Low-temperature post-irradiation polymerization of fluoroolefins in glassy perfluoroalkane matrix

Abstract

The kinetics of post-irradiation polymerization of olefins, such as tetrafluoroethylene (TFE), vinylidene fluoride (VDF), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), and ethylene, in the glassy matrix of branched perfluoroalkane C10F22 (PFA) were investigated by low-temperature calorimetry. An olefin solution in PFA transforms into the glassy or the crystalline state upon cooling to 77 K, depending on the monomer concentrations in the initial monomer-PFA mixture. At monomer concentrations (mol/kg) of ≤ 2.5 (TFE), ≤ 1.7 (HFP), ≤ 1.3 (CTFE), and ≤ 1.3 (VDF) in the initial mixture, the fluoroolefins pass completely into the glassy state. The ability of fluoroolefins to polymerize depends on their physical state, and the effective post-irradiation polymerization in the glassy state occurs in the glass transition region of the sample, reaching a high degree of conversion. Hexafluropropylene irradiated in the glassy state in the PFA matrix at 77 K does not polymerize. By their reactivity in polymerization in the glassy state, the olefins can be arranged in the order: TFE > VDF > CTFE > C2H4 ≫ HFP.