Solid state nuclear magnetic resonance composition

Wilson et al. [2] carried out a compositional and solid state nuclear magnetic resonance (NMR) spectroscopic study of humic and fulvic acid and fractions present in soil organic matter. 

Hoh, K.P., Ishida, H. and Koenig, J.L. (1990). Silicon-29 solid state nuclear magnetic resonance spectroscopy of composite interfaces. Polym. Composites 11, 121 125. 

The enantiomer and the racemic compound possess different crystal structures, which correspond to different intermolecular interactions, as mentioned in Sec. 3. Therefore the enantiomer and the racemic compound exhibit different powder x-ray diffraction (PXRD) patterns, different infrared (IR) and Raman spectra, and different solid-state nuclear magnetic resonance (SSNMR) spectra. However, the opposite enantiomers give identical PXRD patterns, and identical IR, Raman, and SSNMR spectra. Consequently, the PXRD patterns and the above spectra of a conglomerate, which is a physical mixture of opposite enantiomers, are identical to that of the pure enantiomers. In contrast, the diffraction pattern and the various corresponding spectra of the racemic compound usually differ significantly from those of the pure enantiomers. Therefore the type of racemate can be easily determined by comparing the diffraction patterns or the various spectra of the racemic species with that of one of the pure enantiomers (Figs. 3 5). The enantiomeric composition in a racemic mixture may be determined by PXRD, or by IR or SSNMR spectroscopy. Quantitative PXRD has been applied to determine the relative... 

Schaefer et al. (19) studied the interphase microstructure of ternary polymer composites consisting of polypropylene, ethylene-propylene-diene-terpolymer (EPDM), and different types of inorganic fillers (e.g., kaolin clay and barium sulfate). They used extraction and dynamic mechanical methods to relate the thickness of absorbed polymer coatings on filler particles to mechanical properties. The extraction of composite samples with xylene solvent for prolonged periods of time indicated that the bound polymer around filler particles increased from 3 to 12 nm thick between kaolin to barium sulfate filler types. Solid-state Nuclear Magnetic Resonance (NMR) analyses of the bound polymer layers indicated that EPDM was the main constituent adsorbed to the filler particles. Without doubt, the existence of an interphase microstructure was shown to exist and have a rather sizable thickness. They proceeded to use this interphase model to fit a modified van der Poel equation to compute the storage modulus G (T) and loss modulus G"(T) properties. 

Nanostructured Silicon-Based Powders and Composites, ed. A.P. Le-grand and C. Senemaud, Taylor Francis Ltd. London, UK, 2003 R 221 A.P. Legrand and J.-B. d Espinose de la Caillarie and Y. El Kortobi, Chemical Order Studied by Solid-State Nuclear Magnetic Resonance , p. Ill... 

Partial inclusion of small branches in the polyethylene unit cell was confirmed by solid-state nuclear magnetic resonance ( C NMR) [38-40]. It was observed that while methyl groups partitioned into the polyethylene unit cell on an equilibrium basis, the composition of the crystalline phase in copolymers containing longer side groups was dependent on crystallization history. Slow-cooled copolymer samples showed lower degrees of defect incorporation because the crystallite was allowed more time to perfect its order [38]. 

Framework and Surfaces Since compositions and structures are very diverse, surface and framework properties are also extremely varied. In terms of compositions, coordination, and chemical environments, several methods are particularly informative for the characterization of nanoporous solids, such as nuclear magnetic resonance methods (NMR), UV-visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, x-ray absorption spectroscopies, x-ray photoelectron emission spectroscopy (XPS), and electron paramagnetic resonance (EPR) (4, 6). Among them, sohd state NMR techniques arc largely employed and will be briefly described in the following. 

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