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International audience; An enzymatic biofuel cell cathode was elaborated by nano-structuration and functionalization of graphite using two consecutive plasma treatments before immobilization of laccase as a biocatalyst to perform oxygen reduction reaction (ORR) by direct electron transfer ((DET). Nano-structuration of graphite surfaces by synthesis of vertical graphen-like carbon nanowalls (CNWs) was performed by microwave excited plasma enhanced chemical vapor deposition (PECVD). Atmospheric pressure plasma jet (APPJ) system was then used to functionalize chemically the CNWs surface via a rapid and dry route. A partial fractional design evidenced two significant parameters of the APPJ treatment in terms of ORR current density: the treatment time and the inter-distance between the plasma jet and the surface of the carbon material. With the optimized APPJ treatment parameters, a four-fold enhancement of the ORR current density (-440 ± 70 µA/cm2) could be obtained on CNWs, compared to graphite electrodes. The best current density obtained was about −1 mA/cm2 with oxidized laccase covalently immobilized on the electrode without any agitation of the solution, confirming the main importance of enzyme orientation on the electrode surface for efficient DET transfer, the relevance of electrode nanostructuration and the advantage of covalent linking of the protein on the electrode surface.

International audience; Hexamethyldisiloxane (HMDSO)/Graphene nanosheets (GNs) nanocomposite coatings were deposited by a dielectric barrier discharge at atmospheric pressure. Commercially available GNs were incorporated into HMDSO precursor at different concentrations up to 2 wt%. The nanocomposite coatings were analyzed using scanning electron microscopy (SEM) and nanoindentation test. Based on SEM images, it was found that the GNs were well distributed and dispersed in the plasma polymerized hexamethyldisiloxane (ppHMDSO) matrix with no significant agglomeration. The results of nanoindentation tests performed with the continuous stiffness measurements mode showed an increase in the hardness and reduced Young's modulus with the increase of graphene nanosheets percentage. The maximum increase was two orders of magnitude for 2% GNs/ppHMDSO nanocomposite coatings compared to the homopolymer ppHMDSO. Furthermore, the creep compliance analysis showed that the nanocomposite coatings exhibited a viscoelastic behavior compared to the plasma polymer homopolymer.

www.springerlink.com; International audience; We report a method to obtain biocompatible PEG copolymer coatings inside High Density Polyethylene (HDPE) and Pyrex tubes, which was successfully developed by using a transporting discharge. The latter being a dry process, it is easier to apply as compared to the conventional multistep wet chemical techniques. The results presented in this paper show that for a 70 cm tube good cell repellent properties as compared to the control was obtained for the entire length of the tube. The best nonfouling properties with respect to CT-26 (colon cancer) were obtained for coatings presenting the best retention of ether functionalities from the DEGME monomer i.e. between 5-25 cm downstream of the tube. These results are interesting for surface modification of biomaterial and biomedical devices which present hollow bodies.

"The final publication is available at link.springer.com"; International audience; In this research work we demonstrated that a helium/oxygen Dielectric Barrier Discharge conferred hydrophilic functional groups onto the surface, which lead to enhanced bioactivity of UHMWPE without affecting the biocompatibility of the polymer. The latter was checked by increased adhesion of fibroblast cells to the polymer. The effects of the He/2% O2 DBD plasma was compared for the first time to a rotating blown arc atmospheric pressure plasma jet (r-APPJ) in air. The results show a better functionalization as well as stability of the surface properties of the films treated with the DBD. The surface modified UHMWPE once immersed in a Simulated Body Fluid induced the formation of nucleus of hydroxyapatite (calcium phosphate) leading to the growth of a thick apatite coating which was followed up to 14 days, which can be expected to be highly bioactive. Surface characterization techniques also showed different chemical moieties in the case of the two different atmospheric discharges. DBD discharge in He/2% O2, leading to more stable polar functions grafted to a crosslinked polymer surface, proved to be more bioactive than UHMWPE treated by a r-APPJ in air. The latter treatment lead to grafting of less oxygen containing groups to the surface as well as to LMWOM created on r-APPJ treated UHMWPE which are unstable in aqueous media used both in SBF and fibroblasts in DMEM.

