Plasma-polymerized Organosilicon Research Articles

Structure and chemical composition of thin-film nanocomposites based on silver in organosilicon amorphous matrix prepared by High Target Utilization Sputtering

Thin films based on Ag nanoclusters embedded in an organosilicon polymer matrix were deposited using the High Target Utilization Sputtering technique (HiTUS) by simultaneous sputtering of the Ag target and polymerization of hexamethyldisiloxane (HMDSO) vapors in radiofrequency plasma. The influence of deposition parameters on chemical composition and structure of the deposited nanocomposite films was studied using scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray diffraction analytical techniques. The films under investigation exhibit a dense uniform structure with the metallic nanocrystalline silver present in the form of spherical-shaped nanoclusters with dimensions below 10 nm embedded in an amorphous organosilicon plasma polymer. The average size of Ag nanoclusters is increased from 1.8 to 4.4 nm with Ag content increasing from 16 to 57%at. while concentration of nanoclusters is reduced. Incorporation of the metallic silver into the plasma polymerized HMDSO leads to a decrease of carbon and oxygen content as well as a decrease of organosilicon polymer matrix density.

Comparative study of bulk and surface compositions of plasma polymerized organosilicon thin films

Plasma polymerized organosilicon thin films were deposited in a MW-PECVD using hexadimethylsiloxane (HMDSO) as a precursor. Thin films were synthetized with different plasma conditions ranging from soft (low plasma energy) to hard (high plasma energy) ones. Quantitative 29Si solid state NMR and FTIR spectroscopy were used to characterize the bulk composition. X-ray photoelectron spectroscopy (XPS) coupled with Density Functional Theory (DFT) calculations were used to determine the surface chemical composition. In addition, water contact angle (WCA) measurements were performed in order to complete the surface characterization. The bulk and the surface of the plasma polymerized HMDSO (PP-HMDSO) showed a complex chemical composition. The four main environments M, D, T and Q were present in the films. An additional environment Si(CH2)(CH3)3 denoted S was detected in the PP-HMDSO films. The chemical composition comparison showed a difference between the bulk and the surface of the films. Under soft plasma conditions, a high amount of SiOC3 termination was present in the bulk of the films. While, the SiO2C2 chains were highly present on the surface. On the other hand, under hard plasma conditions, the number of the SiOC3 termination increased on the surface and decreased in the bulk. Under soft plasma conditions, the PP-HMDSO structure was close to PDMS, while under hard plasma conditions, the PDMS similarity was lost.

Plasma CVD/etching of Poly(methyl methacrylate) surface: optical and structural characterizations

Poly (methyl methacrylate) (PMMA) optical polymer surface has been treated in a RF remote plasma system, in three different plasma environments. Firstly, its surface has been coated with a plasma polymerized organosilicon precursor (Hexamethyldisilazane: HMDSN), secondly, PMMA surface has been exposed to oxygen plasma, and thirdly SF6 plasma has been used to treatment PMMA surface. The impact of plasma treatment on PMMA surface properties has been monitored using different characterizations techniques: optical reflectance, wettability by using water contact angle measurement, surface morphology using atomic force microscopy (AFM) and chemical structure using attenuated total reflectance of Fourier transformer infrared spectroscopy (ATR-FTIR). The correlations between the different properties have been discussed. The results revealed the possibility of tuning the optical and wetting PMMA surface properties by plasma surface treatment, according to the induced changes in surface morphology and chemical structure after plasma treatment. Particular interesting results are lowest reflectance after PMMA surface O2 plasma exposure and high hydrophobic surface obtained after SF6 plasma surface treatment.

