Radical Grafting of Tetrafluoroethylene and Vinylidene Fluoride Telomers onto Silica Bearing Vinyl Groups

Radical addition of ω-iodofluorinated telomers was used to modify silica (S 50 ) nanoparticles bearing vinyl groups. These iodo terminated derivatives were either commercially available tetrafluoroethylene telomers, C n F 2 n +1 I with n = 4 or 6, or vinylidene fluoride telomers, C n F 2 n +1 [VDF] m I with m = 6 and 23. These latters were synthesized by radical telomerization of VDF with C n F 2 n +1 I initiated by bis(4- tert -butylcyclohexyl) peroxydicarbonate in high yields (>85%). The resulting nanohybrids were characterized by solid state NMR spectroscopy, elemental analyses and thermogravimetry. A covalent grafting between double bonds and fluorinated iodotelomers was noted. The covering density of fluorinated chains was assessed and reported with respect to fluorinated chain lengths. These nanohybrids exhibited a high thermostability (higher than 400 °C under air), losing less than 10% by weight at 700 °C, and a low surface tension, γ s, from around 15 mN·m –1 to about 44 mN·m –1 for silica.