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Objetivo. La presente investigación tiene como objetivo analizar la resiliencia individual, organizacional y comunitaria del docente en contextos vulnerables desde la revisión descriptiva de la literatura. Métodos. Para el proceso de recolección de datos se utilizaron las bases de datos Scielo, Scopus, Proquest, Web of Science (WoS), ScienceDirect, fueron seleccionados 20 artículos de investigación originales publicados entre 2015 y 2021, siendo incluidos artículos cuantitativos y cualitativos. Los criterios de inclusión fueron: artículos de contextos vulnerables, situaciones de estrés, pandemia COVID-19, situación de pobreza, desastres naturales, entre otros; y como estrategia de análisis se ordenaron de manera conceptual y por categorías, se clasifcaron los resultados y compararon los conceptos, para poder ser redactados y presentados. Resultados. La resiliencia es una aptitud de sostenibilidad, afronte y recuperación en situaciones de adversidad que comprende capacidades como: flexibilidad, adaptabilidad, vulnerabilidad, ingenio, agilidad, redundancia, fortaleza, tolerancia y colaboración. El docente resiliente transmite un buen clima y culturaorganizacional; un docente resiliente dentro de un contexto vulnerable transmite a sus estudiantes herramientas de afronte, en conjunto con sus recursos personales, llegando a ser participe y promoviendo la resiliencia dentro de la comunidad en la que se desarrolla. Conclusiones. Se concluye que la resiliencia es una capacidad para superar obstáculos y poder adaptarse favorablemente, permitiendo al profesional docente actuar positivamente en el climay la cultura institucional, por lo que necesita ser desarrollada y propiciada por las organizaciones estatales para ser transmitida a la comunidad estudiantil (padres, maestros y estudiantes).

International audience; Dendritic cells (DC) are the most potent antigen-presenting cells and are fundamental for the establishment of transplant tolerance. The Dendritic Cell-Specific Intracellular adhesion molecule-3-Grabbing Non-integrin (DC-SIGN; CD209) receptor provides a target for dendritic cell therapy. Biodegradable and high-surface area porous silicon (pSi) nanoparticles displaying anti-DC-SIGN antibodies and loaded with the immunosuppressant rapamycin (Sirolimus) serve as a fit-for-purpose platform to target and modify DC. Here, we describe the fabrication of rapamycin-loaded DC-SIGN displaying pSi nanoparticles, the uptake efficiency into DC and the extent of nanoparticle-induced modulation of phenotype and function. DC-SIGN antibody displaying pSi nanoparticles favourably targeted and were phagocytosed by monocyte-derived and myeloid DC in whole human blood in a time- and dose-dependent manner. DC preconditioning with rapamycin-loaded nanoparticles, resulted in a maturation resistant phenotype and significantly suppressed allogeneic T-cell proliferation.

There is a strong demand for techniques that allow the fabrication of biocompatible porous nanoparticles for drug delivery applications. In this work, a new method to fabricate size- and shape-controlled porous silicon (pSi) nanodiscs is described. The process relies on a combination of colloidal lithography and metal-assisted chemical etching. Height and diameter of the pSi nanodiscs can be easily adjusted. The nanodiscs are degradable in physiological milieu and are nontoxic to mammalian cells. In order to highlight the potential of the pSi nanodiscs in drug delivery, an in vitro investigation that involved loading of nanodiscs with the anticancer agent camptothecin and functionalization of the nanodisc periphery with an antibody that targets receptors on the surface of neuroblastoma cells is carried out. The thus-prepared nanocarriers are found to selectively attach to and kill cancer cells Refereed/Peer-reviewed

International audience; In this work the structure-property relationships of SiCxNy(O):H gas separation membranes prepared by PECVD is investigated. X-ray photoemission spectroscopy, fast Fourier transform infra-red spectroscopy and X-ray reflectometry are used to determine both the atomic and chemical bond concentrations in the PECVD membrane materials. Coupling these experimental data with a continuous random network model (cluster approach), a 3D molecular description of the material is proposed. It is shown that such approach can depict the composition and the electronic density of the PECVD Sic(x)N(y)(O):H, thus providing description of material porosity that accounts for the measured gas transport properties of both He and N-2 through the membranes.

