Photooxidation of cured fluorinated polymers .1. Photooxidation of copolymers of fluorinated olefins and allyl or vinyl ethers

The photooxidation mechanisms of two copolymers of fluorinated olefins and allyl or vinyl ethers are studied. The ether groups that constitute the reactive part of both of the polymers are located on short pendant-chains. For this reason, the scissions due to the oxidation of the material lead to notable quantities of low molecular weight photoproducts that can be lost from the solid matrix by migration. The classical analysis of the evolution of the solid polymer matrix then has to be completed by an analysis of the gas phase formed during irradiation. Unanticipated results are obtained, since it is shown from the identification of the whole oxidation photoproducts that the presence of the fluorine strongly influences both the orientation of the reaction and the photooxidation kinetics. Due to the neighboring fluorine atoms, the methylene groups in a-position of the oxygen of the ether groups are not equivalent regarding oxidation and the secondary carbon becomes more oxidizable than the tertiary one. Moreover, these polymers show a very high resistance towards photooxidation, which is quite unusual with regard to polyethers in general.