scholarly journals Recent Advances in Surface Activation of Polytetrafluoroethylene (PTFE) by Gaseous Plasma Treatments

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2295 ◽  
Author(s):  
Gregor Primc
Keyword(s):  
Surface Finish ◽  
Photoelectron Spectroscopy ◽  
Surface Film ◽  
Bond Scission ◽  
Chemical Inertness ◽  
Gaseous Plasma ◽  
Hydrophobic Recovery ◽  
Hydrophilic Character ◽  
Discharge Parameters ◽  
Deep Ultraviolet

Fluorinated polymers are renowned for their chemical inertness and thus poor wettability and adhesion of various coatings. Apart from chemical methods employing somewhat toxic primers, gaseous plasma treatment is a popular method for the modification of surface properties. Different authors have used different plasmas, and the resultant surface finish spans between super-hydrophobic and super-hydrophilic character. Some authors also reported the hydrophobic recovery. The review of recent papers is presented and discussed. Correlations between plasma and/or discharge parameters and the surface finish are drawn and the most important conclusions are summarized. The concentration of oxygen in the surface film as probed by X-ray photoelectron spectroscopy is inversely dependent on the concentration of oxygen in gaseous plasma. The predominant mechanism leading to hydrophilic surface finish is bond scission by deep ultraviolet radiation rather than functionalization with reactive oxygen species.

scholarly journals Defluorination of Polytetrafluoroethylene Surface by Hydrogen Plasma

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2855
Author(s):  
Alenka Vesel ◽  
Dane Lojen ◽  
Rok Zaplotnik ◽  
Gregor Primc ◽  
Miran Mozetič ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Photoelectron Spectroscopy ◽  
Treatment Time ◽  
Synergistic Effects ◽  
Surface Film ◽  
Hydrogen Plasma ◽  
Contact Angles ◽  
Hydrogen Atoms ◽  
Tof Sims ◽  
Discharge Parameters

Defluorination of polytetrafluoroethylene (PTFE) surface film is a suitable technique for tailoring its surface properties. The influence of discharge parameters on the surface chemistry was investigated systematically using radio-frequency inductively coupled H2 plasma sustained in the E- and H-modes at various powers, pressures and treatment times. The surface finish was probed by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The measurements of water contact angles (WCA) showed increased wettability of the pristine PTFE; however, they did not reveal remarkable modification in the surface chemistry of the samples treated at various discharge parameters. By contrast, the combination of XPS and ToF-SIMS, however, revealed important differences in the surface chemistry between the E- and H-modes. A well-expressed minimum in the fluorine to carbon ratio F/C as low as 0.2 was observed at the treatment time as short as 1 s when plasma was in the H-mode. More gradual surface chemistry was observed when plasma was in the E-mode, and the minimal achievable F/C ratio was about 0.6. The results were explained by the synergistic effects of hydrogen atoms and vacuum ultraviolet radiation.

scholarly journals Plasma-Stimulated Super-Hydrophilic Surface Finish of Polymers

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2498 ◽  
Author(s):  
Miran Mozetič
Keyword(s):  
Surface Finish ◽  
Photoelectron Spectroscopy ◽  
Oxygen Plasma ◽  
Polymer Materials ◽  
Oxygen Plasma Treatment ◽  
Hydrophilic Surface ◽  
Capacitively Coupled ◽  
Force Microscopy ◽  
The Stability ◽  
Micrometer Scale

Super-hydrophilicity is a desired but rarely reported surface finish of polymer materials, so the methods for achieving such a property represent a great scientific and technological challenge. The methods reported by various authors are reviewed and discussed in this paper. The super-hydrophilic surface finish has been reported for polymers functionalized with oxygen-rich surface functional groups and of rich morphology on the sub-micrometer scale. The oxygen concentration as probed by X-ray photoelectron spectroscopy should be above 30 atomic % and the roughness as determined by atomic force microscopy over a few nm, although most authors reported the roughness was close to 100 nm. A simple one-step oxygen plasma treatment assures for super-hydrophilicity of few polymers only, but the technology enables such a surface finish of almost any fluorine-free polymer providing a capacitively coupled oxygen plasma that enables deposition of minute quantities of inorganic material is applied. More complex methods include deposition of at least one coating, followed by surface activation with oxygen plasma. Fluorinated polymers require treatment with plasma rich in hydrogen to achieve the super-hydrophilic surface finish. The stability upon aging depends largely on the technique used for super-hydrophilization.

