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X-ray Photoelectron Spectroscopy Study of Argon-Plasma-Treated FluoropolymersFilms of poly(tetrafluoroethylene) (PTFE) and of a tetrafluoroethylene-perfluoroalkyl vinyl ether (approximately 49:1) copolymer (PFA) were exposed to a radio-frequency argon plasma and then examined by X-ray photoelectron spectroscopy (XPS). The use of fluoropolymer films nearly free of surface hydrocarbon contamination as well as the use of a monochromatized X-ray source for XPS removed two factors contributing to conflicting reports on the effect of exposure time on the fluorine-to-carbon (F/C) and oxygen-to-carbon (O/C) ratios for several Ar-plasma-treated fluoropolymers. Contrary to literature indications, a common pattern was found for PTFE and PFA: a moderate decrease in F/C ratio (from 1.99 to 1.40, and from 1.97 to 1.57, respectively), together with a moderate increase in O/C ratio (from negligible to about 0.10, and from 0.012 to about O.10, respectively) at very short exposures, after which the F/C ratios remained essentially constant on prolonged exposures, while the O/C ratios for PTFE and PFA leveled off at 0.11 and 0.15, respectively. The XPS C(sub 1s), spectra for these polymers exposed to the Ar plasma for 20 min were similar and presented, besides a prominent peak at 292.0 eV (CF2,) and a minor peak at 294.0 or 294.1 eV (CF3), a composite band of four curve-resolved peaks (approximately 285-290 eV) representing various CH, CC, CO, CN, and CF functionalities.
Document ID
19970016432
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Golub, Morton A.
(NASA Ames Research Center Moffett Field, CA United States)
Lopata, Eugene S.
(NASA Ames Research Center Moffett Field, CA United States)
Finney, Lorie S.
(NASA Ames Research Center Moffett Field, CA United States)
Date Acquired
August 29, 2013
Publication Date
July 14, 1994
Publication Information
Publication: LANGMUIR
Publisher: American Chemical Society
Volume: 10
ISSN: 0743-7463
Subject Category
Inorganic And Physical Chemistry
Report/Patent Number
NASA-TM-112668
NAS 1.15:112668
Accession Number
97N71508
Distribution Limits
Public
Copyright
Other

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