In the highly competitive market of fuel cells, solid alkaline fuel cells using liquid fuel (such as cheap, non-toxic and non-valorized glycerol) and not requiring noble metal as catalyst seem quite promising. One of the main hurdles for emergence of such a technology is the development of a hydroxide-conducting membrane characterized by both high conductivity and low fuel permeability. Plasma treatments can enable to positively tune the main fuel cell membrane requirements. In this work, commercial ADP-Morgane® fluorinated polymer membranes and a new brand of cross-linked poly(aryl-ether) polymer membranes, named AMELI-32®, both containing quaternary ammonium functionalities, have been modified by argon plasma treatment or triallylamine-based plasma deposit. Under the concomitant etching/cross-linking/oxidation effects inherent to the plasma modification, transport properties (ionic exchange capacity, water uptake, ionic conductivity and fuel retention) of membranes have been improved. Consequently, using plasma modified ADP-Morgane® membrane as electrolyte in a solid alkaline fuel cell operating with glycerol as fuel has allowed increasing the maximum power density by a factor 3 when compared to the untreated membrane.

Silicon carbonitride thin films have been deposited by plasma enhanced chemical vapor deposition (PECVD) from bis(dimethylamino) dimethylsilane (BDMADMS) as a function of X=(BDMADMS/(BDMADMS+NH3)) between 0.1 and 1, and plasma power P (W) between 100 and 400 W. The microstructure of obtained materials has been studied by SEM, FTIR, EDS, ellipsometrie, and contact angle of water measurements. The structure of the materials is strongly depended on plasma parameters; we can pass from a material rich in carbon to a material rich in nitrogen. Single gas permeation tests have been carried out and we have obtained a helium permeance of about 10(-7) mol m(-2) s(-1) Pa-1 and ideal selectivity of helium over nitrogen of about 20. (C) 2010 Elsevier B. V. All rights reserved.

International audience; A plasma polymerization process using a continuous glow discharge has been implemented for preparing proton conducting membranes from trifluoromethane sulfonic acid and styrene. The chemical and physical structure of plasma membranes has been investigated using FTIR and SEM. The films are homogeneous with a good adhesion on commercial gas diffusion layer (E-Tek®). Their deposition rate can be increased with increasing flow rate and input power. The thermogravimetric analysis under air of plasma polymers has showed a thermal stability up to 140 °C. Compared to the pulsed glow discharge studied in a previous paper, the continuous glow discharge has enabled to enhance the proton conductivity of membranes by a factor 3 (up to 1.7 mS cm−1). Moreover, the low methanol permeability (methanol diffusion coefficient down to 5 × 10−13 m2 s−1) of membranes has been confirmed by this study. In an industrial context, a reactor prototype has been developed to manufacture by plasma processes all active layers of fuel cell cores to be integrated in original compact PEMFC or DMFC.

A complete PECVD process for the plasma polymerization of miniature proton exchange membranes (PEM) is presented. Styrene and trifluoromethane sulfonic acid are used as plasmagen precursors in a capacitive coupled low pressure discharge. The process is monitored by impedance probe measurements to ensure stability and reproducibility. FTIR analyses show that such membranes are mainly made up of a polystyrene-like matrix with grafted sulfonic acid groups, which proportion is tuneable as a function of the plasma parameters. The best results in term of deposition rate, monomer structure retention and PEM performances are obtained under pulsed plasma conditions, enhancing radical processes compared to continuous plasma. Because of their thinness and cross-linked structure, such membranes exhibit a similar proton conduction ability and a methanol permeability reduced by a factor 150 compared to Nafion®. SEM observations show a good compatibility of plasma polymerized membranes whatever the substrate is. Consequently, PECVD process enables their better integration in micro fuel cells compared to conventional spin coating method.

Recent advances in miniaturization technology make polymer electrolyte membrane fuel cells very attractive as power sources for portable devices. Ion-exchange membranes for microscale fuel cells are synthesized by plasma polymerization (using a precursor containing ion-exchange groups) and intensively characterized. Ion-exchange plasma membranes are thin, amorphous, and dense materials with no defects. Spectroscopic analyses reveal a polymer-type matrix containing a rather high concentration of ion-exchange groups. Under the best synthesis conditions, membranes show a satisfying ionic conduction level and a high compatibility with other active layers of fuel cells, making them suitable for insertion in such power-supply devices.