Plasma processing finds widespread biomedical applications, such as the design of biosensors, antibiofouling surfaces, controlled drug delivery systems, and in plasma sterilizers. In the present coronavirus disease (COVID‐19) situation, the prospect of applying plasma processes like surface activation, plasma grafting, plasma‐enhanced chemical vapor deposition/plasma polymerization, surface etching, plasma immersion ion implantation, crosslinking, and plasma decontamination to provide timely solutions in the form of better antiviral alternatives, practical diagnostic tools, and reusable personal protective equipment is worth exploring. Herein, the role of nonthermal plasmas and their contributions toward healthcare are timely reviewed to engage different communities in assisting healthcare associates and clinicians, not only to combat the current COVID‐19 pandemic but also to prevent similar kinds of future outbreaks., This review presents a comprehensive take on the significance of nonthermal plasma processing as a versatile tool for developing state‐of‐the‐art biomedical and healthcare technologies. Under the spotlight is its immense technological potential to offer apposite solutions for combating viral pandemics like coronavirus disease (COVID‐19), be it in the form of rapid diagnostic tools fabrication, sterilized personal protective equipments (PPEs), drug delivery systems, or antimicrobial and antibiofouling surfaces.

International audience; In this study, micrometer thick Ag‐TiO2 coatings were deposited in a single and facile step by spraying the precursor in an atmospheric pressure plasma jet with different concentrations of Ag nanoparticles. The homogenous distribution of Ag decreased the TiO 2 crystal size and increased the surface area. The coatings were characterized to be porous with an anatase phase with improved charge separation and visible light absorption. The photocatalytic activity of the materials was investigated for degrading rhodamine B using a white lamp as a screening method to optimize Ag‐TiO 2 coatings. Then the photodegradation of trace pharmaceutical compounds (TrPCs) was investigated by using a solar light simulator at the optimal condition of a TiO 2 coating with 0.4wt% Ag

In this work, an open-air arc plasma jet has been studied to polymerize 3-aminopropyelthrietoxysilane (APTES), which is the most commonly used aminosilane to functionalize surfaces with amine groups. Although the discharge produced from air is highly oxidative and the gas temperature is high as compared to other atmospheric plasma sources, amine groups, as well as amide ones, were identified in the nanometers thick coatings by XPS and FTIR analysis. By comparing the results with post-treatment and -grafting experiments, the partial retention of amine groups might be explained by the non-ideal mixing of the precursor flow with the main gas stream inside the plasma jet. Beside the intrinsic plasma reactivity, hydrodynamics effects are indeed important when considering flowing atmospheric plasmas.

International audience; The present study proposes an alternative eco-friendly method to prepare a thin composite coating based on graphene embedded in siloxane polymers which can be used as application for the corrosion protection of steel. The nanocomposite coatings were elaborated by a dielectric barrier discharge using a nebulized colloidal suspension of graphene nanosheets (GNs) dispersed in hexamethyldisiloxane (HMDSO) used as the precursor for the polymer matrix. After obtaining a stable colloidal solution, it was nebulized into the plasma reactor to form a plasma polymer (pp) coating from HMDSO (ppHMDSO) in which GNs were incorporated (GN@ppHMDSO) on the mild steel substrate. The chemical structure of the hybrid coatings was characterized by X-ray photoelectron spectroscopy and Fourier transform infrared spectrometry. Raman spectra of GNs and GN@ppHMDSO coatings suggest the existence of charge transfer between the GNs and the HMDSO matrix. Furthermore, scanning electron microscopy confirms the synthesis of micro/nanocomposite with a fairly homogeneous dispersion of the GNs in the polymer matrix. The corrosion resistance of the samples was evaluated by electrochemical impedance spectroscopy which showed that the hybrid coatings GN@ppHMDSO deposited by a one-step atmospheric pressure plasma process, presented excellent anticorrosion performance with 99.99% of protection efficiency.

International audience; One-dimensional TiO2 nanostructure synthesized using a hydrothermal method showed significant differences in the bandgap energies and crystal phase properties under different synthesis conditions. The objectives of this study were to evaluate the effect of the hydrothermal reaction conditions on the bandgap energy and to optimize the reaction conditions using a 3-factor 3-level Box Behnken design. The factors investigated include temperature, NaOH concentration and TiO2 concentration (BBD). A quadratic response surface model predicted optimum conditions for the maximum and minimum bandgap energy. The BBD analysis and other statistical tools provided evidence showing the temperature and NaOH concentration significantly affected the 1D TiO2 bandgap energy. Pure anatase was associated with a higher bandgap energy, whereas the biphasic anatase-rutile and anatase-TiO2-B phases were linked with decreasing the bandgap energy. In addition, the crystal size and specific surface area (SSA) impact on the bandgap energy was due to the size quantization effect.

STSM grant by COST ACTION MP1101 “Biomedical Applications of Atmospheric Pressure Plasma Technology” is acknowledged. Financial support by Innovaciones DisRas S.L. Company is also acknowledged.

