Polytetrafluoroethylene Target Research Articles

In vitro corrosion behavior of PTFE coating on AZ31 by RF magnetron sputtering for biomedical application

Surface coatings are widely used for improving the biocompatibility or corrosion resistance of Mg alloy implant materials. Polytetrafluoroethylene (PTFE) coating with about 100 nm thickness was prepared on AZ31 alloy substrate by radio frequency magnetron sputtering. The coating was characterized via X-ray photoelectron spectroscopy, fourier transform infrared spectrometer, X-ray diffractometer, scanning electron microscope, contact angle goniometer, atomic force microscope and white light interferometer. The corrosion behavior of PTFE coating were analyzed by electrochemical and immersion measurements in SBF. The results showed that PTFE coating with dense and flat surface can be formed on AZ31 alloy substrate by sputtering a PTFE target directly at room temperature. The corrosion current density declined from 1.92 × 10−4 A/cm2 (bare AZ31 alloy) to 1.07 × 10−8 A/cm2 (sample with PTFE coating), and the 7 days immersion tests revealed a complete surface morphology and very slight variation in pH value of the SBF, suggesting a significant increase in corrosion resistance. High viability rate of endothelial cells of the PTFE coated AZ31 proved the good biocompatibility. These results manifest that the PTFE is a protective coating on magnesium alloys for implants application.

Highly Stretchable, Conductive Polymer Electrodes with a Mixed AgPdCu and PTFE Network Interlayer for Stretchable Electronics

AbstractA highly stretchable, conductive polytetrafluoroethylene (PTFE) electrode consisting of a mixed AgPdCu (APC) and PTFE network interlayer on a polyurethane substrate is fabricated at room temperature. The PTFE/APC‐PTFE/PTFE multilayer deposited through continuous sputtering of carbon nanotubes of the mixed PTFE and APC targets, and the resulting material exhibit a sheet resistance of 33.6 ± 6.17 Ohm per square and a stretchability of 40%. The metallic APC‐PTFE network interlayer provides a conducting path for the PTFE/APC‐PTFE/PTFE multilayer, and it maintains a reversible conductivity until the electrode has been stretched up to 40%. In addition, the sputtered PTFE/APC‐PTFE/PTFE multilayer shows semi‐transparency about 47% in the visible wavelength region. The multilayered material shows a minimal change in resistance after 10 000 cycles of repeated stretching under a constant 20% strain. In addition, the stretchable PTFE/APC‐PTFE/PTFE electrode is confirmed to be resilient outer/inner bending, folding, rolling, and twisting tests. Through successful operation of stretchable interconnectors, stretchable film heaters, and stretchable electroluminescent devices, it is confirmed that sputtered PTFE/APC‐PTFE/PTFE films can be promising stretchable electrodes for next‐generation stretchable electronics.

Plasma Processing with Fluorine Chemistry for Modification of Surfaces Wettability.

Using plasma in conjunction with fluorinated compounds is widely encountered in material processing. We discuss several plasma techniques for surface fluorination: deposition of fluorocarbon thin films either by magnetron sputtering of polytetrafluoroethylene targets, or by plasma-assisted chemical vapor deposition using tetrafluoroethane as a precursor, and modification of carbon nanowalls by plasma treatment in a sulphur hexafluoride environment. We showed that conformal fluorinated thin films can be obtained and, according to the initial surface properties, superhydrophobic surfaces can be achieved.

Thermophysical and spectral features of laser ablation of polymers

The effect of intense laser radiation on polymers depends on many factors; the most important of these factors are the optical properties of the polymer at the emission wavelength and the irradiation mode (continuous or pulsed). In the case of ablation of polytetrafluoroethylene (PTFE) with continuous CO2 laser radiation at a wavelength of 10.6 μm, the initial target temperature and the state of the target microstructure, which is determined by the polymer monolithization mode, are also influencing factors. An increase in the initial temperature of a PTFE target from room temperature to 683 K provides a 2.8-fold increase in the ablation rate and a significant increase in the fiber fraction yield, the quantitative values of which depend on the polymer synthesis and monolithization modes. A tenfold decrease in the emission wavelength to 1.06 μm leads to a multifold decrease in the ablation efficiency of radiation for all polymers; the multiplicity of change in the ablation rate compared to that on a CO2 laser depends on the polymer type.

