Determination of surface structure and orientation of polymerized tetrafluoroethylene films by near-edge X-ray absorption fine structure, X-ray photoelectron spectroscopy, and static secondary ion mass spectrometry

Journal Article · Mon Feb 01 04:00:00 EST 1993 · Langmuir

DOI:https://doi.org/10.1021/la00026a029· OSTI ID:171445

Castner, D G; Lewis, Jr, K B; Ratner, B D ^[1]; Fischer, D A ^[2]; Gland, J L ^[3]

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1. Univ. of Washington, Seattle (United States)
2. Brookhaven National Lab., Upton, NY (United States)
3. Univ. of Michigan, Ann Arbor (United States)

Films of conventional and radio frequency glow discharge (RFGD) polymerized tetrafluoroethylene (TFE) were examined by ultrasoft X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), and static secondary ion mass spectrometry (SIMS). The polarization-dependent intensity changes of transitions to C-C and C-F {sigma} orbitals in the carbon and fluorine near-edge X-ray absorption fine structure (NEXAFS) spectra revealed different CF{sub 2} chain orientations. The surface region of skived poly(tetrafluoroethylene)(PTFE) was composed of CF{sub 2} chains oriented along the surface striations present in PTFE. XPS confirmed only CF{sub 2} groups were present in the PTFE surface region. Fluorocarbon (FC) films prepared by RFGD deposition of TFE onto substrates placed directly in the visible glow (TFE-I) were randomly oriented. XPS showed the TFE-I films had CF, CF{sub 2}, and CF{sub 3} groups in the surface region. Static SIMS indicated that the TFE-I film surface contained CF{sub 3} and CF{sub 2}F{sub 5} groups. XPS showed the FC films prepared by RFGD deposition of TFE onto substrates placed downstream from the visible glow (TFE-II) contained approximately 90% CF{sub 2} groups. The strong polarization dependence of the C and F NEXAFS spectra of these films indicated the CF{sub 2} groups were aligned in vertical chains on the substrate. Static SIMS and XPS results suggested the outermost surface of the CF{sub 2} chains are terminated with CF{sub 3} groups. For thin (50-500 A) FC RFGD films deposited onto polymeric substrates such as poly(methylmethacrylate) or poly(ethylene terephthalate), fluorescence yield detection XAS could be used to examine the substrate, while XPS, static SIMS, and electron yeild detection XAS could be used to examine the FC overlayer. These results demonstrates the complementary nature of ultrasoft XAS, XPS, and static SIMS for detailed surface structural characterization of polymers. 27 refs., 9 figs., 1 tab.

• Sponsoring Organization: USDOE
• OSTI ID: 171445
• Journal Information: Langmuir, Journal Name: Langmuir Journal Issue: 2 Vol. 9; ISSN LANGD5; ISSN 0743-7463
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
FILMS
MASS SPECTROSCOPY
POLYTETRAFLUOROETHYLENE
SPECTROSCOPY
SURFACES
X-RAY SPECTROSCOPY