Peroxidic perfluoropolyether from tetrafluoroethylene oxidation: micro structural analysis by NMR spectroscopy and mechanistic considerations

The oxypolymerization reaction of perfluoro olefins is one of the industrial routes for the synthesis of perfluoropolyethers (PFPEs). The distinctive feature of this radically initiated process is that one obtains peroxidic perfluoropolyethers from the oxypolymerization reaction. In the particular case of tetrafluoroethylene (TFE), due to the high reactivity of the olefin, it is possible to obtain peroxidic polymers with variable amounts of peroxide units. It is, therefore of great interest to know in detail the micro structure of this peroxidic polymer with 19F and 13C NMR spectroscopy by far the most suitable techniques for the analysis. A recent investigation on samples with variable peroxide content using a 400 MHz instrument allowed a significant improvement in the analysis of the peroxidic sequences. The results have been discussed in terms of reaction mechanism and kinetics.