High‐Resolution Solid‐State 13 C‐NMR Spectroscopy of Polymers [New Analytical Methods (37)]

Until a few years ago, solid‐state nuclear resonance yielded spectra containing broad lines only. Meanwhile, CP/MAS‐NMR spectroscopy has provided a method which gives narrow nuclear resonance lines from a solid‐state specimen as well. Using this technique, it is now possible to produce spectra of “rare” nuclei ( 13 C, 29 Si, 15 N etc.) which are resolved in terms of chemical structure. The analytical capabilities of NMR spectroscopy can be applied to the solid state: it may be that it is necessary to identify compounds in the solid state because, for example, a solvent would alter the coordination sphere, or that it is desired to monitor chemical reactions in the solid state, for example the baking of an enamel. Where a substance in the solid state is concerned, high‐resolution 13 C‐NMR spectroscopy provides not only information about the chemical structure, but also about the solid state itself. To mention just a few examples, information on the conformation, crystal structure and molecular dynamics, as well as molecular miscibility is given. This opens up a broad spectrum of applications, from a statement concerning the crystal modification of an active substance in ready‐to‐use pharmaceutical preparations, e.g. tablets, to the question of whether two polymers are miscible with one another at a molecular level.