Les procedes plasma ont ete initialement developpes pour la microelectronique dans les annees 50. Ils representent une technologie a la fois propre, produisant peu ou pas d'effluents, et extremement souple dont l'equipement de base permet d'atteindre des objectifs aussi divers que singuliers en termes de proprietes d'usage specifiques. Forts de ces avantages, ils sont aujourd'hui utilises dans de nombreux domaines de la chimie des materiaux, notamment pour la modification ou la synthese de membranes. Selon la nature du gaz precurseur du plasma et par le choix de conditions operatoires adequates, il est possible par de tels procedes, de realiser des traitements de surface (par reticulation, greffage et/ou gravure) en vue de modifier les proprietes de surface (rugosite, adhesion, hydrophobie...) de membranes polymeres, ou d'elaborer des couches minces inorganiques ou hybrides de grandes stabilites chimique et thermique. Cet article presente trois nouveaux procedes plasma developpes en laboratoire et destines a modifier ou synthetiser des membranes «sur mesure »: la modification de surface de membranes par des plasmas de gaz fluores, et l'utilisation du procede en configuration depot pour la preparation de membranes pour la separation de gaz et de vapeurs d'une part, de membranes a conduction ionique pour micro piles a combustible d'autre part.

Results of investigations conducted with membranes of several pore diameters are presented: nylon (5 µm), PDVF(1 µm), and polysulfones (1.2 and 3 µm) exposed to a N2 flowing (1 Ln · min−1) microwave (100 W) post discharge, produced at low gas pressure: 130 to 4 000 Pa (1 to 30 Torr). The transmissions of N atoms through these membranes were measured from the intensity variation of the N2, 1st position afterglow before and after the membranes. It appeared that N atoms penetrate and cross the membranes with a transmission factor varying from 20 to 50% for nylon and from 50 to 100% for PDVF and from 33 to 100% for polysulfones during the exposure time (

Sulfonated polystyrene-type membranes were synthesized by plasma polymerization of a mixture of styrene and trifluoromethane sulfonic acid monomers in a low-frequency after-glow discharge plasma reactor. Such a deposition process enables the preservation of the monomers structure, which was confirmed by mass spectrometry analysis. The synthesized plasma-polymerized membranes are dense and uniform with a few microns thickness. Their structure determined by Fourier-transform infra-red spectroscopy and X-ray photoelectron spectroscopy is very rich in sulfonic acid groups (up to 5%) and stable up to 120 °C. Even if their intrinsic proton conductivity is low (10 −1 mS cm −1 ), directly related to their disorganized and highly cross-linked structure, plasma-polymerized membranes present a proton conduction ability similar to Nafion ® because of their low thickness. Due to their highly cross-linked structure, these membranes enable a reduction of the methanol crossover in a factor 10 by comparison with Nafion ® . Thus, the integration of plasma-polymerized films in miniaturized direct methanol fuel cells as proton-exchange membranes seems promising.

Horseradish peroxidase (HRP) was immobilized onto hydrophobic polypropylene microfiltration membranes (PPMMs) through physical adsorption. Effects of incubation time and initial HRP concentration were tested and the most appropriate condition was determined to be 24 h of incubation in 0.3 mg/mL HRP solution. However, the hydrophobicity of the PPMM can be a source of protein denaturation. Then, four surface modifications were conducted to enhance the hydrophilic character of the support and thus the efficiency of HRP immobilization. Results revealed that surface modification with functional groups such as glucoside, polypeptide or amino groups improved the enzyme stability and particularly allylamine plasma treatment led to the highest membrane activity. Then two more methods were used to link HRP onto allylamine plasma treated PPMM (AAMP-PP), such as glutaraldehyde linkage via reaction with amino groups and molecular recognition via biotin–avidin interaction. The results demonstrated that more HRP could be immobilized onto AAMP-PP membranes. In addition, higher membrane activity was observed when the HRP was fixed through chemical reaction and almost 60 times larger when the HRP was attached by molecular recognition. The storage stability of immobilized HRP through biotin–avidin recognition was much higher than those through adsorption or glutaraldehyde binding, almost similar to the free HRP in buffer solution. This means that the immobilization route was to some extent a parameter of more importance than the membrane surface treatment and presumably that biotin–avidin method on allylamine plasma treated PPMM provided a more favorite environment for HRP molecules to keep their natural conformation holding most of their activity.