Electrochemical and Spectroscopie Evaluation of Lithium Intercalation in Tailored Polymethacrylonitrile Carbons

1997 ◽  
Vol 496 ◽  
Author(s):  
Kevin R. Zavadil ◽  
Ronald A. Guidotti ◽  
William R. Even
Keyword(s):  
Photoelectron Spectroscopy ◽  
Bound States ◽  
Secondary Ion Mass Spectrometry ◽  
Surface Film ◽  
Lithium Ion ◽  
Irreversible Loss ◽  
X Ray ◽  
The Third ◽  
Secondary Ion ◽  
Voltammetric Measurements

AbstractDisordered polymethacrylonitrile (PMAN) carbon monoliths have been studied as potential tailored electrodes for lithium ion batteries. A combination of electrochemical and surface spectroscopie probes have been used to investigate irreversible loss mechanisms. Voltammetric measurements show that Li intercalates readily into the carbon at potentials IV positive of the reversible Li potential. The coulometric efficiency rises rapidly from 50% for the first potential cycle to greater than 85% for the third cycle, indicating that solvent decomposition is a self-limiting process. Surface film composition and thickness, as measured by x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS), does not vary substantially when compared to more ordered carbon surfaces. Li+ profiles are particularly useful in discriminating between the bound states of Li at the surface of solution permeable PMAN carbons.

Sulfidation and Post-Sulfidatton Reactions on Gallium Arsenide

1992 ◽  
Vol 259 ◽  
Author(s):  
J. Yota ◽  
V. A. Burrows
Keyword(s):  
Thin Film ◽  
Electronic Properties ◽  
Photoelectron Spectroscopy ◽  
Surface Film ◽  
Gaas Surface ◽  
Reflection Spectroscopy ◽  
Infrared Reflection ◽  
Considerable Controversy ◽  
Infrared Reflection Spectroscopy ◽  
Sulfur Containing

ABSTRACTChemical treatment of GaAs with sulfur-containing compounds has been shown to improve GaAs surface electronic properties. There is still considerable controversy, however, regarding the chemical nature of the surface film which results from the sulfidation, and of the basis of the electronic improvement and of the decay in the improved electronic properties with time. We have investigated the surface chemistry of the chemical sulfidation treatment of GaAs with Na2S.9H2O and (NH4)2S. Using surface infrared reflection spectroscopy (SIRS) and x-ray photoelectron spectroscopy (XPS), we have studied the GaAs surface and its behavior with time after such treatments. Results show that both of these sulfidation treatments removed the chemical oxide of GaAs, leaving behind a thin film on the surface. XPS results show that the Ga-O and As-O peaks were removed after treatment and that As-S and no Ga-S peaks were formed. Infrared results show that the film deposited after Na2S.9H2O treatment slowly reacted in air to form sodium carbonate and rhombic sulfur. In addition, this film contains compounds with sulfur-oxygen bonds, which most likely were arsenic sulfate, sulfite, and thiosulfate salts. The film deposited on the (NH4)2Streated GaAs surface was identified as ammonium thiosulfate and slowly decomposed with time. Rinsing with water removed the thin film formed after either sulfidation treatment.

Surface investigation of NiTi rotary endodontic instruments after magnetoelectropolishing

2009 ◽  
Vol 1244 ◽  
Author(s):  
Tadeusz Hryniewicz ◽  
Krzysztof Rokosz ◽  
Ryszard Rokicki
Keyword(s):  
Mechanical Properties ◽  
Photoelectron Spectroscopy ◽  
Surface Film ◽  
Surface Characteristics ◽  
Fatigue Tests ◽  
Digital Data ◽  
Maximum Height ◽  
Metallic State ◽  
Interferometric Method ◽  
Study Results

