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ToF‐SIMS observation of PTFE surfaces modified by α‐particle irradiation
Author(s) -
Fisher Gregory L.,
Ohlhausen James A.,
Wetteland Christopher J.
Publication year - 2005
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.2068
Subject(s) - irradiation , degree of unsaturation , chemistry , polymer , branching (polymer chemistry) , fragmentation (computing) , analytical chemistry (journal) , polytetrafluoroethylene , ion , x ray photoelectron spectroscopy , particle (ecology) , secondary ion mass spectrometry , polymer chemistry , materials science , chemical engineering , chromatography , organic chemistry , nuclear physics , physics , oceanography , computer science , engineering , geology , operating system
The surface structure of polytetrafluoroethylene (PTFE) upon α‐particle irradiation has been investigated at doses in the range of 1 × 10 7 to 1 × 10 11 Rad and compared with the surface structure of the unirradiated polymer. Both neat and 25% fiberglass content PTFE were studied. The samples, maintained at nominal room temperature, were irradiated in vacuum by 5.5 MeV 4 He 2+ ions generated in a tandem accelerator beam line. Static time‐of‐flight SIMS (ToF‐SIMS) was employed to probe chemical changes at the surface as a function of the irradiation level. In general, the data are indicative of increased cross‐linking at α‐ doses less than 1 × 10 9 Rad, followed by increased fragmentation and unsaturation at α‐ doses greater than 1 × 10 9 Rad. Throughout the irradiation regime, scission is a constant factor promoting cross‐linking, branching, and unsaturation. However, at α‐doses greater than 1 × 10 10 Rad, extreme structural degradation of the polymer becomes evident and is accompanied by conversion to oxygen‐functionalized and aliphatic compounds. Thus, for PTFE in an α ‐particle field, an upper exposure limit of ∼10 10 Rad is essential for nominal retention of molecular structure. Finally, a quantitative relationship between α‐ dose and characteristic fragment ion intensity is developed. Copyright © 2005 John Wiley & Sons, Ltd.