| Abstract
| - The potential of diffusion-ordered 2D NMR spectroscopy (DOSY) for the analysis of solutionsof polymer mixtures and polymers with complex molecular mass distributions is investigated. Diffusioncoefficient labeling in NMR is generally achieved by stepwise ramping up of the amplitudes of pairs ofpulsed field gradients (PFGs). After Fourier transformation in the acquisition dimension and an inverseLaplace transform (ILT) with respect to the square of the gradient strength, 2D spectra are obtainedthat show the chemical shift along one dimension and the translational diffusion coefficient along theother. Since polymers may have broad, nonsymmetric or complex (bi- and multimodal) molecular weightdistributions (MWDs), the diffusion coefficient distribution should follow the main features of the MWD.However, the calculation of the diffusion coefficient distribution involves a numerically unstable datainversion (ILT), which limits the resolution in the diffusion dimension. The applications of DOSY NMRtechniques to the study of polymer blends and for the determination of MWDs of polymers with PFGNMR are assessed. DOSY spectra recorded from industrial polypropylene and polystyrene samples andmixtures are shown and interpreted to illustrate the features of this technique.
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