ABSTRACTThe purpose of the study was to reveal the effects of a new electropolishing process carried out under a constant magnetic field, termed as magnetoelectropolishing (MEP). In this work we investigated Nitinol rotary endodontic instruments by surface and morphology change after MEP. The MEP process greatly affects both surface also mechanical properties like the bending and fatigue resistance.The investigation covered surface interferometry measurements, X-ray Photoelectron Spectroscopy (XPS) studies, and Scanning Electron Microscopy (SEM) with EDAX studies referred to two groups of endodontic instruments: ready-to-use or as-received (AR) files, and magnetoelectropolished (MEP) instruments, in comparison with the instruments surface after a conventional electropolishing (EP). The treated surfaces of NiTi endodontic files were studied by interferometric method in view of getting multiple surface characteristics, together with digital data concerning the arithmetic mean height Sa and the maximum height of scale limited surface Sz.The investigation results obtained have indicated a considerable improvement of MEP surface in comparison with both AR and EP surfaces. Such a surface after MEP reveals several positive features, decreased roughness, elimination of metallic state (here Ni and Ti elements) in the surface film, much enriched with titanium oxides and diminished nickel oxides. The study results show that the contents of Ni compounds is higher after EP (18.3%) than after MEP (10.2%), whereas the contents of Ti compounds is higher after MEP (83.4%) than after EP (76.6%). The total Ti/Ni ratio indicates almost double surpass of titanium over nickel in the surface film after MEP in comparison with the total amount of that ratio after EP.The qualitative investigation of fatigue tests have indicated much better performance of NiTi endodontic file samples after MEP than those related to AR and/or after EP. We have proved that the magnetoelectropolishing process may further modify surface. The following studies are to be directed onto performance and specific mechanical properties of the endodontic files at work.

X-ray Photoelectron Spectroscopy (XPS) Investigation of the Surface Film on Magnesium Powders

2012 ◽  
Vol 66 (5) ◽  
pp. 510-518 ◽  
Author(s):  
Paul J. Burke ◽  
Zeynel Bayindir ◽  
Georges J. Kipouros
Keyword(s):  
Surface Layer ◽  
Photoelectron Spectroscopy ◽  
Focused Ion Beam ◽  
Surface Film ◽  
Ion Beam ◽  
Pure Magnesium ◽  
Atmospheric Conditions ◽  
Magnesium Powder ◽  
X Ray ◽  
Aerospace Applications

Magnesium (Mg) and its alloys are attractive for use in automotive and aerospace applications because of their low density and good mechanical properties. However, difficulty in forming magnesium and the limited number of available commercial alloys limit their use. Powder metallurgy may be a suitable solution for forming near-net-shape parts. However, sintering pure magnesium presents difficulties due to surface film that forms on the magnesium powder particles. The present work investigates the composition of the surface film that forms on the surface of pure magnesium powders exposed to atmospheric conditions and on pure magnesium powders after compaction under uniaxial pressing at a pressure of 500 MPa and sintering under argon at 600 °C for 40 minutes. Initially, focused ion beam microscopy was utilized to determine the thickness of the surface layer of the magnesium powder and found it to be ∼10 nm. The X-ray photoelectron analysis of the green magnesium sample prior to sintering confirmed the presence of MgO, MgCO3·3H2O, and Mg(OH)2 in the surface layer of the powder with a core of pure magnesium. The outer portion of the surface layer was found to contain MgCO3·3H2O and Mg(OH)2, while the inner portion of the layer is primarily MgO. After sintering, the MgCO3·3H2O was found to be almost completely absent, and the amount of Mg(OH)2 was also decreased significantly. This is postulated to occur by decomposition of the compounds to MgO and gases during the high temperature of sintering. An increase in the MgO content after sintering supports this theory.

scholarly journals On the early stages of localised atmospheric corrosion of magnesium–aluminium alloys

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
M. Shahabi-Navid ◽  
Y. Cao ◽  
J. E. Svensson ◽  
A. Allanore ◽  
N. Birbilis ◽  
...  
Keyword(s):  
Magnesium Alloys ◽  
Photoelectron Spectroscopy ◽  
Aluminium Alloys ◽  
Atmospheric Corrosion ◽  
Surface Film ◽  
Pure Magnesium ◽  
X Ray Diffraction ◽  
Precipitation Mechanism ◽  
X Ray ◽  
Film Thinning

AbstractThe surface film on pure magnesium and two aluminium-containing magnesium alloys was characterised after 96 h at 95% RH and 22 °C. The concentration of CO2 was carefully controlled to be either 0 or 400 ppm. The exposed samples were investigated using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and electron microscopy. The results showed that when the alloys were exposed to the CO2-containing environment, aluminium cations (Al3+) was incorporated into a layered surface film comprising a partially “hydrated” MgO layer followed by Mg(OH)2, and magnesium hydroxy carbonates. The results indicated that aluminium-containing magnesium alloys exhibited considerably less localised corrosion in humid air than pure magnesium. Localised corrosion in the materials under investigation was attributed to film thinning by a dissolution/precipitation mechanism.

