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Polymer characterization by NMR.

Our research group's main field of research is the theory and applications of nuclear magnetic resonance (NMR), and McMaster is one of the best-equipped chemistry departments for this type of research. The NMR facility has spectrometers for liquid-phase NMR up to 500 Mhz for protons, as well as some capabilities for solid-state NMR. Most modern techniques, such as two-dimensional NMR and inverse detection have been implemented and are being used routinely. NMR is one of the most powerful analytical methods in chemistry, and there are many applications to polymer chemistry.

Much of the polymer work in our group has revolved around solvent-swollen cross-linked polymer gels. Many important polymer systems are cross-linked, since this gives many desirable properties to the material. However, if the cross-linking is high, these polymers become insoluble and many polymer characterization methods can no longer be applied. Solvent-swollen gels of lightly cross-linked polymers are of considerable importance by themselves and they offer an excellent model for studying these important materials. Liquid-like NMR spectra can be obtained, and so fine details can be observed.

Recent work has focused on using the solvent as a probe for what is happening in the gel. In favourable cases we can observe the solvent in the gel and the bulk solvent as distinct signals, so we can look for differences between these two sites and measure how fast solvent comes in and out of the network. This can give us unique information on the architecture of these swollen gels, such as the size of the pores and the density of the cross-links. At the moment, our group is actively pursuing this project.
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Title Annotation:nuclear magnetic resonance
Author:Bain, Alex D.
Publication:Canadian Chemical News
Date:Apr 1, 1991
Previous Article:Monitoring of plasma processes.
Next Article:Polymers for biomedical applications.

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