Adjustable, (super)hydrophobicity by e-beam deposition of nanostructured PTFE on textured silicon surfaces

Polytetrafluoroethylene (PTFE)-like films, produced by electron beam (e-beam) deposition, have shown higher hydrophobicity than those deposited by RF sputtering under similar deposition rates. It was found that this results from both surface chemical composition and nano-roughness. X-ray photoelectron spectroscopy measurements revealed that larger moieties of CF2 and CF3 groups were present to reduce surface energy in the e-beam deposited films. RF sputtering led to a higher degree of PTFE target fragmentation producing a different perfluorinated film on the Si substrate. Scanning electron microscopy and atomic force microscopy measurements revealed a much larger rms roughness on the film surfaces produced by e-beam (25.13 nm, at 20 mA) than those by RF sputtering (2.42 nm, at 100 W), and allowed a broad power spectrum density analysis with determination of the κ B wetting parameter. In addition, the e-beam deposited films presented a linear increase of contact angle with applied electron current in the range under study (5–20 mA). This allows easy water repellency adjustment, up to 159 ± 2°. For a superhydrophobic state with self-cleaning, a micro-pyramid structure was wet etched on the Si wafer, followed by PTFE deposition, and a very low contact angle (163 ± 2°) and hysteresis was attained (<3°). These first results indicate that e-beam PTFE deposition with adjustable hydrophobicity may become a useful technique for integrated production with present Si microelectronics technology and for Si solar cells.

Effect of Preliminary Heating of a Polymeric Polytetrafluoroethylene Target on its Ablation by a Continuous CO2 Laser

We study experimentally the effect of pre-heating polytetrafluoroethylene (PTFE) on its laser ablation rate from a continuous wave CO2 laser. The ablation rate and the fraction of fiber formed grow significantly as the initial temperature of the polymeric target increases from 292 to 683 K. The ablation rate obeys two exponential dependences on the temperature with different apparent activation energies for the high-temperature and low-temperature regimes. We find that a crossover temperature of 460 K correlates best with the temperature for sol–gel transformation in the bulk. The faster rates at higher temperature are due to the ability of the reactive species generated in the ablation process to react with more of the system.

Ion Beam Sputtering Deposition and Characterization of ZnO-Fluoropolymer Nano-Antimicrobials

A new class of nano-antimicrobials was developed by Ion Beam co-Sputtering of ZnO and polytetrafluoroethylene targets. The resulting nanostructured coatings combine the antimicrobial properties of ZnO nanoparticles with the water repellence and anti-stain characters of the dispersing fluoropolymer (CFx). ZnO-CFx nanocomposites with variable ZnO volume fraction ( ) in the CFx matrix were prepared by tuning the sputtering deposition parameters. Morphological analysis confirmed the presence of homogenously distributed ZnO nanoclusters in the polymer. ZnO loadings ranging in the 0.05–0.15 interval were explored and the nanocomposites were characterized by X-ray Photoelectron Spectroscopy (XPS) to investigate their surface chemical composition. XPS spectra evidenced a high degree of polymer defluorination along with the formation of ZnF2 at increasing values. Zn speciation was performed on Zn L3M45M45 Auger signal. Coatings bioactivity was assessed against Escherichia coli, Staphylococcus aureus, and Kluyveromyces marxianus. At ≥ 0.10, ZnO-CFx composites exhibited appreciable antibacterial activity, irrespective of the target organism.

