Novel characterization of polymers using (129)xenon and (13)carbon NMR spectroscopy

Xenon NMR spectroscopy was used to characterize several complex polymer systems. A plastic high-pressure sample container was constructed to provide a simple and safe means to measure spectra of polymers under elevated pressures of xenon in a solution NMR probe.; Phase separation in blends of EPDM and atactic polypropylene was demonstrated by the presence of two xenon resonances. Xenon NMR was more sensitive to phase separation in this system than was DSC. The chemical shift of xenon was linear with respect to the free volume of the trifunctional network polymer made from polypropylene glycol and tris(p-isocyanato phenyl) thiophosphate. The changes in the chemical shift of xenon provided a measure of the kinetics of the cross-linking reaction of polypropylene glycol and 2, 4 toluene diisocyanate. The chemical shift of xenon was measured as a function of generation number for poly(amidoamine) dendrimers. The chemical shift reached a minimum at generation three and increased at higher generation numbers due to reduced free volume of the dendrimer. In all the polymer systems studied it was also shown that the glass transition temperature can be measured with xenon NMR by observing changes in the xenon linewidth versus temperature.; The cross-linked dental polymer Bis-GMA/TEGDMA was studied using both solution and solid state 13C NMR. Solid state NMR provided an accurate means for measuring the degree of polymerization of the networks by measuring the relative areas of the carbonyl peaks from the polymer and the residual monomers. In situ polymerization of the sample during a solution NMR experiment provided a means to measure the kinetics of the polymerization by measuring the disappearance of the NMR signal.