SYNCHROTRON-RADIATION (5-50 EV) INDUCED DEGRADATION OF FLUORINATED POLYMERS

The photochemistry of solid, free-standing films of poly(tetrafluoroet hylene) (PTFE) and poly(hexafluoropropylene-tetrafluoroethylene) (FEP) was investigated by monitoring the neutral photodesorption products p roduced upon irradiation with synchrotron radiation (5-50 eV). CF3, C2 F5, C3F5, C3F7, and C4F7 were the predominant species observed in the mass spectra of the irradiated polymers. Oligomers at least as large a s 293 amu (C7F12) were also detected. Distinct differences are observe d in the photodesorption yields and time responses of the yields based on the energy of the initial excitation. An edge jump at 22 eV in the photon-stimulated desorption spectra of both PTFE and FEP films is as signed to the ionization of the C(2s) states of the polymers. The ener gy dependence of the photodesorption yields is accounted for by consid ering two separate reaction pathways.