Plasma polymerization is a very powerful technique for preparing very thin highly cross-linked polymeric films. As in the case of classical polymers, the gas permeation performances of plasma polymers are strongly related to their chemical composition and structural properties. These properties depend directly on the precursor nature and on the operating conditions of the polymerization process like temperature, monomer flow rate, discharge power, frequency, etc. Previous results obtained by our group show that it is difficult to apply the classical Fick's correlations between the permeability, sorption and diffusion to this type of polymer. In addition, their structure, which is not very well known, is very cross-linked, high disordered and behaves like a complex material with two components: a rubber and an inorganic part. Indeed, these polymers cannot be represented as a regular repeat of monomer units. A mathematical model inspired from the free volume concept and Bondi's contributions group has been proposed for the DEDMS, HMCTSO, HMDSO and OMTSO polymers. This model is based on mesoscopic parameters like the density of the polymer and factor T = number of (Si–C) bonds/number of (Si–O) bonds. The model has displayed good correlations factors for the studied polymers.

Platinum is deposited into porous carbon materials relevant for fuel cell electrodes using plasma sputtering techniques. The resulting platinum concentration profile extends up to 2 µm into the porous carbon and is well fitted by a generalized stretched Gaussian function, which displays the non-thermal nature of the penetration process. Platinum deposits are observed to grow as clusters. On the outermost carbon particles, platinum nano-cluster sizes of 3.5 nm have been measured. In tests using actual PEM fuel cells, current densities as high as 1000 mA cm−2 have been obtained at 400 mV with 25 cm2 plasma electrodes. This compares favourably with commercially available electrodes but the present electrodes have a platinum density 4.5 times lower and hence can be considered to be significantly more efficient.

The experimental design method was used to investigate the PECVD parameters effects on the properties of plasma polysiloxane membranes synthesized using octamethylcyclotetrasiloxane or hexamethyldisiloxane as monomers. On a wide experimental range and with a minimum number of experiments, the use of such a statistical tool enabled us to set up complete and reliable correlations, in the form of polynomial models connecting the gas transport properties (H2 permeability coefficient, H2/N2 ideal selectivity) and the structural properties (growth rate, density, organic/inorganic nature) of synthesized films with the two most influent synthesis parameters of the PECVD process: the input power (represented by the input voltage) and the monomer flux. The polynomial models enabled us not only to statistically confirm the effects of the PECVD parameters displayed by previous classical experimental studies, but also to model, in the mathematical sense, the evolution of each property of materials taking into account the first and second orders effects of both PECVD synthesis parameters. By the use of a performing statistical tool, we managed to improve the knowledge of relations between synthesis parameters/structure/properties relative to our process.

International audience; Thin a-SiOxCyHz film membranes were deposited from hexamethyldisiloxane precursor on ester of cellulose porous substrates at low-frequency plasma conditions. The sorption properties of the films were measured for CH4, C2H6, C3H8, n-C4H10 and i-C4H10 by using a gravimetric method with a quartz microbalance. The gas permeability coefficients were determined by using the constant-volume pressure-increase method. Correlations were established between the physical parameters of the penetrants and the corresponding sorption, permeation and diffusion coefficients observed. (C) 2003 Elsevier Science B.V. All rights reserved.

Grafting of aminosiloxane groups on PVDF supports was performed in a low-frequency plasma deposition process using a tetramethylsilane/ammoniac mixture. The morphology and thickness of plasma-grafted PVDF membranes were characterized by SEM observations; their chemical structure was determined by FTIR analysis, XPS analysis, and contact angle measurements. The membranes anion-exchange capacity for the transport of Cr(VI) was investigated by electroelectrodialysis using a three compartments Kel'F cell. We are able to correlate the plasma grafting parameters with the structure and the electrotransport performances of the synthesized membranes. Starting from 0.10 for the virgin PVDF films, the best Cr(VI) transport number (0.155) is obtained for membranes both rich in substituted amine functions and hydrophobic enough synthesized from an equimolar tetramethylsilane/ammoniac plasma monomers mixture.

