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

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

1142111 Leisen The 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.