ELECTRON-BEAM-INDUCED DEGRADATION OF POLY(PERFLUOROETHERS) AND POLY(OLEFIN SULFONES)

G values are reported for a variety of poly(perfluorinated ethers) when exposed in a vacuum system to a 25-kV electron beam. The G values for polymer decomposition ranged from 0.1 to 1.2 depending upon the polymer structure and irradiation temperature and were generally higher for polymers containing perfluoromethylene oxide comonomer units compared to perfluoroethylene oxide and perfluoropropylene oxide units. Activation energies for polymer decomposition were obtained from temperature-dependent electron beam irradiation studies using specular reflectance infrared spectroscopy. Values of about 1 kcal/mol are obtained for the poly(perfluoroethers) and 6.8 kcal/mol for poly(2-methylpentene 1-sulfone), respectively. The beta-scissioning reaction in poly(perfluorinated ether) radicals which leads to evolution of COF2 were investigated using ab initio calculations at the 6-31G* level of theory. The calculations predict a DELTAH at room temperature of almost-equal-to 1.2 kcal/mol. Alternative chain scissioning pathways are investigated also.