Effects of substrate temperature on structure and mechanical properties of sputter deposited fluorocarbon thin films

Fluorocarbon thin films were formed by radio-frequency magnetron sputtering using a polytetrafluoroethylene target with different substrate temperatures in the range −5 to 200 °C. Using X-ray diffraction and Fourier transform infrared spectroscopy, it was confirmed that the films were amorphous and contained C–F bonds. X-ray photoelectron spectroscopy measurements indicated that the amount of cross-linking in the films increased with increasing substrate temperature. Corresponding to the change in the molecular structure, the adhesion strength of the films to the Si substrate, estimated by micro-scratch testing, improved with increasing substrate temperature.

Titanium–aluminum–polytetrafluoroethylene coated stainless steel micromold via co-sputtering deposition: Replication performance and limitation in hot-embossing

Stainless steel micromold is an alternative of silicon (Si) micromold in the fabrication of polymeric microfluidic devices because of the brittleness and short lifetime of Si mold. High adhesion and friction of stainless steel micromold can cause the distortion of the microstructures of polymeric products. In this work, titanium (Ti), aluminum (Al) and polytetrafluoroethylene (PTFE) were co-sputter deposited on stainless steel micromolds to improve their surface properties. The sputtering power applied to the PTFE target was varied to control the PTFE concentration in the Ti–Al–PTFE coatings, which affected the bonding structure, surface roughness, friction and contact angle of coatings characterized using micro-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), confocal microscopy, ball-on-disc tribometer and goniometer, respectively. It was observed that the Ti–Al–PTFE coatings were a mixture of carbide, PTFE-like material and amorphous carbon. The surface roughness of coated micromolds decreased with the increase in the PTFE concentration. The Ti–Al–PTFE coating deposited with 50W sputtering power on the PTFE target showed the lowest friction coefficient and surface energy of about 0.17 and 13.1×10−3N/m, respectively. The coated stainless steel micromolds showed a better replication performance compared to the bare stainless steel micromolds in terms of the quality of polymeric microfluidic devices fabricated using hot embossing process. This work also investigated the coating properties at the sidewalls of the micromold channels and the limitations of the Ti–Al–PTFE coatings for application in hot-embossing.

Structure and Properties of Regenerated Cellulose Film with Fluorocarbon Coating

Abstract Fluorocarbon coatings were deposited on the surface of regenerated cellulose films by RF magnetron sputtering, using polytetrafluoroethylene targets. Argon was used as the working gas. The coatings were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, atomic force microscopy, static contact angle and oxygen permeability measurements. It was found that the coatings were made up of the four components -CF3, -CF2-, -CF- and -C-. The [F]/[C] ratio varied with sputtering conditions. The surface of fluorocarbon coatings had an undulate island structure. The static contact angle of the coatings was greater than 90° at lower power and higher pressure, and the substrate material was transformed from hydrophilic to hydrophobic character. The fluorocarbon coatings were porous and did not influence the oxygen permeability of the cellulose film substrates.

Preparation of polytetrafluoroethylene by pulsed electron ablation: Deposition and wettability aspects

Polytetrafluoroethylene (PTFE) has been prepared by pulsed electron deposition technique on glass and silicon substrates. Deposition of the thin films has been carried out in the temperature range from room temperature to 300 °C, pressure range from 133.32 × 10 −3 Pa to 799.93 × 10 −3 Pa, and discharge voltages between 10 kV and 16 kV. Argon or nitrogen has been used as a background gas during the deposition of the films. Attenuated Total Reflection Fourier Transform Infrared spectroscopy shows absorption peaks in the films at 644 cm −1, 1154 cm −1 and 1210 cm −1 consistent with those of PTFE target material. Atomic force microscopy and spectroscopic reflectometry reveal the clustered nature of the films and other morphological characteristics. Surface wettability of the films, expressed via the contact angle, has been measured via static angle goniometry. PTFE films increase the contact angle from about 32° (bare glass) and 43° (bare silicon) to up to 90° and 110° for PTFE-coated glass and silicon substrates, respectively. The contact angle decreases with an increase in both pressure and temperature, while it increases then decreases as the discharge voltage increases.

