A structural and dynamic study of poly(vinyl alcohol) in the gel state by solid-state 13C NMR and 1H pulse NMR

Abstract

1H pulse NMR and high-resolution solid-state 13C NMR spectra of poly(vinyl alcohol) (PVA) gel were measured to clarify the structure and dynamics of the immobile component of the gel. From 1H pulse NMR experiments, it was found that the T 2 signal is mainly composed of three components. The long T 2 component was assigned to the mobile component which comes from the noncrosslinked region, the intermediate T 2 component corresponds to the intermediate immobile component which comes from the vicinity of the crosslinked region, and the short T 2 component corresponds to the immobile component which comes from the crosslinked region in the PVA gel. From high-resolution solid-state 13C NMR experiments, the mechanism of gel formation was satisfactorily elucidated. Further, dynamic viscoelastic modulus measurements were carried out. These experimental results were satisfactorily explained on the basis of the NMR results.