EAGER: High-Gradient-Strength NMR Accessories for Transport Measurements in Advanced Nanomaterials and Microstructures

[142111] leisene这个探索性研究（EAGER）项目的早期概念资助的目标是研究(i)产生功能化纳米管的汤中的反应物，（ii）设计纳米管中的探针分子，（iii）工程微接触器中的流体，（iv）具有多环拓扑结构的大分子，以及(v)阴离子交换燃料电池中的阴离子的分子水平运输。这些研究将通过扩散核磁共振（NMR）进行，使用在现有核磁共振光谱仪上获得的专用设备（高梯度强度扩散探针和梯度放大器）。由此产生的新的实验能力迫切需要在流体动力学、分离、纳米和微流体、纳米工程、能量转换和燃料电池开发方面进行探索性研究。所提议的活动的智力价值体现在需要强梯度核磁共振扩散测量的研究推进中：(i)纳米管生长和工程的机制研究——所要求的核磁共振附件将能够测量纳米颗粒的大小和结构，从而对水溶液中制备的单壁无机纳米管的生长机制产生重要的见解。这些知识对于纳米管的发展至关重要，纳米管在电子、分离和能源存储/发电/管理等各种转型技术中都有应用。（二）纳米管中的传输-管状材料中的纳米流体传输尽管具有科学和技术相关性，但人们对其了解甚少。无机纳米管（基于金属氧化物）和有机纳米管（基于交联环糊精）是纳米管膜和生物纳米通道的良好模型体系。这些纳米管内探针分子的核磁共振扩散测量将提供传统技术无法实现的重要见解。工程织物为（生物）化学分离中不混溶流体的液-液接触提供了一种新颖且高度可扩展的方法。该技术的发展需要多相流输运测量和三维两亲微通道孔隙结构表征。（四）拓扑复杂流体中的动力学——由于非常规缠结的存在，相对于线性聚合物，人们对环状和多环状大分子的扩散知之甚少。研究这些拓扑复杂的大分子与线性聚合物共混物的扩散行为将是揭示分子拓扑结构对聚合物动力学基本方面影响的关键。(v)阴离子交换膜中的运输-正在开发采用阴离子交换膜的燃料电池设计，以克服现有质子交换膜的缺点。为了优化这些膜，必须研究氢氧化物离子和水在非均相阳离子聚合物膜中的扩散。更广泛的影响：核磁共振扩散配件将使研究对化学加工和能源管理等领域具有变革潜力的材料、工艺和技术的开发和理解至关重要。无机和有机纳米管、廉价织物基微接触器和阴离子交换膜方面的重大突破可能对经济发展产生广泛影响。拟议的设备是一笔适度的投资，对于在所有这些领域进行探索性研究至关重要。高风险高回报?领域，并提供独特的跨学科杠杆。所要求的设备将大大提高大亚特兰大地区各领域大批研究人员的一般研究能力。

1142111LeisenThe objective of this Early-Concept Grant for Exploratory Research (EAGER) project is to investigate molecular-level transport of (i) reactant species in soups that generate functionalized nanotubes, (ii) probe molecules in designed nanotubes, (iii) fluids in engineered micro-contacters, (iv) macromolecules with multicyclic topologies, and (v) anions in anion exchange fuel cells. These studies will be conducted by diffusion nuclear magnetic resonance (NMR) using specialized equipment acquired with support from this grant (high-gradient-strength diffusion probe and gradient amplifier) on an existing NMR spectrometer. The resulting new experimental capabilities are urgently needed to enable exploratory research in fluid dynamics, separations, nano- and microfluidics, nanoengineering, energy conversion, and fuel cell development. The intellectual merit of the proposed activity is embodied in the research thrusts for which strong-gradient NMR diffusion measurements are needed:(i) Mechanistic studies of nanotube growth and engineering -The requested NMR accessories will enable measurements of size and structure of nanoparticles, thus yielding significant insight into growth mechanisms of single-walled inorganic nanotubes prepared in aqueous solution. This knowledge is crucial for the development of nanotubes, which find applications in various transformational technologies such as electronics, separations and energy storage/generation/ management.(ii) Transport in nanotubes - Nanofluidic transport in tubular materials is poorly understood, in spite of its scientific and technological relevance. Inorganic nanotubes (based on metal oxides) and organic nanotubes (based on crosslinked cyclodextrins) are good model systems for nanotube membranes and biological nanochannels. NMR diffusion measurements of probe molecules within these nanotubes will provide important insights that cannot be achieved with conventional techniques. (iii) Hierarchically engineered fabrics for large-array micro-contactors Engineered fabrics provide a novel and highly scalable approach to liquid-liquid contacting of immiscible fluids for (bio)chemical separations. Development of this technology requires transport measurements of multiphase flow and characterization of pore structure in 3D amphiphilic microchannels.(iv) Dynamics in topologically complex fluids - Diffusion of cyclic and multicyclic macromolecules is poorly understood relative to linear polymers due to the existence of unconventional entanglements. Investigation of the diffusion behavior of blends of these topologically complex macromolecules with linear polymers will be key in unraveling the effect of molecular topology on fundamental aspects of polymer dynamics.(v) Transport in anion exchange membranes - Fuel cell designs that employ anion exchange membranes are being developed to overcome shortcomings of existing proton exchange membranes. Diffusion of hydroxide ions and water confined in cationic polymer membranes with heterogeneous morphologies must be studied in order to optimize these membranes.Broader Impacts: The NMR diffusion accessories will enable research that is critical for development and understanding of materials, processes and technologies with transformative potential in areas like chemical processing and energy management. Important breakthroughs with inorganic and organic nanotubes, inexpensive fabric-based micro-contactors, and anion exchange membranes could have broad implications for economic development. The proposed equipment is a modest investment that is critical for enabling exploratory research within all of these ?high-risk high-payoff? areas and provides unique interdisciplinary leverage. The requested equipment will significantly enhance the general research capabilities of a large group of researchers across a variety of fields in the greater Atlanta area.