Synthetic Control over MOF Particle Growth and Surface Chemistry

基于金属-有机框架（mof）的膜是一种三维（3-D）有机/无机化合物，由于其优异的可调性和合成多样性，在工业石油炼制和气体分离领域引起了人们的强烈兴趣。然而，为了使MOF在工业领域获得广泛的吸引力和应用，研究人员将需要超越3-D MOF，开发新型的MOF纳米颗粒，因为它们具有优异的分离性能，并产生具有优异稳定性的膜。在过去的二十年里，MOF的散装粉末一直是MOF学术研究的焦点，但最近的注意力转向了制备纳米MOF和精确控制粒径的聚合物复合材料。尽管初步证明了MOF纳米颗粒的巨大潜力，但关键的基本问题仍然是实现对MOF颗粒组成的可重复性控制，以及了解颗粒大小和组成如何影响膜的性能。该项目由美国国家科学基金会材料研究部固态与材料化学项目支持，俄勒冈大学的Carl Brozek教授和他的研究小组将研究控制MOF纳米晶体精确尺寸和组成的化学原理。机械生长模型将在为其他类别的材料建立的生长模型的背景下发展，以便这些结果为材料化学的广泛领域提供信息。同样，本提案中所追求的合成技术将通过概述跨多种尺寸体系的材料分子控制的基本工具，影响MOF颗粒以外的材料设计。所提出的研究与社会实际相关，因为对MOF纳米晶体尺寸的精确控制将为工业改进气体分离膜开辟新的领域，并为提高MOF的应用性能提供机会。该项目由美国国家科学基金会材料研究部固态和材料化学项目支持，将研究金属有机框架（MOF）颗粒的基本生长机制，开发控制颗粒表面化学的方法，以提高其胶体稳定性和与聚合物复合材料的界面，并了解尺寸和表面组成对分子和电荷传输性质的影响。要实现这一目标，需要对决定颗粒大小、缺陷合并和表面功能化的参数进行基本调查。本研究将有助于研究如何控制材料的预成核晶体生长、可重复合成MOF基异质结构复合材料以及提高MOF材料的实际应用价值。该提案的更广泛影响包括：1)将这些研究目标整合到教育推广计划中，向缺乏服务的学生传播碳捕获技术的科学；2)促进跨学科培训计划，将化学与建筑专业的学生结合起来设计空气净化模块；3)赞助基于mof的碳捕获的工业-学术界系列研讨会；4)实施一门面向俄勒冈大学（University of Oregon）化学博士生全年开放的设计拓展计划教学课程。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical SummaryMembranes based on metal-organic frameworks (MOFs), which are three-dimensional (3-D) organic/inorganic compounds, attract intense interest for industrial petroleum refining and gas separations due to their exceptional tunability and synthetic diversity. For MOFs to reach widespread attraction and implementation in the industrial sector, however, researchers will be required to go beyond 3-D MOFs and develop new types of MOF nanoparticles, as they exhibit superior separation performance and generate membranes with superior stability. For the past two decades, bulk powders of MOFs occupied the focus of academic MOF research, but very recent attention has turned to preparing MOF nanoparticles and polymer composites with precise control of particle sizes. Despite preliminary demonstrations of the great potential of MOF nanoparticles, key fundamental questions remain for achieving reproducible control over MOF particle composition and for understanding how particle size and composition impact membrane performance. With this project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, Prof. Carl Brozek at the University of Oregon and his research group will investigate the chemical principles that control the precise sizes and compositions of MOF nanocrystals. Mechanistic growth models will be developed in the context of growth models established for other classes of materials so that these results inform the broad field of materials chemistry. Similarly, the synthetic techniques pursued in this proposal will influence materials design beyond MOF particles, by outlining fundamental tools for molecular control over materials across multiple size regimes. The proposed research is practically relevant to society because precise control over MOF nanocrystal sizes will open new frontiers in improved gas separation membranes for industry and the opportunity for elevating MOF application performance to becoming practically relevant. Technical Summary This project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, will investigate the fundamental growth mechanisms of metal-organic framework (MOF) particles, develop methods to control particle surface chemistry for enhancing their colloidal stability and interfacing with polymer composites, and understand the impact of size and surface composition on molecular- and charge-transport properties. Tackling this goal will require basic investigation into the parameters that dictate particle sizes, defect incorporation, and surface functionalization. Insight into controlling prenucleation crystal growth of materials in general, reproducible synthesis of MOF-based heterostructure composites, and improving the practical relevance of MOF materials will result from this research. Broader impacts of this proposal include 1) integrating these research aims into educational outreach initiatives that communicate the science of carbon capture technology to underserved students, 2) fostering interdisciplinary training programs that pairs chemistry with architecture students to design air-purification modules, 3) sponsoring industry-academia seminar series on MOF-based carbon-capture, and 4) implementing a teaching course on designing outreach initiative offered year-round to University of Oregon (UO) chemistry PhD students.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.