International audience; A pulsed-arc atmospheric pressure air plasma jet has been used to depositplasma polymerized acrylic acid/methylene-bis-acrylamide (ppAA/MBA) organic thinfilms. Optical emission spectroscopy has been performed to investigate the reactivity of theplasma and the dissociation of the precursor as a function of the pulse frequency anddistance from the nozzle. An estimation of the OH rotational temperature, which is anindicator of the plasma gas temperature, has also been performed. By heating the substrateduring deposition, it was possible to improve to a great extent the stability to water of thecoatings. Stable ppAA/MBA films have been obtained with an air plasma over a largerange of pulsed frequencies (from 15 to 25 kHz) when the substrate was heated to 200° C.The composition of these coatings was investigated by FTIR and different amide/acidratios were obtained, showing the possibility to grow stable films with different functionalgroups by adjusting the deposition parameters.

Surface activation of polymers by atmospheric pressure plasma is an economically important process for bonding technologies. Although most of the studies are focused on the modification of the surface chemistry, this study investigates the modification of the topmost surface and the deeper layers of a polyamide-6 sheet treated by an open-air atmospheric plasma jet system. The plasma jet used in this study is a unique combination of highly reactive species (e.g. O8, 8OH. . .) and a high temperature gas estimated (from 600–1 000 K) which leads to surface functionalization,amorphization and polymorphism modification. The results have shown that an amorphization of the polyamide occurs on the top surface. Moreover, a crystallization of the amorphous phase in the a form was also highlighted in the depth of the material.

Water stable plasma polymerized acrylic acid/methylene-bis-acrylamide (ppAA/MBA) thin films have been deposited with an atmospheric pressure air plasma jet, a fast technique to grow organic thin films. To increase the stability of the coatings, a cross-linking agent (MBA) was added to the precursor (AA), which was introduced with a home-made spraying system. The jet speed and pulse frequency of the discharge were investigated regarding the properties of the coatings. Two types of materials were obtained: in low energy conditions (high jet speed and low frequency) the films presented a water-soluble part with a certain organized structure. When more energy is supplied to the growing films, a more polymerized material with a more amorphous structure is obtained. Increasing the energy further leads to the deposition of a more cross-linked film with a better stability to water. In optimized conditions, no weight loss and no significant chemical change were noticed after soaking in water.

A custom made non-equilibrium atmospheric pressure argon plasma jet was developed for the deposition of PEG like coatings in open-air for cell repellent applications. OES and electrical measurements were performed to characterize the discharge. The emission of the N2 (C3Πu–B3Πg) was followed in order to minimize the air entry in the plasma. Surface analyses were carried out on ap-DEG coatings and the best retention of COC was obtained under mild plasma conditions. The ap-DEG coatings were compared with typical LP deposited PEG like coatings. Less retention of COC and therefore less cell repellent properties were observed for ap-DEG coatings as compared to those deposited at low pressure.

International audience; Thin films of fluorocarbon were deposited on polyethersulfone membranes via argon plasma sputtering of a poly(tetrafluoroethylene) (PTFE) target in an RF magnetron plasma reactor. The obtained deposited ultrathin coatings had nanoscale roughnesses and high degrees of fluorination. The intensity of fluorine atom in plasma environment during fluorocarbon deposition was investigated. Depending on the deposition conditions comprising working gas pressure, applied RF power, and distance between the target and the substrate, polymeric films with different chemical compositions and/or morphologies were obtained. The morphologies of the films were analyzed by means of SEM, XPS, and AFM. The results suggested that the sputtered film deposited at a higher pressure and longer target–substrate distance and moderate RF power had a surface composition and chemical structure closer to those of the PTFE film. The treated hydrophobic PES membranes with water contact angles as high as 115° were applied for the first time in an air gap membrane distillation setup for removal of benzene as a volatile organic compound from water. The results showed that the plasma-treated membranes have a comparable or superior performance to that of commercial PTFE used in membrane distillation with similar permeate flux and separation factor after 20 h long term performance.

International audience; In this article, we developed transporting plasma sources that operate at atmospheric pressure. The effect of electrode configuration on plasma transporting was investigated. In order to increase the transporting plasma cross-section, we converted a plasma stream into four plasma channels by a cylindrical housing. Electron excitation and rotational temperatures were estimated using optical emission spectroscopy. Furthermore, the electrical and temporal characteristics of the plasma, discharge power and charge deposition on the target were investigated. The propagation characteristics of single and multi-channel transporting plasma were compared with the same cross-sectional area. Two configurations for multi-channels were designed for this purpose. Escherichia coli bacteria were exposed to the single and multi-channel transporting discharge for different time durations. After exposure, the results indicated that the inactivation zones were significantly increased by a multi-channel transporting plasma. Finally, E. coli inactivation by those plasma apparatuses was compared with that of several standard antimicrobial test discs such as Gentamicin, Tetracycline, Amoxicillin and Cefixime.