Optical property of fluorocarbon thin films deposited onto polyester film substrate by an r.f. sputtering

Fluorocarbon thin films prepared by an r.f. sputtering with a polytetrafluoroethylene (PTFE) target were deposited onto a transparent polyester film (polyethylene terephthalate: PET) substrate. Visible light transmittance of the PET film substrate improves due to the fluorocarbon coatings. Surface morphologies and chemical structures of these fluorocarbon thin films are considered to affect improvement of the transparency. However, we cannot explain why these thin films become transparent only with these two factors. Structure of the fluorocarbon thin film is suggested to be amorphous and we believe that this is one of the reasons why the fluorocarbon thin films sputtered with the PTFE target become transparent.

Structure and Properties of Regenerated Cellulose Film with Fluorocarbon Coating

Fluorocarbon coatings were deposited on the surface of regenerated cellulose films by RF magnetron sputtering, using polytetrafluoroethylene targets. Argon was used as the working gas. The coatings were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, atomic force microscopy, and static contact angle and oxygen permeability measurements. It was found that the coatings were made up of the four components -CF3, -CF2-, -CF- and -C-. The [F]/[C] ratio varied with sputtering conditions. The static contact angle of the coatings was greater than 90° at lower power and higher pressure, and the substrate material was transformed from hydrophilic to hydrophobic character. The fluorocarbon coatings were porous and did not influence the oxygen permeability of the cellulose film substrates.

Deposition of nanostructured fluorocarbon plasma polymer films by RF magnetron sputtering of polytetrafluoroethylene

The RF magnetron sputtering of polytetrafluoroethylene target is studied with the aim to find out conditions leading to the deposition of super-hydrophobic thin films. It is shown that such coatings can be prepared at elevated pressures and a longer distance between the sputtered target and the substrate. This is explained by an increase in the density of longer C xF y molecules that reach the substrate and a lower flux of ions and CF 2 radicals on the surface of growing film under such deposition conditions, as observed by optical emission spectroscopy and mass spectrometry. Such changes in plasma composition result in a deposition of rough films having F/ C ratio close to 2 as observed by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. These findings clearly distinguish our results from the previous investigations of polytetrafluoroethylene sputtering performed at shorter distances from the target, where either low F/ C ratio or low roughness of the deposited films did not allow reaching super-hydrophobic character of the coatings.

Secondary ion counting for surface-sensitive chemical analysis of organic compounds using time-of-flight secondary ion mass spectroscopy with cluster ion impact ionization

We report suitable secondary ion (SI) counting for surface-sensitive chemical analysis of organic compounds using time-of-flight (TOF) SI mass spectroscopy, based on considerably higher emission yields of SIs induced by cluster ion impact ionization. A SI counting system for a TOF SI mass spectrometer was developed using a fast digital storage oscilloscope, which allows us to perform various types of analysis as all the signal pulses constituting TOF SI mass spectra can be recorded digitally in the system. Effects of the SI counting strategy on SI mass spectra were investigated for C(8) and C(60) cluster ion impacts on an organically contaminated silicon wafer and on polytetrafluoroethylene targets by comparing TOF SI mass spectra obtained from the same recorded signals with different SI counting procedures. Our results show that the use of a counting system, which can cope with high SI yields, is necessary for quantitative analysis of SI mass spectra obtained under high SI yield per impact conditions, including the case of cluster ion impacts on organic compounds.

Investigation of laser ablation loading of polymers

For polyethylene and polytetrafluoroethylene targets irradiated by laser pulses with energy densities within 100–1000 J/cm2, the ablation loading coefficients amount to 8–11% and 8–10%, respectively. These values satisfactorily agree with theoretical estimates of the ablation loading, which are about 6–8%.

