架(MOF)薄膜的形成贡献知识的研究，MOF薄膜是一类具有改变分离科学及其应用的能力的多孔材料。MOF具有广泛的用途，从电荷和离子传输、分离、基于气体和溶液的传感、催化、环境修复等等。大面积分离膜的形成对于一系列气体分离特别重要，例如用于从空气或烟道气中去除二氧化碳。基于MOF的小规模(1cm2)膜已显示出在一系列高价值分离应用中的实用价值。然而，在为大面积MOF膜开发易于扩展的先进制造工艺方面，仍然缺乏基础知识，这些工艺仍然保持实验室规模的性能。该奖项支持使用X射线探头、建模和实验技术相结合的研究，以充分了解MOF薄膜是如何形成的。这一基本知识被用来开发一种连续的、卷到卷的涂覆技术，该技术可以创建具有出色分离性能的大面积MOF薄膜。学生致力于开发新的MOF结晶理论和建模工具，这些理论和建模工具可用于研究和工业环境。该项目致力于培养学生，特别是来自少数族裔背景的学生，成为成功的化学工程师和材料科学家。低电阻、低成本分离所需的大面积、可伸缩薄膜MOF的形成很难实现，因为使用可伸缩溶液涂层工艺精确合成MOF薄膜的溶液化学控制技术有限。该项目使用包括现场实验、建模和分离测量的综合方法，使用可伸缩涂层技术(如流动涂层或最近开发的渗流辅助涂层(PAC)方法)对MOF薄膜的形成进行基础制造研究。采用快速时间刻度、原位X射线散射测量和微观动力学模拟相结合的方法，对蒸发/渗透蒸发条件下薄膜MOF的成核和生长机制进行了研究。微观动力学模型模拟了数十亿次齐聚反应，以预测成核速率、生长速率和尺寸分布。微观动力学模型有助于为高通量(HT)PAC实验选择一系列操作条件，以优化MOF薄膜结构和最大化性能。通过将其连接到气相色谱仪，HT装置还可用于获得二氧化碳/氮气和二氧化碳/甲烷混合物的气体分离系数。随后的工艺-结构-性能关系指导了PAC方法的扩展，以生长50 cm2 MOF薄膜，随后基于模型设计了用于大规模制造MOF薄膜的卷到卷涂层系统。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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 develop easily scalable, advanced manufacturing process for large areas of MOF membranes that still preserve lab-scale performance. This award supports research using 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 perform 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.