Characterization of perfluoropolymers using solid state 19F MAS NMR spectroscopy

Abstract

Perfluoropolymers exhibit very unique properties and outstanding functionalities, but the characterization is generally difficult because of their insolubility in organic solvents and their high melting temperatures. 19F magic angle spinning (MAS) NMR has considerable potential for the characterization of chemical structures, morphology, and molecular-level mobility of perfluoropolymers in the solid state. The considerable benefits from the high natural abundance, strong magnetic dipole moment and substantial range of isotropic chemical shifts of fluorine can be utilized because the technical problems that hindered the acquisition of high-resolution 19F spectra with excellent quality have been overcome. In this article, we reviewed solid state 19F MAS NMR studies on poly (tetrafluoroethylene) (PTFE), poly (tetrafluoroethylene-co-hexafluoropropylene) (FEP), perfluoroalkoxy polymers (PFA), a perfluoro-elastomer (Kalrez), a perfluoroamorphous polymer (CYTOP), a perfluoro-ionomer (Nafion), and some perfluoropolymers produced by chemical vapor deposition and some irradiated by γ-ray or electron beams.