Characterization of organic polymer thin films deposited by rf magnetron sputtering

Organic polymer thin films deposited by sputtering using polytetrafluoroethylene (PTFE) and polyimide (PI) targets were investigated with Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscopy (SEM). Films deposited from the PTFE target were poly-hydro-fluoro-carbon. The thin films showed water repellency with an H 2O contact angle of about 110° and were transparent in the visible region. C–F combination states in the films were similar to those of bulk PTFE. Films deposited from the PI target were found to contain C–N bonds and were harder than bulk PI. The color of thin films was dark brown, showing the existence of C–N bonds, such as those in imide and/or amide groups. However, the combination states characterized by FTIR and XPS analyses were considerably different from those of bulk PI. The difference in chemical composition and combination states between the films deposited from PTFE and PI is thought to result from the difference in types of particles sputtered from the targets; in the case of PTFE sputtering, less C–F bonds are broken by collision of Ar ions for sputtering, whereas in the case of PI sputtering, C–H and C–C bonds are broken by collision of Ar ions.

Generation of over 5MeV carbon ions from a fibrous polytetrafluoroethylene film irradiated with a 2.4TW, 50fs tabletop laser

The authors generated energetic carbon ions C4+ above 5MeV by focusing 2.4TW, 50fs, 10Hz laser pulses onto a fibrous polytetrafluoroethylene (PTFE) film. The PTFE film is composed only of carbon and fluorine and has microporous structure. A laser target made of this film is useful in generating carbon ions. A polyethyleneterephthalate film was also used as an alternative target for comparison. The results show that the number of carbon ions emitted from the PTFE target was approximately two orders of magnitude greater than that from a polyethyleneterephthalate target.

Polytetrafluoroethylene (PTFE) films prepared by F2-laser deposition

Thin films of polytetrafluoroethylene (PTFE) were prepared by pulsed-laser deposition (PLD) from bulk PTFE targets using 157 nm F 2 -laser radiation. The films were analyzed by means of optical polarization microscopy, stylus profilometry, XPS, XRD, FTIR spectroscopy, and by capacitance measurements. The effect of substrate temperature, T s , on the morphology and crystallinity of the films was studied. Films treated at sufficiently high T s consist mainly of spherulite-like crystallites. Films with a thickness of more than about 155 nm are continuous, pinhole-free, well adherent to the substrate, and have a composition which is similar to that of the target material. The minimum film thicknesses and deposition rates are much lower than those achieved with pressed PTFE powder targets using 248 nm KrF-laser ablation. This is related to the different deposition mechanisms. Film formation based on KrF-laser ablation of pressed powder targets is mainly related to the condensation of large particulates transferred in a particle jet from the target to the substrate. F 2 –laser ablation and film formation seems to be based on the ablation and condensation of small fragments. Correspondingly, the morphology, crystallinity, and the optical and dielectrical properties of films significantly differ from each other.

Fluorine-Doped SiO2 Films Made from Silicone and Polytetrafluoroethylene Using an F2 Laser

In the present paper, we propose a novel method which permits us to fabricate fluorine-doped silicon dioxide (F-doped SiO2) films on various substrates at room temperature. The films were selectively grown on a substrate by simultaneous 157-nm F2 laser illumination of a silicone rubber target, a polytetrafluoroethylene (PTFE) target, and the substrate. Fourier transform infrared spectroscopy (FT-IR) spectra and X-ray photoelectron spectroscopy (XPS) spectra showed that the films had a uniform fluorine concentration in the depth direction and no contaminants, such as carbon and hydrocarbon. The films were photochemically grown on the substrate in an atmosphere of gases evolved from silicone and PTFE by F2 laser illumination. The relative dielectric constant of the films was lower than that of the SiO2 films grown by F2 laser illumination without a PTFE target, namely, 3.6 at a laser fluence of 22 mJ/cm2. The F-doped SiO2 film formed at a higher a laser fluence had a lower refractive index and lower relative dielectric constant.