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

Abstract

2D-NMR techniques were used to identify the detailed structures of chain end and branching units in poly­(vinylidene fluoride-<i>co</i>-tetrafluoroethylene), poly­(VDF-<i>co</i>-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 (<i>T</i>₁) 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