Chain-End Functionality: The Key Factor toward Fluoropolymer Thermal Stability

The aqueous radical homopolymerization of vinylidene fluoride (VDF), as well its copolymerizations with hexafluoropropylene (HFP) or perfluoromethyl vinyl ether (PMVE), and terpolymerization HFP PMVE, initiated by trifluoromethyl radicals (•CF3), generated from the ammonium persulfate (APS) potassium sulfinate (CF3SO2K) redox system are presented. optimization experimental conditions in terms initial reactant molar ratios, temperature, reaction time was achieved. best results were obtained at 60 °C, water, without any surfactant, using 0.9 equiv APS oxidant respect to CF3SO2K. PVDF, poly(VDF-co-HFP), poly(VDF-co-PMVE), poly(VDF-ter-PMVE-ter-HFP) copolymers high yields (varying between 89 100%) masses up 113,000 g/mol. 1H 19F NMR spectroscopies revealed that, under optimized conditions, formed chain ends exclusively CF3 CF2H. influence nature end on thermal stability showed that PVDFs terminated more stable than their analogues bearing sulfate groups 120 °C. In addition, prepared CF3-PVDFs had 53% crystallinity (compared 47% for PVDF alone), which offers excellent resistance conventional organic solvents including dimethyl sulfoxide, acetone, formamide.