The use of 19F NMR and mass spectrometry for the elucidation of novel fluorinated acids and atmospheric fluoroacid precursors evolved in the thermolysis of fluoropolymers

Fluoropolymers are widely used in industry and consumer products. At the thermal limit of their stability (e.g. >260 °C for PTFE) numerous studies have reported a variety of thermolysis products produced upon polymer breakdown. In the current investigations our objective was to expand the knowledge of these products by advancing the techniques used to obtain their identity. The use of 19F NMR to compliment derivatization with GC-MS has been shown to facilitate the identification of novel fluorinated species, in particular fluorinated acids, that had, until recently, gone previously unreported for the thermal decomposition of fluorinated polymers using traditional techniques. The polymers chosen for the decomposition studies were poly(tetrafluoroethylene), poly(chlorotrifluoroethylene), poly(ethylene-chlorotrifluoroethylene) and poly(tetrafluoroethylene-co-tetrafluoro-ethylene perfluoropropyl ether) which cover the three major classes of industrially produced fluoro-polymer, co-polymer and elastomer. The use of 1D 19F and 2D 19F–19F correlation spectroscopy (COSY) NMR allowed for the observation of polyfluorinated acids and their atmospheric precursors. This in turn allowed the modification of GC-MS procedures to verify these NMR findings. NMR results also showed a plethora of unidentified and previously unreported materials, thermolysis products that await characterization.