Chemical shift trends in the methylene and a substituent regions of 13C NMR spectra of vinyl polymers have been analyzed in terms of a three-state rotational isomeric states (RIS) model and the g-gauche effect. In this framework, it has been demonstrated that the three sequencing rules observed for poly(propylene) can also be expected to work for many other vinyl polymers. The first two rules, justified in terms of the conformational perturbability of stereosequences, turn out to be respected by a considerable number ofNMRspectra. On the other hand, the same spectral data are in substantial disagreement with the third rule. An explanation is proposed for this breakdown.
Simple trends in the methylene and alfa-substituent regions on NMR spectra of vinyl polymers
MONACO, Guglielmo;
2004-01-01
Abstract
Chemical shift trends in the methylene and a substituent regions of 13C NMR spectra of vinyl polymers have been analyzed in terms of a three-state rotational isomeric states (RIS) model and the g-gauche effect. In this framework, it has been demonstrated that the three sequencing rules observed for poly(propylene) can also be expected to work for many other vinyl polymers. The first two rules, justified in terms of the conformational perturbability of stereosequences, turn out to be respected by a considerable number ofNMRspectra. On the other hand, the same spectral data are in substantial disagreement with the third rule. An explanation is proposed for this breakdown.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
