Polyacrylic acid thin films have been deposited by an original and fast technique to grow organic coatings: a pulsed‐arc atmospheric pressure plasma jet. Liquid acrylic acid was introduced in the nitrogen plasma jet and OES was used to measure the fragmentation of the precursor. The films were characterized by XPS, FTIR and SEM analyses before and after soaking in water. The water stability was also investigated by weight loss measurement. A high retention of carboxylic moieties, i.e. functional groups of the monomer has been observed for coatings deposited under mild conditions for the jet (low frequency and high jet speed). These films have been used for cell adhesion using human ovarian carcinoma cells (NIH:OVCAR‐3). Good results have been obtained depending on the plasma parameters, showing that atmospheric pressure plasma jet is a promising technique to grow organic thin films for biomedical applications.magnified image

Plasma polymerized polyacrylic acid (PPAA) was deposited on a polymer substrate, namely polyethylene terephthalate (PET) mesh, for entrapment of silver nanoparticle (Ag-NP) in order to achieve antibacterial property to the material. Carboxylic groups of PPAA act as anchor as well as capping and stabilizing agents for Ag-NPs synthesized by chemical reduction method using NaBH(4) as a reducing agent. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), and water contact angle analysis were used to characterize the PPAA coatings. The Ag-NPs loaded polymer samples were characterized by UV-visible spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray, and XPS techniques. XPS analysis showed ~1.0 at.% loading of Ag-NPs on to the PPAA-PET-mesh, which was composed of 79% zero-valent (Ag°) and 21% oxidized nano-Ag (Ag(+) ). The plasma processed PET meshes samples were tested for antibacterial activity against two bacterial strains, namely Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative). Qualitative and quantitative tests showed that silver containing PPAA-PET meshes exhibit excellent antibacterial property against the tested bacteria with percent reduction of bacterial concentration >99%, compared to the untreated PET mesh.

Silicon oxide based (SiOxCyHz, noted SiOx) coatings are often used in surface engineering for microelectronics, corrosion resistance, barrier to gas permeation through polymeric materials, etc… SiOx coatings can be efficiently deposited by non‐equilibrium atmospheric pressure plasma processes, such as DBD or plasma jets. In the present study, the design of experiment (DoE) methodology was used to investigate the influence of process parameters on the characteristics of organosilicon coatings deposited by a non‐equilibrium atmospheric pressure plasma jet (APPJ) from hexamethyldisiloxane (HMDSO) and air mixtures. The results obtained were used to create an empirical model to predict the chemical composition of coatings. Among 11 process parameters, the 3 parameters which exhibited the strongest effect on the coating composition were the torch speed, the substrate to nozzle distance and the number of scans. Auger spectroscopy revealed that the carbon content of the thin films was as low as 6 ± 1.7% and AFM analysis showed that smooth coatings (Ra ∼ 2 nm) were obtained even at high dynamic growth rates (∼1 000 nm · m · min−1). A tentative macroscopic scaling law was also formulated to correlate our results with the available literature data.

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N-doped TiO 2 thin films have been prepared by reactive RF magnetron sputtering at different pressures and with different compositions using a dual reactive gas mixture of nitrogen and oxygen. The morphological, optical, photo-electrochemical and photocatalytic properties have been studied in order to investigate the white light and visible light photoactivities of the films. Significant control over the band gap energy in the films was achieved by varying the deposition parameters. Photoelectrochemical characterization revealed improved white light photocurrent generation in nitrogen doped films prepared at low pressures. However, the visible light photocurrent generation showed improvement for all deposition pressures, and changed accordingly with the nitrogen incorporation. Photocatalytic measurements of a common chemical pollutant NMP (N-Methyl-2pyrrolidone) under different irradiation conditions provided evidence of improved photoactivity for samples prepared at high pressure, due to the increased active surface area and optimal nitrogen doping levels. Overall, this study showed a simple method to produce highly controllable nitrogen doping in different sites within TiO 2 showing improved visible light photoactivity and photo induced pollutant degradation. More interestingly, by investigating the effect of different nitrogen sites in nitrogen doped TiO 2, we have shown that the optimized conditions for photocatalysis do not correspond to those for water splitting.

Statistically designed amphiphilic copolymer coatings were deposited onto Thermanox, Si wafer, and quartz crystal microbalance (QCM) substrates via Plasma Enhanced Chemical Vapor Deposition of 1H,1H,2H,2H-perfluorodecyl acrylate and diethylene glycol vinyl ether in an Inductively Excited Low Pressure Plasma reactor. Plasma deposited amphiphilic coatings were characterized by Field Emission Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, Atomic Force Microscopy, and Water Contact Angle techniques. The surface energy of the coatings can be adjusted between 12 and 70 mJ/m(2). The roughness of the coatings can be tailored depending on the plasma mode used. A very smooth coating was deposited with a CW (continuous wave) power, whereas a rougher surface with R(a) in the range of 2 to 12 nm was deposited with the PW (pulsed wave) mode. The nanometer scale roughness of amphiphilic PFDA-co-DEGVE coatings was found to be in the range of the size of the two proteins namely BSA and lysozyme used to examine for the antifouling properties of the surfaces. The results show that the statistically designed surfaces, presenting a surface energy around 25 mJ/m(2), present no adhesion with respect to both proteins measured by QCM.