The Study of Tribological Performance and Surface Film Characterization of Bismuth Dioctyldithiocarbamate

1996 ◽  
Vol 436 ◽  
Author(s):  
Chen Ligeong ◽  
Dong Junxiu ◽  
Chen Guoxu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Friction And Wear ◽  
Iron Sulfide ◽  
Surface Film ◽  
X Ray ◽  
Tribological Behaviors ◽  
Reducing Ability ◽  
Inorganic Species ◽  
Metallic Bismuth ◽  
Block Test

AbstractIn this study, bismuth dioctyldithiocarbamate has been synthesized, and Its tribological behaviors, such as friction-reducing ability, antiwear property and extreme pressure performance have been respectively evaluated with a ring-on-block test rig and a fourball machine. In addition to correlate its tribological behaviors with the film formed on the metallic rubbing surface under boundary lubrication conditions, surface analyses have been conducted to characterize the surface film by means of Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy(XPS) and energy dispersion of X-ray (EDX).Test results show the additive compound can effectively improve the friction and wear of the rubbing couples. On the other hand, EDX confirmed the presence of carbon, oxygen, sulfur, nitrogen, bismuth and iron on the surface; AES revealed their depth distribution of atomic concentration percentages. Whereas XPS further disclosed that the composition of the surface film was composed of organic and inorganic species including iron sulfide and sulfate, metallic bismuth, bismuth oxide and sulfide etc. which are conducive to the reduction of friction and wear.

Molecular Composition and Orientation of Interstitial versus Surface Silicon Oxides for Si(111)/SiO2 and Si(100)/SiO2 Interfaces using FT-IR and X-ray Photoelectron Spectroscopies

2003 ◽  
Vol 57 (6) ◽  
pp. 628-635 ◽  
Author(s):  
Georgia Kandilioti ◽  
Angeliki Siokou ◽  
Vasiliki Papaefthimiou ◽  
Stella Kennou ◽  
Vasilis G. Gregoriou
Keyword(s):  
Thermal Oxidation ◽  
Photoelectron Spectroscopy ◽  
Silicon Oxide ◽  
Surface Film ◽  
Spectroscopic Studies ◽  
Native Oxide ◽  
Hydroxyl Groups ◽  
X Ray ◽  
Ft Ir ◽  
On Chip

This work represents a characterization study of silicon oxide on Si(111) and Si(100) surfaces intended for use as substrates in organic light-emitting diodes (OLEDs) on chip devices. Samples have been prepared using either native oxide formation or thermal oxidation, and they have also been treated for activation of hydroxyl groups on their surface. Both Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) have been used in order to understand the molecular orientation as well as the chemical composition of the various oxide types formed during these different oxidation processes. These spectroscopic studies reveal the formation of two different types of oxides on these substrates. The first type is a thin oxide layer on the surface, whereas the second type, called interstitial, is found deeper in the substrate. Specifically, it was found that the Si(100) substrate forms a randomly oriented interstitial oxide, whereas the presence of a lower quantity but more oriented interstitial oxide was found for the Si(111) substrate. In addition, we report for the first time the position of the impurity oxygen for Si(111) substrates at 1122 cm−1. Finally, in both Si(100) and Si(111) substrates, the thin (<15 Å) silicon oxide layers are oriented and appear to contain silicon atoms of similar oxidation states. In contrast, both the thicker surface film (100 Å) as well as the interstitial oxide produced by the thermal oxidation procedure show random orientation and relative uniformity. Overall these orientation studies clearly show that the formation process of surface oxides in different substrates clearly creates species that are oriented differently with respect to the surface.

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