Electron spin resonance studies of peroxy radicals labeled with $sup 17$O in polytetrafluoroethylene
The ESR spectrum of the radicals formed by the reaction of oxygen with $gamma$-irradiated polytetrafluoroethylene (PTFE) has been obtained using oxygen isotopically labeled with $sup 17$O. The presence of lines from two oxygen nuclei both labeled with $sup 17$O confirms that peroxy radicals are formed. Two types of peroxy radicals are discussed; firstly, the peroxy chain radical (-- CF$sub 2$--CF(O$sub 1$$O$$sub 2$) --CF$sub 2$) with g/sub perpendicular/=2.0220, g/ sub parallel/=2.0060, a/sub parallel/(1) =40+-1 G, a/sub parallel/(2) =89+-1 G at 300 K, and g/subz//subz/=2.0380, g/suby//suby/=2.0065, g/subx//subx/=2.0026, a/ subx//subx/(1) =46+-1 G, a/subx//subx/(2) =107+-1 G at 77 K and secondly, the peroxy propagating radical (--CF$sub 2$--CF$sub 2$(O$sub 1$$O$$sub 2$)) with g/sub iso/=2.004, a/sub iso/(1) =13+-1 G, a/sub iso/(2) =26.5+-1 G at 300 K and identical parameters to the peroxy chain radical at 77 K. The temperature dependence of the ESR spectra is analyzed in terms of the rotational freedom in the polymer. The peroxy chain radical undergoes rotation along the polymer chain axis and the peroxy propagating radical also has this rotation about the chain axis and in addition rotates about the C--O bond which is nearly perpendicular to the main chain axis. (AIP)
- Research Organization:
- Institut de Recherches sur la Catalyse, CNRS, 69626, Villeurbanne and Laboratoire de Chimie des Solides, Universite de Paris VI, 75230 Paris Cedex 05, France
- NSA Number:
- NSA-33-028553
- OSTI ID:
- 4065175
- Journal Information:
- J. Chem. Phys., v. 64, no. 6, pp. 2370-2374, Journal Name: J. Chem. Phys., v. 64, no. 6, pp. 2370-2374; ISSN JCPSA
- Country of Publication:
- United States
- Language:
- English
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