The surface properties of polydimethylsiloxane (PDMS) were modified by treatment with an atmospheric pressure rotating plasma jet (APPJ) and the surface modifications were studied to assess its hydrophilicity and adhesion to acrylic adhesive tape intended for medical applications. Furthermore, the extent of hydrophobic recovery under different storage conditions was studied. The surface treatment of PDMS with the APPJ under optimal conditions noticeably increased the oxygen content and most of the surface silicon species were fully oxidized. A brittle silica-like layer on the outermost surface was created showing changes in topography due to the formation of grooves and cracks. A huge improvement in T-peel and the shear adhesive strength of the APPJ-treated PDMS surface/acrylic tape joints was obtained. On the other hand, the hydrophilicity of the PDMS surface increased noticeably after the APPJ treatment, but 24 h after treatment almost 80% hydrophobicity was recovered and the adhesive strength was markedly reduced with time after the APPJ treatment. However, the application of an acrylic adhesive layer on the just-APPJ-treated PDMS surface retained the adhesive strength, limiting the extent of hydrophobic recovery. The STSM Grant by COST ACTION MP1101 ‘Biomedical Applications of Atmospheric Pressure Plasma Technology’ and financial support from the Innovaciones DisRas S L Company is gratefully acknowledged.

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.

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.

Environmentally benign-solvent free plasma process is employed to produce nanostructured PFDA-co-DEGDME amphiphilic coatings via plasma co-polymerisation of 1H,1H,2H,2H-perfluorodecyl acrylate (PFDA) and diethyleneglycol dimethyl ether (DEGDME) precursors in a low pressure-RF-inductively excited tubular plasma reactor using argon as a carrier gas. The plasma-polymerised coatings are characterised by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and contact angle measurements. PFDA-co-DEGDME coatings with varying chemical environments and morphologies are achieved by varying the plasma parameters such as, continuous wave (CW) and pulse modulated (PM) plasma mode, and plasma deposition time. Plasma polymerised PFDA-co-DEGDME coatings are found to exhibit a switching property in terms of wettability, i.e., from hydrophobic to hydrophilic and vice versa, in response to the contacting environment. Quartz crystal microbalance (QCM) is used to study the adhesion of two model proteins, namely, human serum albumin (HSA) and fibrinogen (FGN) in continuous flow conditions, which reveals the protein repellent, i.e., anti-biofouling characteristics of the PFDA-co-DEGDME amphiphilic coatings.

Low surface energy fluorocarbon polymer coatings were prepared via plasma enhanced chemical vapor deposition (PECVD) of 1H,1H,2H,2H-perfluorodecyl acrylate (PFDA) in a low pressure inductively excited RF plasma. The influence of plasma parameters, such as, deposition time, continuous wave (CW) and pulse modulated (PM) plasma mode, plasma power and plasma duty cycle (DC) on morphology and wettablity of the PFDA was investigated using field emission scanning electron microscopy (FESEM) and contact angle (CA) measurement techniques. The plasma mode, plasma power and pulse duty cycle played a pivotal role in tailoring the surface morphology, wettability and the surface energy of the PFDA coating. The water CA hysteresis values for PFDA coatings suggested the wetting characteristics of the coating satisfying Wenzel model of nanostructured solid-water wetted contact. A thin conformal PFDA coating transformed a super-hydrophilic Whatman filter paper into a super-hydrophobic and oleophobic surface, which has industrial applications for development of durable, stain resistance and liquid repellent papers. The antifouling property of PFDA coatings investigated by quartz crystal microbalance (QCM) exhibited the protein repellent behavior against three model proteins namely, ovalbumin (OVA), human serum albumin (HSA) and fibrinogen (FGN).

International audience; Polypropylene (PP) particles are used for various purposes, however, the good mechanical properties of PP are counterbalanced by a poor wettability. The wettability of PP particles was therefore improved by an atmospheric pressure blown‐arc air plasma jet treatment in a new designed homemade Wurster fluidized bed reactor (Wurster‐FBR). This reactor, was used to treat 200 g of particles per batch. The surface free energy of PP particles determined by the Zisman method showed an increase from 30.7 to 38.6 mN m−1 after 120 s of treatment. XPS results showed a 5% increase of the atomic concentration of oxygen on the surface of the treated particles. In order to describe the process, a 2D axisymmetric non‐isothermal k‐ϵ turbulent model was used to determine the velocity field, pressure, and temperature profile of the gas phase inside the reactor. Furthermore an Eulerian‐Eulerian multiphasic CFD model was added to determine the dynamics of the particles inside the reactor, and the results were compared with fast imaging, thermocouple, and anemometry measurements. These investigations are very important to monitor the homogeneity of the particle treatments, to determine the average effective treatment time for each particle and to avoid overheating of thermally sensitive PP.