Cold atmospheric pressure plasma-polymerized organosilicon oxide films for enhancing scratch resistance of flexible carbon fiber-reinforced polymer composites

A noteworthy enhancement on the scratch resistance of flexible carbon fiber-reinforced polymer composites (FCFRPCs), by a rapid deposition (a short exposure duration of 150 s) of organosilicon oxide (SiOxCy) films, with an atmospheric pressure plasma jet (APPJ), via the addition of air gases at various flow rates, has been investigated. The precursor tetramethyldisiloxane vapors are mingled with air gases, injected into an air plasma jet and sprayed onto FCFRPCs using an APPJ at room temperature (~23 °C) and atmospheric pressure for the synthesis of SiOxCy thin films onto FCFRPCs to improve the scratch resistance. A scratch test with steel wool at a 100 g load, demonstrates that the scratch resistance of FCFRPCs is obviously increased from an overwhelming presence of scratching (100%) on as-received FCFRPC to a complete lack of scratching (0%) on the SiOxCy film deposited FCFRPC for up to 92 cycles. The surface characteristics, such as surface hardness, surface morphology, surface compositions and chemical bonds of atmospheric pressure plasma-polymerized SiOxCy films, are examined to find how to progress in the scratch resistance of FCFRPCs with an APPJ by air gas addition.

Characterization of plasma polymerized organosilicon thin films deposited on 316L stainless steel

This study focused on the characterization of the organosilicon films deposited on 316L stainless steel (316L SS) substrate using a plasma polymerization process with hexamethyldisiloxane (HMDSO) precursor and different N2 gas flow rates. The organosilicon film had a C-rich composition as deposited using only HMDSO precursor. The nitrogen content of thin film consecutively increased with increasing N2 flow rate up to 15 sccm. The film deposition rate increased with increasing N2 flow rate. All films exhibited the smooth and pinhole free surfaces. Good adhesion property was obtained for each film after scratch test. Better biocompatibility and cell adhesion was observed for the nitrogen free organosilicon film as compared with that of the untreated 316L SS. Further enhancement of biocompatibility was found for those films with N2 addition. The best biocompatibility, highest transmittance, less hydrophobic surface, and excellent wear resistance were noted for the film grown under 5 sccm N2 flow rate. Such film performance makes it become a promising candidate as the surface coating layer on 316L SS for biomedical application.

Single-step generation of metal-plasma polymer multicore@shell nanoparticles from the gas phase

Nanoparticles composed of multiple silver cores and a plasma polymer shell (multicore@shell) were prepared in a single step with a gas aggregation cluster source operating with Ar/hexamethyldisiloxane mixtures and optionally oxygen. The size distribution of the metal inclusions as well as the chemical composition and the thickness of the shells were found to be controlled by the composition of the working gas mixture. Shell matrices ranging from organosilicon plasma polymer to nearly stoichiometric SiO2 were obtained. The method allows facile fabrication of multicore@shell nanoparticles with tailored functional properties, as demonstrated here with the optical response.

Organosilicon Coatings Deposited in Atmospheric Pressure Townsend Discharge for Gas Barrier Purpose: Effect of Substrate Temperature on Structure and Properties

Organosilicon plasma polymer and silicalike layers are deposited at different temperatures in a dielectric barrier discharge at atmospheric pressure operating in the Townsend regime. Final properties of these two kinds of layers can be finely tuned by the plasma process conditions. In particular, influence of deposition temperature is investigated when hexamethyldisiloxane based monolayers are deposited on poly(ethylene naphtalate) substrate. Coating chemical structure is tested by means of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Their thickness, topography, and mechanical properties are evaluated by ellipsometry, scanning electron microscopy observation of coatings cross sections, atomic force microscopy, and nanoscratch testing. Permeability of coated polymer is measured for transparent silicalike layers, and the effect of coating structure on the oxygen gas permeability is discussed. The deposition temperature of coatings at 90 °C provides a strong improvement in barrier property compared to room temperature deposition, thanks to a densification of the SiO₂ matrix and to a decrease in the silanol group content.

