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Solid-state NMR has become a powerful tool for studies of structural and physical properties of polymers. This thesis investigates a technically produced block copolymer . by means of solid-state NMR. The properties which are of principal interest are the heterogeneity on various scales ranging from molecular (unit cell) to macroscopic (morphology), and molecular motion in solids. The important question of cross polarisation is addressed. Quantification of depolarisation experiments will bring some more insight into the origins of the polarisation transfer. Basically a model by Muller, Kumar and Ernst has been used to describe the polarisation transfer. Novel results are reported in this area spin-lattice relaxation measurements, both in the laboratory and on-resonance rotating frames of resonance are applied to the block copolymer. An attempt is made to address the relation of the observed relaxation times and the macroscopic properties. The behaviour of the observed and the intrinsic properties of the various regions of the heterogeneous system in the presence of spin diffusion is investigated. The system is simulated by a computer model, which allows quantification of the dimensions of the different regions. Comparison with small-angle X-ray diffraction measurements illustrates the accuracy of this new powerful technique.

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This body of work is tackling some of the challenges in the field of lithium-ion batteries (LIBs) for electric vehicles through in situ nuclear magnetic resonance (NMR). In situ NMR allows for the simultaneous monitoring of both liquid and solid components (electrolyte, cathode, anode, separator) and provides timely data acquisition making it a great method to extract real-time information about structural changes, degradation products and failure mechanisms in batteries. A combined in situ 7Li NMR and ex situ 29Si magic-angle spinning (MAS) NMR study on silicon and silicon monoxide was used to compare structural differences in these anode materials using a custom-made in situ cell. Some key differences between the two materials were obtained, highlighting the importance of in situ NMR to be used for identifying phases, which are not present under ex situ conditions. In addition, fast charging of silicon anodes was investigated to gain a better understanding of their performance at high current rates. Magnetic resonance imaging was also implemented to localize lithium metal deposition under these conditions, which was made possible by a unique in situ parallel-plate resonator setup. Finally, the successful development of a novel in situ MAS NMR technique is introduced, which for the first time allows for an in situ analysis of a LIB under MAS. This strategy paves the way toward acquisition of valuable in situ data on the formation and transformations of metastable states within the active materials of both electrodes; data that is difficult to obtain from static in situ NMR experiments alone. / Thesis / Doctor of Philosophy (PhD)

This PhD thesis presents structural investigations of amorphous inorganic materials: oxide and oxynitride glasses and mesoporous bioactive glasses (MBGs), by solid-state Nuclear Magnetic Resonance (NMR). Lanthanum oxide and oxynitride [La-Si-(Al)-O-(N)] glasses have a large number of potential applications due to their physical properties. In our work we have studied, compared to previous investigations, significantly expanded ranges of glass compositions (for oxynitride glasses, including samples of very high nitrogen content, up to 53 % out of the anions). We have estimated local environments of 29Si and 27Al structural units (their coordination, polymerization degree and number of N incorporated into tetrahedral units) in the materials. We have suggested a random Al/Si distribution along with almost uniform non-bridging oxygen atoms distribution in aluminosilicate glasses. Silicon nitride was used as precursor in the oxynitride glass synthesis. We studied both α- and β-modifications of silicon nitride, 15N-enriched, as well as fully (29Si, 15N)-enriched samples. We have shown that the linewidths of 15N NMR spectra are dominated by J(29Si-15N) coupling in 29Si315N4 sample. Mesoporous bioactive glasses in the CaO-SiO2-P2O5 system show superior bioactivity (the ability to form a hydroxycarbonate apatite layer on the glass surface when exposed to body fluids) compared to conventional bioactive glasses due to their large surface area and uniform pore-size distribution. Previous studies suggested a homogeneous cation distribution over the MBG samples on a 10−20 nm length-scale. From our results, on the other hand, we may conclude that Si and P is not intimately mixed. We propose a structural model, in which the pore walls of MBGs are composed of a silica network, and a phosphate phase is present as nanometer-sized clusters that are dispersed on the pore wall.

High–resolution multidimensional proton-detected NMR was used to study the solvent-exposed regions of a seven-helical integral membrane proton pump proteorhodopsin (PR). Fully deuterated PR samples with protons reintroduced to solvent-accessible sites through back exchange were prepared and found to produce NMR spectra with acceptable proton resolution (~0.2 ppm). Novel three-dimensional proton-detected chemical shift correlation spectroscopy was used for the identification and resonance assignment of the solvent–exposed regions of PR. Though most of the observed residues were located at the membrane interface there were notable exceptions, particularly in helix G. This helix contains the Schiff base-forming Lys231 and many conserved polar residues in the extracellular half. Solvent accessibility of helix G supports the hypothesis that high mobility of the F-G loop could transiently expose a hydrophilic cavity in the extracellular half of PR, and implies that such a cavity may be part of the protein’s proton-conduction pathway. / Natural Sciences and Engineering Research Council, Ontario Ministry of Training, Colleges, and Universities, Canadian Foundation for Innovation, Ontario Ministry of Research and Innovation, University of Guelph

The local information provided by nuclear magnetic resonance (NMR) makes it an ideal method for the structural investigations of materials lacking extended long-range ordering. This work focuses on investigations of two types of materials possessing very different types of disorder. The first section involves investigations of alkali borate glasses and the application of solid-state NMR techniques to probe short- and medium-range ordering in such glasses. Differences between the various alkali borates over a wide compositional range are probed using one and two-dimensional techniques. The use of double-resonance dipolar recoupling techniques to investigate cesium-boron distances is investigated. The second section probes a series of transition-metal cyanide coordination polymers. The bidentate nature of the cyanide ligand allows for the possibility of forming numerous isomers. Information about the isomer(s) present is gained via the various NMR parameters available, such as the chemical shifts, shift anisotropies and J-couplings. This is then extended to the characterization of paramagnetic transition-metal cyanides, where strong electron-nuclear interactions are shown to significantly increase spin-lattice relaxation rates allowing the acquisition of spectra without the need of typically employed enhancement techniques, yet often yielding spectra of better quality. Variable-temperature experiments allow a measure of the electron-nuclear interaction, which can be related to spatial proximity, and provide “diamagnetic” chemical shifts allowing comparison with other cyanides. J-couplings and chemical shift anisotropies are shown to be applicable in much the same fashion as with diamagnetic systems.

The local information provided by nuclear magnetic resonance (NMR) makes it an ideal method for the structural investigations of materials lacking extended long-range ordering. This work focuses on investigations of two types of materials possessing very different types of disorder. The first section involves investigations of alkali borate glasses and the application of solid-state NMR techniques to probe short- and medium-range ordering in such glasses. Differences between the various alkali borates over a wide compositional range are probed using one and two-dimensional techniques. The use of double-resonance dipolar recoupling techniques to investigate cesium-boron distances is investigated. The second section probes a series of transition-metal cyanide coordination polymers. The bidentate nature of the cyanide ligand allows for the possibility of forming numerous isomers. Information about the isomer(s) present is gained via the various NMR parameters available, such as the chemical shifts, shift anisotropies and J-couplings. This is then extended to the characterization of paramagnetic transition-metal cyanides, where strong electron-nuclear interactions are shown to significantly increase spin-lattice relaxation rates allowing the acquisition of spectra without the need of typically employed enhancement techniques, yet often yielding spectra of better quality. Variable-temperature experiments allow a measure of the electron-nuclear interaction, which can be related to spatial proximity, and provide “diamagnetic” chemical shifts allowing comparison with other cyanides. J-couplings and chemical shift anisotropies are shown to be applicable in much the same fashion as with diamagnetic systems.

No description available.