Multi-walled carbon nanotubes (MWCNT) were coated by polyaniline (PANI) in situ during the oxidation of aniline with ammonium peroxydisulfate in a mixture of ethanol (50 vol.%)–water. PANI alone and ...PANI-coated MWCNT were carbonized under nitrogen atmosphere at 650 °C and the structural changes were studied by infrared spectroscopy and Raman scattering using 633 and 785 nm excitation lines. MWCNT coated with carbonized PANI salt exhibit a Raman spectrum close to that of the pristine MWCNT before heating. In contrast, the spectra of MWCNT and MWCNT coated with PANI base correspond after exposure to 650 °C to a more disordered carbon-like material according to their Raman spectrum. This means that the coating with PANI salt has a protective effect on the structure of MWCNT when exposed to elevated temperature. During heating, the overlayer of PANI salt thermally deprotonates to PANI base at first, and subsequently converts to a carbonized PANI coating. The integrity of the coating is not damaged. When the PANI coating was chemically deprotonated to PANI base before heating, the accompanying volume contraction reduced the contact between MWCNT and PANI base coating and introduced defects, such as cracks. The protective effect of PANI coating was then lost. The possible interactions between PANI and MWCNT are discussed on the basis of Raman spectra.
Fluorocarbon plasma polymer films were prepared by RF magnetron sputtering in Argon from a balanced magnetron equipped with polytetrafluoroethylene (PTFE) target. Depending on the deposition ...conditions, primarily on the working gas pressure and distance between the target and the substrate, plasma polymer films were obtained with distinctly different chemical composition and/or morphology, as measured by means of XPS, FTIR and AFM. These films possessed static contact angle of water values ranging from 112° to ≈170° i.e. their behaviour ranged from hydrophobic to superhydrophobic ones.
Fluorocarbon plasma polymer coatings having a super‐hydrophobic character are prepared by means of magnetron sputtering of polytetrafluoroethylene target in an argon atmosphere. It is demonstrated that Ar pressure and substrate target distance are the key parameters determining wettability of the coatings, since they influence significantly morphology and chemical composition of the deposited films.
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.
In this study we report on the deposition of Pt nanocluster films prepared by gas aggregation source that was operated with argon as working gas. The aim of this study was optimization of deposition ...process as well as determination of properties of deposited nanocluster films and their temporal stability. It was found that the production of Pt nanoclusters reached maximum value for pressure of 100Pa and increases monotonously with magnetron current. The deposition rate at optimized deposition conditions was 0.7nm of the Pt nanocluster film per second. Deposited films were porous and composed of 4nm Pt nanoclusters. The nanoclusters were metallic and no sights of their oxidation were observed after 1year on open air as witnessed by X-ray photoelectron spectroscopy. Regarding the electrical properties, a dramatic decrease of the resistivity was observed with increasing amount of deposited nanoclusters. This decrease saturated for the films approximately 50nm thick. Such behavior indicates transition between different mechanisms of electrical conductivity: charge hopping for thin discontinuous films and current conduction through conducting path formed when higher amount of nanoclusters is deposited. Different mechanisms of electrical conduction for thin and thick layers of Pt were confirmed by subsequent investigation of temperature dependence of resistivity. In addition, no changes in resistivity were observed after one year on open air that confirms stability of produced Pt nanocluster films.
•Pt nanocluster films were deposited by gas aggregation nanocluster source.•Conditions leading to effective deposition of Pt nanocluster films were found.•Deposited nanocluster films have good temporal stability.•Electrical properties of Pt films were found to depend on their thickness.
The study describes the preparation and properties of Al/Al
x
O
y
nanoparticles and their nanocomposites with hydrocarbon plasma polymer. The nanoparticles were deposited using a simple gas ...aggregation cluster source based on a planar magnetron. The influence of deposition parameters on size distribution was studied. It was found that Al nanoparticles may be deposited with mean diameter ranging from 30 to 60 nm by varying magnetron current from 0.4 to 0.2 A. Attention was also paid to the investigation of the charge of the nanoparticles. It is shown that a large portion of Al
x
O
y
nanoparticles leave the gas aggregation source as negatively charged. The nanoparticles were also embedded into the plasma polymer matrix by their simultaneous co-deposition with plasma-polymerized
n
-hexane. Morphology and chemical composition of such fabricated nanocomposites were determined. It was shown that Al
x
O
y
nanoparticles embedded into the polymeric matrix exhibit localized surface plasmon resonances in the deep ultraviolet region of the electromagnetic spectrum and the position of the plasmon peak is strongly correlated with nanoparticle size.
In this thesis the optical properties of the plasma polymers are studied using the spectroscopic ellipsometry. The basic principles of ellipsometry are described. The suitability of various ...ellipsometric models for the modelling of plasma polymer thin filmsis compared. The stability of films prepared by sputtering of nylon is studied. The influence of the deposition conditions on the optical properties of hydrocarbon plasma polymer film is characterized. Usability of the ellipsometric roughness for the characterization of the nanostructured hydrophobic surfaces is tested. The filling factor of metal/plasma polymer nanocomposites is determined and compared with another methods of filling factor determination.
The optical emission spectrum of acetylene excited by monoenergetic electrons was studied in the range of 190–660 nm. The dissociative excitation and dissociative ionization associated with ...excitation of the ions initiated by electron impact were dominant processes contributing to the spectrum. The spectrum was dominated by the atomic lines (hydrogen Balmer series, carbon) and molecular bands (CH(A–X), CH(B–X), CH+(B–A), and C2). Besides the discrete transitions, we have detected the continuum emission radiation of ethynyl radical C2H(A–X). For most important lines and bands of the spectrum we have measured absolute excitation-emission cross sections and determined the energy thresholds of the particular dissociative channels.
The optical emission spectrum of acetylene excited by monoenergetic electrons was studied in the range of 190-660 nm. The dissociative excitation and dissociative ionization associated with ...excitation of the ions initiated by electron impact were dominant processes contributing to the spectrum. The spectrum was dominated by the atomic lines (hydrogen Balmer series, carbon) and molecular bands (CH(A-X), CH(B-X), CH+(B-A), and C2). Besides the discrete transitions, we have detected the continuum emission radiation of ethynyl radical C2H(A-X). For most important lines and bands of the spectrum we have measured absolute excitation-emission cross sections and determined the energy thresholds of the particular dissociative channels.
The optical emission spectrum of acetylene excited by monoenergetic electrons was studied in the range of 190 nm to 660 nm. The dissociative excitation and dissociative ionization associated with ...excitation of the ions initiated by electron impact were dominant processes contributing to the spectrum. The spectrum was dominated by the atomic lines H, C and molecular bands of CH, CH, CH+, and C2. Besides the discrete transitions, we have detected the continuum emission radiation of ethynyl radical C2H. For most important lines and bands of the spectrum we have measured absolute excitation-emission cross sections and determined the energy thresholds of the particular dissociative channels.
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