High-Temperature Pulsed-Field-Gradient Multidimensional NMR of Polymers

The application of pulsed-field-gradient (PFG) techniques has been particularly important in providing the ability to detect 2D and 3D NMR cross peaks from minor structural components in synthetic organic polymers. The lack of mobility in a large percentage of polymers leads to rapid T2 relaxation w...

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Bibliographic Details
Published in:Journal of magnetic resonance (1997) 1999-10, Vol.140 (2), p.482-486
Main Authors: Liu, Weixia, Ray, Dale G., Rinaldi, Peter L., Zens, Toby
Format: Article
Language:English
Subjects:
2D NMR
high temperature
Magnetic Resonance Spectroscopy
polyethylene
polymers
pulsed field gradients
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Summary:The application of pulsed-field-gradient (PFG) techniques has been particularly important in providing the ability to detect 2D and 3D NMR cross peaks from minor structural components in synthetic organic polymers. The lack of mobility in a large percentage of polymers leads to rapid T2 relaxation which prevents the use of pulse sequences, such as the HMBC experiment, that operate based on coherence transfer via small, long-range J couplings. High-temperature NMR increases molecular motion with corresponding line narrowing (e.g., polyethylenes are typically analyzed at 120°C). However, until now, the requirement for high temperature has precluded the use of PFG methods. Here we present data from a new probe which is capable of performing high-temperature PFG coherence selection experiments at temperatures typical of those used in many polymer analyses. We illustrate the performance of this probe with PFG-HMBC spectra of a copolymer from ethylene/1-hexene/1-butene at 120°C.
ISSN:1090-7807
1096-0856
DOI:10.1006/jmre.1999.1868