International audience; A novel hydrophobic membrane was developed by means of plasma polymerization of the polyethersulfone (PES) membrane using ethylene as the precursor to obtain appropriate performance in the membrane distillation (MD). The effects of plasma treating parameters including duration time, gas pressure, and power on the surface properties of the treated membranes as well as their MD performances were discussed. The surface properties of the treated samples were evaluated in terms of the surface morphology, chemistry, porosity and pore size, roughness, hydrophobicity, and Liquid Entry Pressure (LEP). The treated hydrophobic PES membranes with water contact angles of as high as 115° were obtained at high pressures and moderate powers. Response surface methodology was applied for modeling and optimization of the Air Gap Membrane Distillation (AGMD) system to separate benzene as a volatile organic compound from water. The plasma treated membranes showed fluxes at least as high as those of the commercial polytetrafluoroethylene (PTFE) membranes.

The thin film deposition in DBDs fed with Ar/HMDSO/O2 mixtures was studied by comparing the FT-IR spectra of the deposits with the GC-MS analyses of the exhaust gas. Under the experimental conditions investigated, oxygen addition does not enhance the activation of the monomer while it highly influences the chemical composition and structure of the deposited coating as well as the quali-quantitative distribution of by-products in the exhaust. Without oxygen addition a coating with high monomer structure retention is obtained and the exhaust contains several by-products such as silanes, silanols, and linear and cyclic siloxanes. The dimethylsiloxane unit seems to be the most important building block of oligomers. Oxygen addition to the feed is responsible for an intense reduction of the organic character of the coating as well as for a steep decrease, below the quantification limit, of the concentration of all by-products except silanols. Some evidences induce to claim that the silanol groups contained in the deposits are formed through heterogeneous (plasma-surface) reactions.

We present a process for rapid post-discharge deposition of liquid monomer to form functional coatings at atmospheric pressure. The post-discharge polymerization of dense polyacid and polyether coatings is first depicted versus the energy density deposited by the preliminary surface treatment of polyethylene and polystyrene substrates in air Dielectric Barrier Discharge (DBD) with respect to SEM, to XPS and FTIR-ATR analysis and to polymerization yield determined by mass measurements. The paper focuses on the effect of the filamentary air DBD on surface of the polymer substrates and on post-discharge polymerization mechanism. Indeed, the grafting yield is shown to depend on the energy density deposited by DBD and on the time exposure to air between DBD and monomer deposition, controlling respectively the surface density of radicals and labile peroxides, both triggering the polymerization of vinyl precursors. Then, the effect of deposition conditions on the polymerization yield and related thickness of the functional polymer coatings is shown and special attention is paid to the stability of the coating upon washing.

The aim of this work was to test and to compare different methods reported in the literature to quantify amine and aldehyde functions on the surface of polyethylene (PE) films treated by ammonia plasma and to specify their stability against time. A low pressure ammonia plasma reactor was used to functionalize PE films with amine groups, which could be subsequently used for further immobilization of biomolecules. In order to determine the density of amine groups on the surface of treated films, various molecule probes and spectrophotometric analytical methods have been investigated. Two methods using (i) sulfosuccinimidyl 6-[3'-(2-pyridyldithio)-propionamido] hexanoate (sulfo-LC-SPDP) and (ii) 2-iminothiolane (ITL) associated with bicinchoninic acid (BCA) have been proved to be reliable and sensitive enough to estimate the surface concentration of primary amine functions. The amount of primary amino groups on the functionalized polyethylene films was found to be between 1.2 and 1.4 molecules/nm2. In a second step, the surface concentration of glutaraldehyde (GA), which is currently used as a spacer arm before immobilization of biomolecules, has been assessed: two methods were used to determine the surface density of available aldehyde functions, after the reaction of GA with the aminated polyethylene film. The concentration of GA was found to be in the same range as primary amine concentration. The influence of aging time on the density of available amino and aldehyde groups on the surfaces were evaluated under different storage conditions. The results showed that 50% of the initial density of primary amine functions remained available after storage during 6 days of the PE samples in PBS (pH 7.6) at 4 degrees C. In the case of aldehyde groups, the same percentage of the initial density (50%) remained active after storage in air at RT over a longer period, i.e., 15 days.

