Atmospheric pressure plasma jet was used to deposit polymer films from argon/air/acetylene mixture. Depending on the gas composition, three modes of operation were observed and characterized. The film deposited by a stationary jet had a circular shape with area (where thickness was almost constant) about the nozzle inner diameter. The deposition rate of stationary jet decreased with the time: a film of 2 μm was obtained after the first two minutes, while in the next two minutes only 1.3 μm film was deposited. The plasma polymers were characterized by infrared spectroscopy, where variety of C\ \H and few C\ \O bonds were detected. By using a linear displacement system, we obtained homogeneous deposition over a larger area with deposition rate of about 330 nm/ min, showing the potential of such plasma jet system for large-scale depositions.

Deposition of plasma polymers using atmospheric pressure plasma jet in mixture of argon, air and hexamethyldisilazane (HMDSN) was studied. The HMDSN monomer, used as film precursor, was carried to the jet nozzle by an auxiliary airflow and mixed with principal argon flow. The films were deposited for different times using mean discharge power of 2.8 W, main argon flow of 1 SLM while the carrier flow (air + HMDSN) was 0.1 SLM. The water contact angles measured across the obtained HMDSN plasma polymer film showed two welldefined areas, one hydrophilic, with contact angle near zero degrees and one hydrophobic, with contact angle around 100 degrees. The FTIR spectra showed that part of the original structure of HMDSN monomer was preserved and new chemical bonds were observed. XPS analysis showed that the deposited coatings are inorganic SiO 2-like coatings. The films thickness was evaluated and it reached values about 2 μm in the center and decreased to the border (in continuous deposition mode more rapidly than in the pulsed one). Roughness values were obtained and it is shown that they varied for each region of the film.

Abstract. In this work, it was used a plasma system composed of a cylindrical stainless steel reactor, a radio-frequency (13.56MHz) power source fixed at either 25 W or 70 W, a power source with a negative bias of 10kV and a 100Hz pulse. The system worked at an operational pressure of 80mTorr which consisted of varying concentrations of the monomer HMDSN and gaseous nitrogen in ratios: HMDSN (mTorr)/nitrogen (mTorr) from 70/10 to 20/60 in terms of operational pressure. The structural characterization of the films was done by FTIR spectroscopy. Absorptions were observed between 3500 cm -¹ to 3200 cm -¹, 3000 cm -¹ to 2900 cm -¹, 2500 cm -¹ to 2000 cm -¹, 1500 cm -¹ to 700 cm -¹, corresponding, respectively, to OH radicals, C-H stretching bonds in CH2 and CH3 molecules, C-N bonds, and finally, strain C-H bonds , Si-CH3 and Si-N groups, for both the 70 W and the 25 W.The contact angle for water was approximately 100° and the surface energy is near 25mJ/m² which represents a hydrophobic surface, measured by goniometric method. The aging of the film was also analyzed by measuring the contact angle over a period of time. The stabilization was observed after 4 weeks. The refractive index of these materials presents values from 1.73 to 1.65 measured by ultraviolet-visible technique.

Plasma polymer thin films are pinhole-free and have also a high cross-linked structure. These kinds of films are insoluble in mild acids and bases and present good adhesion on different materials. These features make the films relevant for industrial applications and are used in different fields such as electronics, mechanics, biomedics, electrics, protective coatings and others. The plasma polymer hexamethyldisilazane/argon films (ppHMDSN/Ar) were deposited on substrates which were placed between two stainless steel parallel plate electrodes fed by a radio-frequency source operated at 13.56 MHz and 50 W at a total pressure (HMDSN and argon) of 80 mTorr. The negative bias of 10 kV and 10 Hz pulse were used for ion implantation. The structural characterization of the films was done by FTIR spectroscopy. The contact angle for water was of approximately 98°and the surface energy of 30 mJ/m 2 which represents a hydrophobic surface, measured by goniometric method. The refractive index of these materials presents values from 1.56 to 1.64 measured by ultraviolet-visible technique. The thickness of the samples was measured by profilometry and showed values from 96 to 210 nm for different deposition conditions resulting in deposition rates from 4.8 to 10.5 nm/min. Hardness values ranging from 0.9 to 2.6 GPa were found for the films measured by nanoindentation technique.

A conical-shaped atmospheric pressure plasma jet (CS-APPJ) was developed to overcome a standard limitation of APPJs, which is their small treatment area. The CS-APPJs increase the treatment area but use the same gas flow. In the present work, polypropylene samples were treated by CS-APPJ and characterized by scanning electron microscope (SEM), the contact angle, Fourier-transformed infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). It was observed that the treatment co-occurs on the face directly in contact with the plasma and on the opposite face (OF) of the samples, i.e., no contact. However, the treatment changed the chemical composition on each side; the OF is rougher than the direct contact face (DCF), probably due to the oxygen groups in excess at the DCF and nitrogen in quantity at the OF. Although simultaneous treatment of both sides of the sample occurs for most atmospheric plasma treatments, this phenomenon is not explored in the literature.