Advanced NMR Studies of Fluoropolymers Peter L. Rinaldi , University of Akron, DMR 0905120

1. C B Z A Advanced NMR Studies of FluoropolymersPeter L. Rinaldi, University of Akron, DMR 0905120 Model Structure for Krytox® Fluoropolymer • Advanced 19F 2D-NMR (two dimensional nuclear magnetic resonance) techniques are being used to the study the structures of Krytox® fluoropolymers and model compounds for their structures. • Spectral data from a model structure for Krytox® are shown to the right. • Standard COSY (correlation spectroscopy) 2D-NMR methods which use square radiofrequency pulses, produce spectra with a mass of overlapping peaks (a), which are not interpretable. In this panel, two clusters of peaks labeled B2-C1 and A2-B1 are shown. • We have adapted 2D-NMR methods using pulses having complicated shapes to accomplish selective excitation. • These methods produce extremely high resolution spectra with sharp signals and greatly simplified peak patterns. • A sample spectrum is shown in panel (b) to the right. Here, 8 sets of peaks are resolved, 4 in the B2-C1 region, and 4 in the A2-B1 region. • These simplified peak patterns are easily interpreted by NMR specialists, and tell us how the structure units are attached.. • When data is examined from a series of spectra like this, information about a fluoropolymer’s chemical structure can be obtained. • This structure information guides synthetic chemists to make materials with useful chemical and physical properties. B2-C1 B2-C1 (a) Standard COSY 2D-NMR A2 B1 B2 C1 A2-B1 A2-B1 (b) Modified ECOSY 2D-NMR

2. Advanced NMR Studies of FluoropolymersPeter L. Rinaldi, University of Akron, DMR 0905120 Krytox®-PFPE (perfluoro[poly alky ethers]) is a homopolymer of hexafluoro-propylene oxide. Since its first introduction,, it and other PFPEs have found extensive applications as lubricants, sealants and protective coatings in chemically demanding environments, at high temperatures, and as lubricants where hydrocarbon lubricants fail prematurely. It is useful in aerospace applications where it is exposed to extreme conditions of temperature, pressure and chemically reactive species. This class of materials is used as lifetime lubricants for the head-disk interface in magnetic recording media and in bearings for aerospace applications. For these reasons, its chemical structure is of particular interest.