Swift heavy ions effects in fluoropolymers: Radicals and crosslinking

Fluoropolymers are irradiated with different swift heavy ions (O, Kr, Sn) in the electronic stopping power range (2.9 to 7.8 MeV/amu). The stable radicals left after irradiation are analysed by Electronic Spin Resonance (ESR). The nature of the radicals depends mainly on the chemical structure. After recombination of the radicals, a stable radical remains which is not a polyenyl radical and is best seen when ions of high Z and high fluences are used. It is characterized by ESR and consists of an isotropic singlet of lorentzian lineshape. In addition, it does not depend on the chemical composition nor on the nature of the crystalline phase. This new radical is believed to be located in the crosslinked structure where no hyperfine interactions are possible. Solubility measurements are performed and analysed by the Charlesby-Pinner equation. The results are in agreement with this hypothesis.