2D NMR analysis of poly(vinyl chloride) microstructure.

One- and two-dimensional heteronuclear H-1 - C-13 and homonuclear H-1 NMR experiments have been examined for their usefulness in establishing stereochemical sequence assignments in poly (vinyl chloride). Correlation via the H-1 - C-13 coupling leads to increased resolution in both the proton and carbon spectra and stereosequence assignments may be made by inspection of the 2D map. Homonuclear correlation via three bond scalar coupling (COSY) may be used to make some of the stereochemical assignments based on the proton data alone. Differences in the magnitudes of the coupling constants may be exploited to uniquely define some of the stereochemical spin systems by utilizing the correlations via double-quantum coherences. Longer range correlations (relayed coherence transfer) define larger segments of the polymer back bone. These studies show that many of the techniques developed for small molecules are applicable to polymer systems and the complete stereochemical resonance assignments may be obtained by the utilization of a number of 2D experiments.