2D-NMR Characterization of Sequence Distributions in the Backbone of Poly(vinylidene fluoride-co-tetrafluoroethylene)

作者：Li Linlin; Twum Eric B; Li Xiaohong; McCord Elizabeth F; Fox Peter A; Lyons Donald F; Rinaldi Peter L^*

来源：Macromolecules, 2012, 45(24): 9682-9696.

DOI：10.1021/ma3020307

NMR is a powerful tool to study the microstructures of poly(vinylidene fluoride-co-tetrafluoroethylene), poly(VDF-co-TFE). This study shows that the microstructures in this copolymer can be established completely on the basis of 2D-NMR, in which improved dispersion is achieved by the second dimension (F-19 or C-13 chemical shifts). 2D-NMR has been proven to be extremely effective for identifying the carbon sequence distributions in the polymer main chain. For lower level sequences (3- or 5-carbon sequences), resonance assignments on the basis of one- and two-bond F-19{C-13} gradient heteronuclear single quantum coherence (gHSQC) experiments are in good agreement with assignments obtained by traditional methods. Higher level sequences (7- or 9-carbon sequences), which can not be assigned unambiguously by traditional methods, were determined by F-19-F-19 gradient double quantum correlation spectroscopy (gdqCOSY), which provides F-19-F-19 correlations over 3-5 bonds. A quantitative study was also conducted on the composition of this copolymer. Three different approaches were used to calculate the fraction of TFE and the inversion ratio of VDF units.

• 出版日期2012-12-25