Hexamethyldisiloxane was used to deposit silicon dioxide thin films using a low frequency plasma reactor at low pressure as well as a dielectric barrier discharge (DBD) at atmospheric pressure. FT-IR, XPS, EIS, SEM and ellipsometry were used to analyse the samples. The results show that, at low pressure, the deposited films which are smooth, continuous and dense present a polymer-like structure. By carrying out the film deposition after an oxygen plasma pretreatment step, a further improvement in the protective properties is achieved, which is observed in the case of SiOχ coatings with 13.56 MHz RF generators.1 At atmospheric pressure, the deposited films present an inorganic character deposited in open air and a polymer-like one deposited under a controlled nitrogen atmosphere in our DBD reactor. The latter also allows continuous films which present the best anti-corrosive properties (which have been studied for the first time for anti-corrosive properties) when they contain some carbon incorporated.

In this paper plasma processing of polymer films and particles is examined by coating and noncoating plasmas. OTS-SAM (octadecyltrichlorosilan self-assembled monolayers) grafted to silicon wafers were used as a model to mimic the structure of PE. The authors believe that the difference by a factor of three in the etching rate between SAM and PE films in ammonia plasma is the consequence of their quasi-crystalline arrangement, compared to the amorphous PE films. For the surface treatment of polymer particles a fluidized bed low pressure plasma has been used. With the help of LDA (Laser Doppler Anemometry) measurements the real time during which the particles were exposed to the plasma was determined. A coating plasma such as allylamine was used to obtain tailored material presenting amino groups on particles. The development of the quantitative chemical derivatization assisted by UV–Visible measurements showed that it was possible to incorporate up to a maximum of 110 nmol of amino groups per gram of powders under specific conditions. Moreover, by using appropriate blocking agents, this derivatization technique allows to differentiate between primary, secondary and tertiary amino groups.

A line-shaped atmospheric pressure filamentary plasma is developed to carry out the open air deposition of silicon oxide films from N 2 /hexamethyldisoxane (HMDSO) mixtures with/without adding oxygen. FT-IR, XPS, SEM, and ellipsometry were used to analyse the samples. It is found that the deposited films present mainly inorganic characteristics even without an oxygen admixture in the open air system. Smooth, continuous, and uniform films can be formed at relatively low monomer content. By increasing the monomer content for a fixed power density or oxygen in the input gases, the deposition rates increase and then show a plateau, suggesting that there exists saturation values for the deposition rates corresponding to the monomer and oxygen content. By the comparison of films deposited in the open air device and in a controlled nitrogen atmosphere in the same device, the important role of the oxygen in the open air reactor has been shown. This study exhibits a potential of open air deposition at atmospheric pressure to form SiO 2 films for large-scale deposition.

Threshold ionization mass spectrometry (TIMS) has been used to measure the excited molecular oxygen states O2 (1Δg) and during plasma-assisted chemical vapour deposition of tin oxide (SnO2) thin films. The latter, composed of nanosized features, was deposited by feeding in a mixture of Ar, O2 and tetramethyltin (Sn(CH3)4 or TMT) in a capacitively coupled RF discharge reactor. Langmuir probe measurements were performed along with TIMS to measure the electron temperature and density. The correlations between these two diagnostic methods have been investigated. The observed densities of O2 (1Δg) and in the γ mode of the discharge are maximum at a low electron temperature and high density. Furthermore, these results have been shown to be correlated to the trend of the electronic conductivity of the deposited SnO2 thin films.

Chemical functionalities, topography and adherence between Al and polyethylene terephthalate (PET) films, modified by laser treatment below the polymer ablation threshold fluence in air and in helium at different wavelengths, fluences, pulse numbers and by low pressure plasma treatment in He 95% with O2 5%, at 0.2 W/cm3 were investigated by XPS, AFM, water contact angle and adhesion measurements. XPS results revealed (i) formation of polar-oxygenated functional groups (C O, O C O) by laser treatments in air and (ii) incorporation of ester and ether groups by plasma treatment in He 95% with O2 5%. After deposition of thermally evaporated Al on laser or plasma treated PET films, U-Peel tests indicated that laser treatment in air at 248 nm and 20 mJ/cm2, and plasma treatment improved Al/PET adhesion. XPS studies revealed the presence of an increasing number of Al O C stable and cohesive interfacial complexes formed by chemical interaction between aluminium and the laser treated in air or plasma treated in He 95% with O2 5% PET films. These interfacial compounds play an important role in the enhancement of the metal/polymer adhesion.

