CAREER: Molecular Layer Deposition of Porous Organic Frameworks

控制材料合成和生长的技术进步一直是许多科学发现的基石。为此，该项目的目标是实现一种新的绿色路径，使超薄纳米多孔薄膜能够高精度沉积。提出了一种分子层沉积(MLD)方法，用于在单步无溶剂涂层过程中构建具有广泛可调孔隙率范围的薄膜。该项目代表着实现气相合成多孔有机骨架(POF)的重要一步，并将为将这些薄膜集成到用于水净化、气体和液体分离系统以及植入性生物人造器官和药物输送系统的高效和高选择性过滤器铺平道路。这项拟议的工作将创造一种新的制造工艺，因为它能够合成尚未加工成薄膜的POF。此外，建议的研究路径允许研究这些骨架的物理和化学性质，这对于开发低环境影响和能源足迹的制造工艺至关重要。这项研究的首席研究员(PI)将利用他们独特的材料处理平台和分离科学专业知识，将有机骨架作为活动层集成到高效分子分离技术中。该项目的一个优先事项是将研究成果转化为教育和推广活动，通过探索分子工程的先进概念，吸引代表不足的K到研究生水平的学生参加STEM。面向本科生和高中生的暑期项目将让学生接触反应工程的基础知识，激励他们追求以研究为导向的职业生涯，成为终身学习者--这是国家科学基金会的十大想法中强调的关键需求。在这个项目中开发的所有教育组成部分将在一个在线门户网站上维护，以帮助提高与分子和高分子工程有关的公众素养。该项目的目标是解决与自下而上合成多孔有机骨架(POF)相关的挑战，方法是对溶解度有限的多官能团单体进行干法聚合，或者在其聚合物难以溶于溶剂的情况下进行聚合。通过研究无溶剂聚合的气相工艺参数，将为原位合成共价多孔骨架提供一个新的平台。为了实现有机骨架的干法聚合，将在分子层沉积(MLD)过程中研究两种不同的缩聚方案(氧化缩聚和亚胺缩聚)。由于目前还没有已知的干法沉积薄膜POF的报道，目前的项目将创造与以分子精度处理这些材料有关的新知识。通过在控制聚合反应网络速率的参数空间中导航，可以控制生长薄膜的化学成分和孔隙率，以基于目标分离应用来调节薄膜的渗透性和选择性。为了实现这一目标，我们将利用肖尔的方案确定控制氧化缩聚反应的参数，然后评估单体化学在MLD加工中所起的作用，最后将进行用于纳滤应用的这些多孔骨架的原位合成和集成。对于第二组亚胺缩聚反应将采取类似的方法。与拟议的研究计划相一致，将大力整合研究和教学活动，以促进两者之间的互惠关系。宣传和教育活动将努力加强少数群体和代表不足群体的学生对与材料加工、表面科学和分子工程有关的研究课题的参与。通过研究，将制定一个暑期计划，以提高公众的科学素养，并吸引学生从事分子工程的研究。计划开设一门新的跨学科课程，以半导体制造中的薄膜加工为中心。由此产生的本课程的教育内容、外展活动和暑期计划将通过内布拉斯加州大学林肯公共数字图书馆数字社区向公众开放。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。

The technological advances made to control the synthesis and growth of materials have been the cornerstone of many scientific discoveries. To that end, the goal of this project is to realize a new green pathway enabling the high-precision deposition of ultra-thin nanoporous films. A molecular layer deposition (MLD) approach is proposed to construct films that feature a wide and tunable range of porosity in a single-step solvent-free coating process. This project represents a major step towards realizing the vapor-phase synthesis of porous organic frameworks (POFs) and will pave the way to integrating these films into energy efficient and highly selective filters for water purification, gas and liquid separation systems, and implantable bioartificial organs and drug delivery systems. The proposed work will create a novel manufacturing process, as it enables the synthesis of POFs that have not yet been processed as thin films. Additionally, the proposed research pathway allows for studying the physical and chemical properties of these frameworks, essential for developing fabrication processes with low environmental impact and energy footprint. The principal investigator (PI) of this study will leverage their unique materials processing platform and separation science expertise to integrate organic frameworks as active layers in high-efficiency molecular separation technologies. A priority of this project is to translate research findings into educational and outreach activities, engaging underrepresented K-to-graduate level students in STEM by exploring advanced concepts in molecular engineering. Summer programs for undergraduate and high school students will expose students to the fundamentals of reaction engineering, inspiring them to pursue research-oriented careers and become lifelong learners - a critical need highlighted in the National Science Foundation's 10 Big Ideas. All the educational components developed in this project will be maintained on an online portal to help increase public literacy pertaining to molecular and macromolecular engineering. The goal of this project is to tackle the challenges associated with the bottom-up synthesis of porous organic frameworks (POFs) by dry polymerization of polyfunctional monomers that have limited solubilities or in cases where their polymers are solvent intractable. By investigating the vapor phase processing parameters for a solvent-free polymerization pathway, a new platform for the in-situ synthesis of covalent porous frameworks will be developed. To realize dry polymerization of organic frameworks, two different polycondensation schemes (oxidative and imine-based) will be studied within a molecular layer deposition (MLD) process. Because no known dry routes to deposition of thin-film POFs have been reported, the current project will create new knowledge pertaining to processing these materials with molecular precision. By navigating the space of parameters governing polymerization reaction network rates, chemical composition and porosity of the growing films can be controlled to tune film permeability and selectivity based on the target separation application. To achieve this objective, the parameters that control the oxidative polycondensation reactions will be identified using Scholl's scheme, then the role monomer chemistries play in MLD processing will be evaluated, and lastly the in-situ synthesis and integration of these porous frameworks for nanofiltration applications will take place. A similar approach will be taken for second set of imine polycondensation reactions. Congruent with the proposed research plan, significant effort will be placed on integrating research and teaching activities to foster a reciprocal relationship between the two. Outreach and educational activities will strive to enhance the participation of students from minority and underrepresented groups in academia in research topics relevant to materials processing, surface science, and molecular engineering. A summer program, informed by research, will be developed to improve public science literacy and to attract students to research in molecular engineering. A new interdisciplinary course centered on thin-film processing for semiconductor manufacturing is planned. The resulting educational content of this course, the outreach activities, and summer programs will be available to the public via the University of Nebraska-Lincoln public digital library, Digital Commons.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.