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

G values are reported for a variety of poly(perfluorinated ethers) whe n exposed in a vacuum system to a 25-kV electron beam. The G values fo r polymer decomposition ranged from 0.1 to 1.2 depending upon the poly mer structure and irradiation temperature and were generally higher fo r polymers containing perfluoromethylene oxide comonomer units compare d to perfluoroethylene oxide and perfluoropropylene oxide units. Activ ation energies for polymer decomposition were obtained from temperatur e-dependent electron beam irradiation studies using specular reflectan ce 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(perfluor inated ether) radicals which leads to evolution of COF2 were investiga ted using ab initio calculations at the 6-31G level of theory. The ca lculations predict a DELTAH at room temperature of almost-equal-to 1.2 kcal/mol. Alternative chain scissioning pathways are investigated als o.