Summary: Thin films of plasma-polymerized allylamine (PPAA) have been deposited onto polyethylene powders (PE) and polystyrene (PS) beads by using a low-pressure 13.56 MHz plasma in a fluidized bed reactor. Chemical derivatization using a set of three different blocking agents has allowed quantitative measurement of the relative percentages of primary, secondary, and tertiary amines. Under optimized conditions, it is possible to incorporate up to 110 nmol of amine groups per gram of powder and with a selectivity of 75% for primary amines. Moreover, our data clearly show that for films deposited at 10 W the selectivity for primary amines is at a maximum, but this is at the expense of resistance to washing. A power of 20 W corresponds to an optimum value since both the amount of primary amines and the degree of resistance of the coating to solvents reach maximum values. Distribution of the primary (I), secondary (II), and tertiary (III) amine groups on plasma-polymerized allylamine films deposited on polyethylene powders.

We report the self-organized nanostructures of hydrogen-free amorphous carbon (a-C) with controllable characteristic length scales obtained by using ion beam assisted deposition. By selecting various temperature regimes, two kinds of nanostructure, mounds and ripples, are successfully formed. For the growth temperature of 200 °C, the fractal analysis of the surface shows that the lateral characteristic length for mounding structures increases with increasing ion energy. But for ripple structures formed in the relatively high temperature region, the ripple wavelengths are found to show a nonlinear dependence on the ion energy. Further, at certain temperatures there exist energy thresholds for stopping the formation of ripple structures. These results demonstrate that the characteristic scales of nanostructures for a-C can be significantly controlled through the tuning ion energy in a well-defined manner.

A global plasma model is used to investigate the chemistry and energy deposition in 13.56 MHz radio-frequency capacitively coupled oxygen–argon discharges under conditions usually used for the deposition of tin oxide films. These models are based on the solution of a stationary electron Boltzmann equation coupled to species balance equations including the vibrational kinetics equations of O2. The results obtained showed that vibrational non equilibrium of O2-molecule is not significant. The dissociation degree of O2 was found to be around a few percents and the discharge was often moderately electronegative even for small O2 contents in the feed gas. The ionization and energy dissipation mechanisms are mainly governed by the collisional processes involving O2 for an oxygen feed gas composition greater than 20%. Results also showed that the predicted densities of the charged species and the electronegative character of the discharge are strongly linked to the assumption made on the homogeneity of the power deposition. On the contrary, the predicted density of O-atom is not sensitive to this assumption.

The purpose of this work was to investigate the influence of a low-pressure, low-frequency ammonia plasma treatment on the wettability of polypropylene (PP) thin films and its consequences on the adhesion properties of such treated films to thermally evaporated aluminium coatings. The wettability was determined by contact angle measurements while the adherence was evaluated by a U-Peel test especially suited to thin flexible substrates with thin metallic layers. Furthermore, an image processing system was used to measure the percentage of the peeled-off metal. Measurements carried out on NH3 plasma-treated PP films revealed a sharp increase in the wettability and in the adhesion properties for treatment times as short as 1 s. Electron-induced X-ray emission spectroscopy and X-ray photoelectron spectroscopy showed the formation of new chemical bonds at Al/NH3 plasma-treated PP film interfaces. The new types of bonds have been characterized by well-defined chemical states (C–NHx, CO–NH, Al–N–C) in the N 1s (and C 1s) spectra. The interfacial complexes Al–N–C and Al–N–CO are formed by the NH3 plasma treatment which creates at the PP surface active sites (N(C–NHx) and N(CO–NH)) which react with the evaporated aluminium atoms. These interfacial bonds play an important role in the enhancement of the metal/polymer adhesion.

International audience; In this work, the surface modification of ultra‐high‐molecular‐weight polyethylene (UHMWPE), a linear polymer, by a helium transporting discharge at atmospheric pressure was investigated by means of FTIR, AFM, XPS, ToF‐SIMS, and contact angle measurements. Two types of discharge configurations, that is, jet and glow of the transporting discharge for the surface treatment of polymer substrates were studied. The results show that the position of the UHMWPE polymer substrates plays an important role in the surface modification and stability of the treatment. The polymer substrates placed inside the transporting discharge tube present more stable wettability and surface modification. In addition, the transporting discharge was used to modify the inner surface of the high density polyethylene tube.

