Special Issue "NMR in Materials Science"

Guest Editor
Dr. Ulrich Scheler
Department Polyelectrolytes and Dispersions, Leibniz-Institut für Polymerforschung e.V., Hohe Straße 6, 01069 Dresden, Germany
Website: http://www.ipfdd.de/Dr-Ulrich-Scheler.134.0.html?&L=0
E-Mail: Scheler@ipfdd.de
Interests: solid-state NMR; diffusion and electrophoresis NMR; rheological NMR; low-field NMR; polymers; polyelectrolytes; composite materials

Dear Colleagues,

Nuclear magnetic resonance is a versatile tool for the characterization of structure, order an dynamics. The strength of NMR comes from the local nature of the underlying interactions and its high selectivity. Therefore it is equally suited for highly ordered and disordered materials or amorphous materials. Methods are equally applicable to organic and inorganic materials or even organic-inorganic hybrid materials. Numerical methods play an increasing role in the design of new pulse sequences, excitation and decoupling schemes. The combination with the calculation of NMR parameters from quantum chemical calculations permits structure refinement and the so-called NMR crystallography. Recent developments aim for improvement of resolution and sensitivity. The improvements in sensitivity enable new experiments, which had not at all been considered. This special issue will provide the opportunity to present both the latest methods developments and exciting applications.

Dr. Ulrich Scheler
Guest Editor

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• NMR in materials science
• high-resolution solid-state NMR
• structure determination
• NMR crystallography
• relaxometry
• molecular dynamics

Title: Hyperpolarized Xenon Nmr of Building Stones Materials
Authors: Roberto Simonutti and Michele Mauri
Affiliation: Department of Materials Science, University of Milan-Bicocca, Via R. Cozzi 53, I-20125 Milan, Italy; E-Mail: roberto.simonutti@mater.unimib.it (R.S.)
Abstract: The development of optically pumped xenon NMR, that exploits the diffusion of highly nuclear spin-polarized xenon gas on the sample, kicked off completely new fields of applications for xenon NMR: from hyperpolarized biosensors to lung imaging, from combustion studies to the characterization of single crystal surfaces However, porous systems like stones and rocks are still scarcely studied by HP ¹²⁹Xe NMR, expect few cases regarding the characterization of permeability and porosity of reservoir rocks. In fact rocks are very complex systems constituted by several minerals and characterized by a porosity ranging from the microscale to the macroscale, sometimes also containing paramagnetic systems. On the other hand, many types of rocks are used as building materials, sometimes very valuable, like travertine, granite or marble. The characterization techniques currently used for these materials, like SEM and mercury intrusion porosimetry, require a long and delicate preparation; thus, in theory, HP ¹²⁹Xe NMR could provide an alternative method for a quick characterization, especially if we can perform experiments directly on a macroscopic single piece of stone. Here we present continuous flow HP ¹²⁹Xe NMR spectra of several building stones. Marbles like Carrara or Candoglia cause only a broadening of the line width of the free gas resonance but no specific signals. Instead, granites (Serizzo, Beola Verde, Beola Monte Rosa) give rise to characteristic peaks at positive and negative values of chemicals shift. The different behaviours will be explained considering the texture of the stones and the presence of accessible magnetic minerals or phyllosilicates.

Title: Identification of Heterogeneous Coordination Environments in Lithium-Neutralized Ionomers Using Solid State ¹H and ⁷Li MAS NMR
Authors: Todd M. Alam and Janelle Jenkins
Affiliation: Department of Nanostructured and Electronic Materials, Sandia National Laboratories, Albuquerque, NM 87123, USA; E-Mail: tmalam@sandia.gov (T.M.A.)
Abstract: The carboxylic acid proton and the lithium coordination environments NMR for a series of precise polyethylene acrylic acid copolymers and Li-neutralized ionomers were investigated using high speed solid state ¹H and ⁷Li MAS. While the ⁷Li MAS NMR reveals only a single Li environment, the chemical shift was found to be dependent on the spacing between the pendant carboxylic acid groups along the polymer backbone. In addition, two distinct carboxylic acid proton environments were observed at low neutralization levels using 1H MAS NMR. By utilizing ¹H-⁷Li MAS REDOR NMR experiments it is demonstrated that these different proton environments correspond to un-neutralized carboxylic acid groups that have significantly different ¹H-⁷Li coordination distances. These solid state NMR results demonstrate that the acid coordination environments is highly heterogeneous, and that it is important to include this observation in the describing the structure of these ionomer materials.