Advanced solid-state NMR techniques exploiting 'H spin diffusion are described,which rely on selecting 'H magnetization of one of the components on the basis of 'H chemical shift or mobility differences under multiple-pulse irradiation. To monitor the progression of 'H spin diffusion, the higher resolution of I3C CP MAS spectra is exploited for NMR detection. For evaluation ofthe data,full quasi-analytical solutions ofthe diffusion equation as well as initial-rate approximations are derived, applied, and discussed. In order to obtain quantitative results, the 'H spin-diffusion constant has to be determined. To this end, the domain sizes in poly(styrene)-poly(methy1 methacrylate) systems including symmetrical diblock copolymers have been measured. The comparison of the NMR results with SAXS and TEM data yields the spin-diffusion coefficient for PS and PMMA.The resulting value ofD=0.8 nm2/ms is expected to be typical for rigid organic systems.The domain sizes investigated range from approximately 1 nm to ca. 100 nm. Bestimmung der DomanengroJen in heterogenen Polymeren mittels Festkorper-NMREs werden moderne Festkorper-NMR-Methoden beschrieben, die 'H-Spindiffusion ausnutzen und 'H-Magnetisierung einer der Komponenten des Systems auf Grund unterschiedlicher chemischer 'H-Verschiebung oder von Mobilitatsunterschieden bei Multipuls-Einstrahlung selektieren.Um die zeitliche Entwicklung der 'H-Spindiffusion zu ermitteln,wird fur den NMR-Nachweis die hohere Auflosung der "C-CP-MAS-Spektren ausgenutzt. Zur Auswertung der Ergebnisse werden vollstandige quasi-analytische Losungen der Diffusionsgleichung sowie Naherungen fur kurze Zeiten abgeleitet, angewendet und diskutiert. Um quantitative Ergebnisse zu erhalten, mu6 die 'H-Spindiffusionskonstante bestimmt werden. Zu diesem Zweck wurden die DomanengroRen in Poly(styren)-Poly(methylmethacry1at)-Systemen, einschliefllich symmetrischer Diblockcopolymere, gemessen. Ein Vergleich der NMR-Ergebnisse mit Rontgenkleinwinkelund elektronenmikroskopischen Daten ergibt als Wert des Spindiffusionskoeffizienten fur PS und PMMA D=0.8 nm2/ms, der als typisch fur starre organische Systeme angenommen werden darf. Die untersuchten DomanengroIJen liegen im Bereich von etwa 1 nm bis 100 nm.

A novel version of the two-dimensional heteronuclear experiment, achieving wideline separation (WISE), is presented. It allows for the correlation of mobility and structure in organic solids.Differences of molecular dynamics are probed by wideline shapes, which are separated in the second dimension by 13C chemical shifts. With a mixing time inserted before cross polarization from to 13C, spin diffusion allows one to determine the mobility at interfaces and to measure domain sizes approximately. The technique is demonstrated on poly(styrene)-poly(siloxane) block copolymers and on a blend of polystyrene) and poly(vinyl methyl ether), where nano-heterogeneity with respect to the mobility is found. The detection of phenyl flips in glassy polymers is also demonstrated.

Stiff macromolecules with flexible side chains are investigated by proton spin diffusion experiments with 13C detection and by a recently developed wideline separation 2D lH-13C NMR experiment (WISE-NMR spectroscopy). The conformational order and the molecular mobility of the alkyl side chains (CieHsa) are characterized for samples with polyester, polyamide, and polyimide main chains. The side chains, which are phase-separated from the main chain in a layer-type structure, can form crystalline as well as amorphous phases. The sizes of these domains depend on the nature of the main chains and their organization.In the polyimide and the polyester with regular main-chain packing, crystalline as well as amorphous regions are observed extending over more than one layer spacing. The heterogeneity observed in the polyamide is only of the order of the layer spacing. The polyester can also be obtained in a modification with uniformly ordered but anisotropically mobile side chains and conformationally disordered main chains. These results indicate coupling between the main-chain and side-chain packing in the investigated stiff macromolecules with flexible side chains.

The miscibility of two high-performance polymers, an aromatic poly(ether-imide) and a poly(aryl4ter-ketone), was investigated by a novel combination of solid-state NMR techniques. This involves a new type of selection of 'H magnetization based on chemical shift differences, 'H spin diffusion during the mixing time and high-resolution I3C detection. Mixing of components on a molecular scale is proved directly.

The use of 13C NMR spectroscopy to study the biosynthesis, degradation and physical properties of polyhydroxyallkanoates (PHAs) is described. Solution‐state NMR of whole cells allows direct observation of biosynthetic pathways within the cell and demonstrates that the bulk of the polymer is in a remarkably fluid, amorphous state. A new model is proposed for the maintenance of this state in vivo: the known rate of crystal nucleation combined with the physical dimensions of the native PHA granule lead naturally to the conclusion that polymer morphology is under kinetic rather than thermodynamic control. Finally solid‐state NMR studies of isolated PHAs allow observation of separate crystalline regions based on hydroxybutyrate and hydroxyvalerate and measurement of the HB and HV contents of these and amorphous domains.

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A 3C solid-state NMR study of two hydrogen-bonded carboxylic acid-pyridyl complexes is presented. The complexes are formed between 4-pentyl benzoic acid (PH complex) in one case and 4-pentyl cyclohexanoic acid (CH complex) in the other and 1,2-bis-(4-pyridyl)ethane. Two different two-dimensional NMR techniques are employed to analyse the motion of the alkyl regions of these two complexes. One technique separates the 13C chemical shift anisotropy powder lineshapes of each 13C site according to the isotropic 13C chemical shift of that site. Subsequent quantitative analysis of the powder lineshapes indicates that the C, alkyl chain of the PH complex is static on the NMR timescale at 298 K, whilst the C, chain in the CH complex undergoes diffusive rotational motions at the same temperature. A second experiment separates the H dipolar-broadened lines according to the 13C chemical shift of the 13C spins to which each 'H nucleus is bound. The results of this experiment suggest that the C, chain in PH remains fairly static at 373 K, but that in CH undergoes motions of greater amplitude at the higher temperature. These different mobilities can be understood in terms of differences in the molecular packing in the solids. The formation of a liquid-crystalline phase for PH and the lack of such a phase for CH can be understood, at least in part, on the basis of the different mobilities of the two complexes in their solid phases.