Enhanced scratch resistance of flexible carbon fiber-reinforced polymer composites by low temperature plasma-polymerized organosilicon oxynitride: The effects of nitrogen addition

An investigation is conducted on enhanced scratch resistance of flexible carbon fiber-reinforced polymer composites (FCFRPCs) by low temperature plasma-polymerized organo-silicon oxynitride (SiO x C y N z ) at varying N 2 concentrations. It is found that the organic–inorganic hybrid films (SiO x C y N z ) deposited on FCFRPCs using tetramethylsilane (TMS) O 2 N 2 plasmas at low temperature dramatically improve the scratch resistance of FCFRPCs. Scratch resistance is greatly enhanced from an overwhelming presence of scratching (100%) on untreated FCFRPCs to a complete lack of scratching (0%) on TMS O 2 N 2 plasma-polymerized FCFRPCs with steel wool for 250 cycles at 200 g loading. The scratch resistance of FCFRPCs is found to be highly dependent on their surface characteristics including hardness, surface morphology, surface compositions and chemical bonds of TMS O 2 N 2 plasma-polymerized SiO x C y N z .

Enhanced surface hardness of flexible polycarbonate substrates using plasma-polymerized organosilicon oxynitride films by air plasma jet under atmospheric pressure

An investigation is conducted on the enhanced surface hardness of flexible polycarbonate (PC) substrates using high-rate deposition (~19.1–19.9nm/s) of plasma-polymerized organosilicon oxynitride (SiOxCyNz) films with an atmospheric pressure plasma jet (APPJ) at various substrate distances. It is found that the transparent, hard and flexible SiOxCyNz films can be deposited onto PC substrates at room temperature (23°C) by injection of precursor tetramethyldisiloxan (TMDSO) into air plasma jet at atmospheric pressure. Pencil hardness measurements (ASTM d-3363) demonstrate that the surface hardness of the PC substrate is greatly enhanced from a soft surface of 3B for un-coated PC substrate to a hard surface of 7H for SiOxCyNz film-coated PC substrate. This study indicates that the performance of surface hardness on PC substrates is highly dependent on the surface characteristics of the PC substrates. The surface morphology of the PC substrate is observed by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). The atomic compositions and chemical bonds of APPJ-synthesized SiOxCyNz films are analyzed using X-ray photoelectron spectroscopy (XPS) and Fourier transformed infrared spectroscopy (FTIR).

Insights in Molecular Structure of Organosilicon Plasma Polymer Produced by Means of Atmospheric Pressure Dielectric Barrier Discharge Process

AbstractMost of polymers resulting from plasma polymerization exhibit a structure, which is very complex and different from those synthesized by conventional polymerization methods. The molecular structure of such plasma polymers is difficult to assess, but its characterization is a crucial issue. Mass spectrometry (MS) seems to be a promising analytical approach to get this molecular information. The chemical structure of a ppHMDSO (plasma polymer HexaMethylDiSiloxane) film, deposited by means of atmospheric pressure dielectric barrier discharge process, has first been characterized by means of FTIR spectroscopy. Additional insights in the polymer structure were provided by mass spectrometric techniques. MALDI‐TOF‐MS and ESI‐Q‐TOF‐MS analyses were carried out to obtain information on high molecular weight oligomers and/or small polymers collected in the THF soluble fraction of a ppHMDSO film. Although uncertainty still remains about the detected species, it could be concluded they were copolymers such as poly(dimethylsiloxane‐co‐methylsiloxane) or poly(dimethylsiloxane‐co‐SiO2) with a number of monomers up to 20, and some structures could be proposed for the end groups.magnified image

Synthesis of Organosilicon Film on Polycarbonate by Means of Low-Temperature Atmospheric-Pressure Plasma Jet

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Plasma-polymerized organosilicon films are deposited at room temperature by a novel double-pipe-type atmospheric-pressure plasma jet (APPJ), using hexamethyldisilazane (HMDSN) as precursor and argon (Ar) as carrier gas. The surface properties of the resulted plasma films are investigated as a function of radio-frequency plasma power and position from the plasma nozzle. The atmospheric-pressure plasma-polymerized films have been analyzed by static contact angle measurement, a Fourier transform infrared spectrometer, a UV–vis spectrometer, and atomic force microscopy. The ultrathin APPJ-polymerized films have been studied and correlated to chemical composition and surface morphology. UV–vis spectra have demonstrated the optical transparency of the APPJ polymerized films. </para>

