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Multidimensional 19F NMR Analyses of Terpolymers from Vinylidene Fluoride (VDF)–Hexafluoropropylene (HFP)–Tetrafluoroethylene (TFE)

Twum, Eric B., McCord, Elizabeth F., Lyons, Donald F., Rinaldi, Peter L.
Macromolecules 2015 v.48 no.11 pp. 3563-3576
composite polymers, fluorides, microstructure, nuclear magnetic resonance spectroscopy, spectrometers
The use of multidimensional NMR methods for the characterization of polymer microstructure has been applied to terpolymers from vinylidene fluoride (VDF), hexafluoropropylene (HFP), and tetrafluoroethylene (TFE). By assembling the atomic connectivity information obtained from different multidimensional NMR experiments, selective ¹⁹F–¹⁹F COSY (correlation spectroscopy), ¹⁹F–¹⁹F gradient double-quantum COSY, and ¹⁹F–¹³C gradient heteronuclear single-quantum coherence (gHSQC), among others, the detailed monomer sequence arrangements in the terpolymer were obtained. Obtaining the resonance assignments of the terpolymer was greatly aided by the extrapolation of known resonance assignments from PVDF homopolymer, poly(VDF-co-HFP) copolymer, and poly(VDF-co-TFE) copolymer. A tabulated comparison of the microstructure assignment of resonances from PVDF homopolymer as well as poly(VDF-co-HFP) and poly(VDF-co-TFE) copolymers and the terpolymer is provided. Detailed comparisons of ¹⁹F spectra from 470 and 658.4 MHz spectrometers, revealing the AB patterns present in this terpolymer, are presented and discussed in this paper. The compositions of the comonomers in the terpolymers were calculated with different methods, all of which gave similar values. The percentages of VDF and HFP monomer inversions in the terpolymers were also calculated from the assigned NMR resonances.