E. M. O'Connell, Chang-Zheng Yang, T. Root
Aug 26, 1996
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Influential Citations
23
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Journal
Macromolecules
Abstract
Natural-abundance 15N nuclear magnetic resonance (NMR) experiments show direct evidence for metal−pyridine interactions in blends of pyridine-containing polyurethanes and metal acetates. After blending with zinc acetate, the pyridine nitrogen peak shifts from −320 to −304 ppm; blending with magnesium acetate causes a shift to −309 ppm. Sodium acetate did not complex with the pyridine-containing polyurethanes; no shifts in the 13C NMR signal for the acetate carbonyl or in the 15N NMR for the pyridine nitrogen are apparent. Additionally, no interactions were evident for the urethane nitrogen site in any of the blends. Peak shifts, changes in cross-polarization dynamics, and increases in relaxation times were also apparent in the 13C NMR spectra of the metal acetate−polymer blends. Effects of blending on the hard-domain hydrogen bonding were evident in FTIR and 15N NMR contact-time experiments. The N−H stretching band shifted to higher wavenumbers and the 15N NMR N−H signal persisted to longer contact times ...