NMR studies of the thermal degradation of a perfluoropolyether on the surfaces of γ-alumina and kaolinite

Kerri A. Denkenberger, Ruth A. Bowers, A. Daniel Jones, Karl Todd Mueller

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9 Scopus citations


Solid-state nuclear magnetic resonance (NMR) methods are used to follow the thermal degradation of Krytox 1506, a common perfluoropolyether, following adsorption onto the surfaces of γ-Al2O3 and a model clay (kaolinite). The alumina studies are complemented with thermogravimetric analysis (TGA) to follow the degradation process macroscopically. Molecular-level details are revealed through 19F magic-angle spinning (MAS), 27Al MAS, and 19F → 27 Al cross-polarization MAS (CPMAS) NMR. The CPMAS results show the time-dependent formation of probable VI Al(O6-nFn) (n = 1, 2, 3) species in which the fluorine atoms are selectively associated with octahedrally coordinated aluminum atoms. For the alumina system, the changes in peak shapes of the CP spectra over time suggest the early formation of catalytically active degradation products, which in turn lead to the formation of additional perfluoropolyether degradation products. Similar to the alumina system, the kaolinite system also displays new resonances in both the 27Al MAS and 19F → 27Al CPMAS spectra after thermal treatment at 300°C for up to 20 h but reveals a more distinct species at -15.5 ppm that forms at the expense of an initial species (3 ppm), which is in greater abundance at shorter heating times.

Original languageEnglish (US)
Pages (from-to)8855-8860
Number of pages6
Issue number17
StatePublished - Aug 14 2007

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry


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