Use of a PECVD–PVD process for the deposition of copper containing organosilicon thin films on steel

A low frequency plasma process is used to deposit thin films on steel through simultaneous sputtering and plasma enhanced chemical vapour deposition (PECVD). The deposited material consists in composite copper–organosilicon thin layers where copper is obtained by magnetron sputtering whereas the organosilicon plasma polymer is grown by PECVD from HMDSO (hexamethyldisiloxane). This paper focuses on the important process parameters required to control the quantity of incorporated copper in the layer, particularly the metalorganic concentration and the sputtering current. The dispersion of copper vs. the thin film thickness is found to be homogeneous. The deposited layers show antimicrobial activity for copper contents higher than X = 38%, where X = [Cu]/([Cu] + [Si]).

Optical and photoluminescent properties of plasma polymer films used in electroluminescent display structures

The optical and photoluminescent properties of plasma polymer layers synthesized from hexamethyldisiloxane are examined. The value of the polymer layer transparence is in the limits from 55% at 400 nm to 88% at 800 nm. Photoluminescence is stimulated by using the spectral line λ=365 nm emitted by a Hg spectral lamp. The organosilicon plasma polymers are included as protective and capsulating layers in electroluminescent (EL) structures. The structure obtained is characterized by a significant increase in emission brightness, compared to inorganic protective layers. For EL structures with a chalcogenide protective layer the increase is more than 6 times and for structures with heterogeneous matrix on the base of TiO 2 it is more than 20 times. As a stable covering the organosilicon plasma polymer increases the lifetime of the EL structures too.

Study on organosilicon plasma polymers implanted by carbon ions

In the present work plasma polymer films obtained from hexamethyldisiloxane have been implanted by carbon ions at three different doses. The photoluminescent properties of the implanted polymers were investigated. The optical transmission of these polymer layers was investigated in the visible spectral region. Their electrical parameters were also measured. It was found that the resulting changes do not worsen the protective properties of the implanted polymer layer. The variations in the properties studied might be ascribed to the nanostructured carbon clusters formed on the polymer surface. The results obtained could form the basis for further optimization of the polymer structure by carbon ion implantation in view of applications in electroluminescent display structures.

Corrosion protection of a thin aluminium layer deposited on polyester

Organosilicon plasma polymer layers were deposited by surface dielectric barrier discharge (DBD) at atmospheric pressure, in an attempt to enhance the corrosion protection of a reflective aluminium (Al) layer applied on a polyester (PET) fabric. A number of tests were carried out to characterize the improvement of corrosion resistance – namely sodium carbonate (Na 2CO 3), water vapor and Kesternich tests – as a function of plasma treatment time, type of carrier gas, admixture of oxygen, amount of hexamethyldisiloxane (HMDSO) precursor supplied to plasma and post-plasma-treatment heating. Moreover, plasma-deposited protective films were characterized by the scanning electron microscopy (SEM), infrared spectroscopy (DRIFT FTIR), and X-ray photoelectron spectroscopy (XPS). While aluminium was consumed in the Na 2CO 3 corrosive solution within a few minutes for the untreated surface, the optimally performing plasma polymerized layers revealed an extraordinary corrosion resistance. Furthermore, the best protective organosilicon coatings showed only a 1–2% absolute reduction of reflection compared to the untreated fabric, over the complete solar spectrum (250–2500 nm).

