A Solid State 13C NMR Study of Oligomeric and Polymeric Azines
William B. Euler, James E. Roberts, Macromolecules, 1989, 22, 4221 – 4225
Abstract
The solid-state 13C NMR spectra of a series of oligomeric and polymeric azines based on the 2,3-butanedione dihydrazone monomer have been obtained. The monomer in the series yields single peaks in the methyl region and in the imine region of the NMR spectrum. As the chain length increases, new lines grow in downfield of the monomer resonances while the intensity of the original peaks diminish. This is consistent with the new features being associated with carbons along the interior of the macromolecular chain and the original peaks being associated with carbons at the end of the polymer chain. The downfield shift affiliated with the interior carbons is indicative of a small amount of conjugation in the π system along the chain. The polymer undergoes an irreversible transition in the DSC near 130 °C that has been identified by IR spectra with loss of occluded DMSO from the polymer lattice. Solid-state NMR spectra are consistent with this conclusion.