NMR Study of the Chain End and Branching Units in Poly(vinylidene fluoride-<i>co</i>-tetrafluoroethylene)
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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 <sup>19</sup>F–<sup>19</sup>F COSY (correlation spectroscopy), <sup>19</sup>F{<sup>1</sup>H} gHETCOR (gradient heteronuclear correlated), and <sup>1</sup>H{<sup>13</sup>C} HSQC (heteronuclear single quantum correlation)
experiments. Diffusion ordered spectroscopy (DOSY) and spin–lattice
relaxation (<i>T</i><sub>1</sub>) 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