Deposition of protective coatings in rf organosilicon discharges

The paper discusses the deposition of protective coatings ranging from organosilicon plasma polymers to SiO2-like films and hard diamond-like carbon/silicon oxide (DLC : SiOx) coatings in radio frequency capacitively coupled discharges using hexamethyldisiloxane (HMDSO). As a result of the optimization of the deposition conditions it was possible to obtain high performance protective coatings. In the HMDSO/O2 mixture, it was shown that rather than the SiO2-like film a hard cross-linked SiOxCyHz polymer film can be used as a protective coating for polycarbonate. The optimum conditions for the deposition of an almost stress-free film were 17% of HMDSO and dc bias voltage of −240 V. The film hardness and elastic modulus were 10 GPa and 75 GPa, respectively. The refractive index at 600 nm was 1.5 and the extinction coefficient decreased from 0.02 at 240 nm down to zero at 600 nm.The films deposited from HMDSO/CH4 and HMDSO/CH4/H2 mixtures exhibited the attractive properties of DLC films with the partial elimination of some of their drawbacks, such as absorption in the visible and a high intrinsic stress. The optimum concentration of the HMDSO was approximately 21%. Under these conditions the concentration of SiOx in the films was approximately 9 at.%. The film hardness and elastic modulus were above 22 GPa and 120 GPa, respectively.

Front Cover: Plasma Process. Polym. 4‐5/2006

Front Cover: Organosilicon plasma polymer thin films undergo modifications as they are exposed to an oxygen plasma. Under well chosen oxygen plasma conditions, they can even be converted into SiO2‐like films as shown by FTIR transmission spectra and X‐ray reflectometry measurements. Further details can be found in the Full Paper by A. Granier*, G. Borvon, A. Bousquet, A. Goullet, C. Leteinturier, and A. van der Lee on page 365.

Surface-enhanced Raman spectroscopy of the growth of ultra-thin organosilicon plasma polymers on nanoporous Ag/SiO2-bilayer films

A new method for the synthesis of thin bilayer films as surface-enhanced Raman spectroscopy (SERS) active substrates was developed which is based on the combination of plasma polymerization, plasma calcination and Ag-film deposition by means of physical vapor deposition. The surface morphology of prepared substrates was characterized by field emission scanning electron microscopy, atomic force microscopy and electrochemical impedance spectroscopy. These substrates lead to high surface enhancement factors proven by the spectroscopic analysis of adsorbed Trans-1,2 bis-(4-pyridyl) ethylene molecules. By this preparation technique, SERS-active films can be deposited on any substrate. The new SERS substrates were successfully applied to study the growth of ultra-thin hexamethyldisiloxane plasma polymer films. The Raman intensity of the CH-stretching vibration was studied as a function of the film thickness. The surface enhancement decreased sharply at about 20 nm. The resulting increase in the intensity of Raman peaks for thin adsorbed plasma polymer films was observed to be a combination of the electromagnetic enhancement mechanism and the high surface area increase of the rough Ag-surface.

RF-power-controlled young's modulus of plasma-polymerized organosilicon films

RF-power-controlled young's modulus of plasma-polymerized organosilicon films

Tunable waveguides via photo-oxidation of plasma-polymerized organosilicon films

Plasma-enhanced chemical vapor deposition (PECVD) of dimethylsilane and hexamethyldisilane produced thin films with a refractive index of 1.56 +/- 0.01 at 633 nm. A decrease in the refractive index of approximately 3% was observed after irradiation with UV light from an ArF laser operating at 193 nm. Lower-intensity UV light from a Hg arc lamp induced a slower and controllable decrease in the refractive index. Top-side prism coupling showed the as-deposited organosilicon films to be multimode at 633 nm and single mode at 1550 nm. A model predicted that 30 s of UV irradiation with the Hg arc lamp would decrease the refractive index of the light-guiding film by approximately 0.01, converting the waveguide into single-mode operation across the spectrum of essential wavelengths for microphotonics. Irradiation followed by further coupling experiments confirmed this tunability. Trimming the refractive index of patternable organosilicon polymeric films presents a method of optimizing the coupling performance of PECVD microphotonic interconnect layers postdeposition.