Molecular level structure and dynamics of hydrated materials studied by NMR and IR spectroscopy

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The structural and dynamic properties of water within hydrated materials play a key role in how materials function. Hydrated solid matrices such as the polymers used in fuel cells, biological macromolecules found in connective tissue, and hydrated clays in the tailings ponds of northern Alberta owe many of their functional properties to the interaction of water with the material. Developing new techniques and methodologies for studying water at the molecular level is an important part of controlling hydrated material properties for specific applications.In the past six years, undergraduate researchers in my group have developed various multiple quantum filtering techniques to allow us to measure the residual quadrupolar coupling and spin-spin, T2, relaxation, using 2H nuclear magnetic resonance (NMR) spectroscopy. These parameters help clarify the local structure of water and how the molecules move from region to region within the material. Our proposed research extends these studies, incorporating other spectroscopic techniques to complement our current methods. We will harness infrared spectroscopy to better understand hydrogen bond networks, field-cycling NMR relaxometry to provide a more complete picture of water dynamics, and 17O NMR spectroscopy to further unravel the structural and dynamic properties of water. Using this suite of techniques we will expand our understanding of the hydration properties of important materials. Specifically, we will study newly developed hybrid membranes created by adding copolymers, reinforcement layers, and inorganic components to polymer electrolyte membranes used in fuel cells. These additives are intended to increase the operating temperature range of the fuel cells and limit cross-over of fuel species, (e.g. methanol cross-over in methanol fuel cells) leading to higher fuel cell performance. We are interested in how these modifications affect water behavior in the membranes over a range of hydrations and temperatures. Secondly, the students and I will continue our important work of connecting the multiple quantum filtered NMR signal obtained from spinal disc tissue to specific biomarkers, providing magnetic resonance based techniques for early diagnosis of degenerative disc disease. Our success with collagen has shown us the value of looking at individual macromolecular components of the tissue and the next step will involve the study of aggrecan and elastin to determine their contributions to restricted water motion in tissue. Finally, we will use our ability to study water to assist local industries better understand water-clay interactions and help develop techniques that can provide more detailed molecular level information on specific tailings pond samples.