Understanding functional properties of biological and smart materials

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Nuclear magnetic resonance is a powerful tool for understanding the nanoscale features of materials that are responsible for functional properties. In biological tissues, understanding the mechanisms that give rise to imaging contrast is crucial for applying imaging methods clinically. In new classes of engineered materials, understanding the mechanisms of optical, mechanical, and electrical properties is essential for applying these new materials to real-world problems. This proposal describes research in two areas: biological tissues, and engineered `smart' materials, unified by the vision of developing deep understanding of the relationships between structure, function, and properties to enable applications. In brain tissue, the myelin sheath that insulates nerve axons plays a key role in the transmission of nerve impulses. Non-invasive measurement of the abundance and condition of the myelin is a grand challenge. Surprisingly, the mechanisms that give rise to contrast in some widely used magnetic resonance imaging (MRI) techniques to measure myelin are poorly understood. Our objectives are to: 1) explore the details of the physics of the nuclear spin systems in myelin, 2) adapt methodology from solid-state NMR techniques to the constraints of in vivo imaging, 3) develop new contrast mechanisms to better characterize myelin abundance and health, 4) understand the indirect effects that MRI pulse sequences have on the observable NMR/MRI signals, arising from the "invisible" non-aqueous components in brain. In engineered materials, we will work with several different research groups in order to explain the novel properties of the materials they make, and guide their development and application. These materials include: i) a new class of thermoset polymers that offer a promising path to truly recylable plastics with tunable properties, ii) ionic conducting polymer membranes that will be useful for bidirectional human-computer interfaces, and iii) a new class of hydrogen-bonded liquid crystals that show unique properties such as optical switching and a highly-sought after "blue-phase" that is stable over a large temperature range. For each of these systems, we will combine NMR measurements with novel in situ mechanical, electrical, or optical stimulation in order to reveal the microscopic structures and processes responsible for their useful properties. These studies are essential to guide the development of the materials and their applications. The impact of this research will be felt not only within the fields of the individual projects, where the innovative hybrid NMR methods will provide unparalleled new insights into molecular mechanisms, but also from the synthesis of the results; by learning from the common themes and unique differences of these materials and tissues, we will both broaden and deepen our understanding, enabling rapid advancement of materials and better contrast methods for medical imaging.