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NMR Study of the Chain End and Branching Units in Poly(vinylidene fluoride-co-tetrafluoroethylene)

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journal contribution
posted on 24.09.2013, 00:00 by Linlin Li, Eric B. Twum, Xiaohong Li, Elizabeth F. McCord, Peter A. Fox, Donald F. Lyons, Peter L. Rinaldi
2D-NMR techniques were used to identify the detailed structures of chain end and branching units in poly­(vinylidene fluoride-co-tetrafluoroethylene), poly­(VDF-co-TFE). Atomic connectivity information was provided by selective 19F–19F COSY (correlation spectroscopy), 19F­{1H} gHETCOR (gradient heteronuclear correlated), and 1H­{13C} HSQC (heteronuclear single quantum correlation) experiments. Diffusion ordered spectroscopy (DOSY) and spin–lattice relaxation (T1) data permitted distinction of backbone, short chain branch, and chain end resonances from one another. Quantitative data on these structures are reported; quantitation also supported assignments through the consistent relative intensities of resonances from the same structures. Possible reactions during the polymerization which could lead to these structures are discussed.