International audience; In this paper, it is reported that composition of an atmospheric pressure nitrogen plasma jet is influenced by the nozzle material. Using optical emission spectroscopy and camera observations, it is shown that using a stainless steel nozzle, induces an orange nitrogen emission, whereas a quartz nozzle leads to blue nitric oxide emission, due to the nitridation and oxygen exchange between the reactive nitrogen plasma and the SiO2 surface.

International audience; A simple method to deposit photocatalytic TiO2 coatings, at a high rate (20–40μms−1), andwith a high porosity, is reported in this paper. This method, which allows the treatment ofmembranes (with an 800 nm pore size), is based on the introduction of a liquid precursorsprayed into an open-air atmospheric pressure plasma jet (APPJ). The photocatalytic activityof the TiO2 thin films prepared by APPJ have been compared with our best N-doped TiO2 thinfilms, deposited by reactive radio frequency (RF) magnetron sputtering, previously reported inthe literature. The morphology, chemical composition, photoelectrochemical, andphotocatalytic properties of the coatings have been studied in this paper. Significant control ofthe porosity and crystallinity was achieved by varying the deposition parameters and theannealing temperature. Under optimized conditions, the TiO2 coatings deposited by APPJ arecharacterized by a higher photocatalytic activity as compared to the optimized thin filmsdeposited by RF sputtering. This difference can be explained by the higher specific surface ofthe APPJ coatings. Finally, the most interesting characteristic of this APPJ-liquid spray processis its capacity to treat membranes without blocking the pores, and to produce photocatalyticmembranes which can efficiently combine filtration and photocatalysis for water treatment.

This paper deals with the plasma surface treatment of polymers in a low frequency bell jar reactor with non-symmetrical configuration of electrodes. The highly energetic character of this discharge due to its low excitation frequency and electrode configuration, as well as its small discharge volume makes it a very efficient and fast functionalization process. Amongst the different plasma gases used for the adhesion improvement of polypropylene to aluminum, ammonia has shown to be the most suitable one for this application. Since the NH and NH2 radicals play an important role in the kinetics of nitrogen incorporation in polymers, mixtures of N2 and H2 were also used as possible substitutes for ammonia. The former are more environmentally friendly and easier to handle in industry than ammonia. The efficiency of nitrogen rich mixtures in the case of the second application, i.e. adhesion improvement of copper to fluoropolymers has been compared to that of ammonia which still shows faster nitrogen incorporation. The last part of this paper is devoted to the study of the energetic character of plasmas of mixtures of He+NH3 by OES and electrical measurements in the whole range of composition of the two gases. The results show that an ammonia percentage ranging from 5 to 10% in plasmas of mixtures of He/NH3 represents a transition between two different discharge regimes. Plasmas of mixtures of He+2% NH3, characterized by highly energetic electrons, ions and probably metastables of helium give rise to enhanced adhesion of PP to aluminum which remains stable with time.

We describe a method based on plasma polymerization for the modification and control of the surface properties of poly(dimethylsiloxane) (PDMS) surfaces. By depositing plasma polymerized acrylic acid coatings on PDMS, we succeeded to fabricate stable (several days) hydrophilic and patterned hydrophobic/hydrophilic surfaces. We used this approach to generate direct and (for the first time in this material) double emulsions in PDMS microchannels.

The physicochemical properties of ammonia-treated polypropylene films have been studied using some analytical techniques. The acid-base properties of treated surfaces were analyzed by X-ray photoelectron spectroscopy (XPS) in conjunction with the molecular probe technique and using chloroform as reference Lewis acid. The results show a basic character for treatment times lower than 1 s. This property disappears for longer treatment times showing less specific interaction sites accessible at the surface. These results are confirmed by ToF-SIMS and are in agreement with wettability studies and adhesion phenomena with aluminium. The new application of capillary electrophoresis ion analysis (CIA) permitted us to identify the acidic low molecular weight fragments formed at the plasma-treated surface and found them to be fumaric and malic acids.

International audience; SnO2:F thin films were deposited on polycarbonate and glass substrates by RF capacitively coupled plasma enhanced chemical vapor deposition (PECVD) using a mixture of tetramethyltin (TMT) [Sn(CH3)4], argon, oxygen as precursors. The effects of the substrate temperature, deposition time and doping on the resistivity and the morphology of the films have been studied. The as-deposited films appear to have higher carrier mobilities than amorphous ones, in the range of 5 and 7.5 cm2 · V−1 · s−1, which could be explained by the presence of nanocrystallites. In order to understand the nanostructure of the films, we studied the formation of nanoparticles and dust particles in the discharge. Finally, we have shown that the incorporation of less than 3% of F in the tin oxide layer could decrease the resistivity down to 3 · 10−3 Ω · cm.