In the highly competitive market of fuel cells, proton exchange membrane fuel cells operating in the range of 80–150 °C seem quite promising. One of the main hurdles for the emergence of such a technology is the development of phosphonic acid-based membranes characterized by high conductivity and stability beyond 80 °C. In this work, plasma polymers containing phosphonic acid groups have been successfully prepared using dimethyl allylphosphonate as a single precursor. Structural and transport properties of plasma polymers are logically correlated with the plasma discharge power. Under optimized plasma conditions, plasma films are thermally stable up to 150 °C and present the highest growth rate, concentration of ion exchange groups and proton conductivity, which make them competitive as membranes for fuel cells.

Thin a-SiO x C y H z membranes were deposited from two different organosilicon precursors, a linear one the octamethyltrisiloxane (MDM) and a cyclic one the hexamethylcyclotrisiloxane (D3), in a low-frequency plasma polymerization process. The chemical structure of polysiloxane plasma materials was characterized using two different spectroscopic analyses: the X-ray Photoelectron Spectroscopy (XPS) and the 29 Si solid-state Nuclear Magnetic Resonance (NMR). Both techniques show that it is possible to synthesize a wide range of materials, more or less organic and close to silicone-type conventional polymers, depending on whether the energetic character of the plasma is low or high. The structural differences between plasma films synthesized from MDM (PP-MDM films) and plasma materials deposited from D3 (PP-D3 films) are all the more pronounced that the plasma conditions are soft due to the better preservation of the monomer chemical structure. The NMR analysis allows to display the presence of cyclic siloxane chains in PP-D3 layers whereas PP-MDM materials are exclusively composed of linear siloxane chains.

The structure of thin films prepared from O2/TEOS plasmas in an rf helicon reactor has been investigated using in situ UV-visible spectroscopic ellipsometry and ex situ X-ray, reflectivity, Fourier transform infrared, photoelectron and Rutherford backscattering spectroscopy. It is shown how the structure of the films evolves from an inorganic silica-like structure towards an organic SiOxCyHz framework when the relative proportion of TEOS in the plasma increases. On the one hand, the structure and properties of the silica-like films are shown to be very close to those of a thermal oxide. On the other hand, the organic films have larger refractive index and extinction coeAcient but are less dense than the SiO2-like films. It is shown that the increase in the refractive index and extinction coeAcient is correlated to the carbon incorporation into the film. It is further established that the O/Si content ratio is enhanced from about 2 to 2.5 with increasing TEOS volume fraction. This evolution is explained by the increasing number of Si‐O‐H and Si‐O‐CxHy bonds in the material at the cost of the number of ‐Si‐O‐Si‐ bonds. It is furthermore shown that the abrupt character of the transition between silica-like and organic films is likely to be correlated to the depletion in oxygen atoms in the plasma. ” 2000 Elsevier Science B.V. All rights reserved.

Thin a-SiO x C y H z films were deposited from different cyclic and linear organosilicon precursors in a radio-frequency plasma polymerization process. The plasma deposition and the film properties were characterized with respect to the deposition rate, the layers density and the chemical structure determined by FTIR and 29 Si NMR analysis. The qualification of the films for gas-selective membranes was tested on ester of cellulose substrates using N 2 , H 2 , O 2 , CO 2 and CH 4 . We are able to correlate both physico-chemical properties and permeation performances of the synthesized polymers with the composite parameter V/F.M (V: input voltage. F: monomer flow rate. M: monomer molecular weight) which describes the energetic character of the plasma. At low V/F.M ratios, the thin layers extremely preserve the monomeric structure and get close to polydimethylsiloxane; this resemblance is all the more considerable that the precursor siloxane chain is longer, and particularly pronounced using cyclic monomers. As V/F.M increases, the plasma polymers have a more inorganic structure and higher density: the materials tend towards a silica-like structure. Concurrently, the synthesized membranes exhibit solution-diffusion controlled or Knudsen-like separation factors depending on whether plasma conditions are soft (low V/F.M ratios) or drastic (high V/F.M ratios).

Thin silicon films were made by low pressure chemical vapour deposition from pure silane (SiH 4 ) on a Si/SiO 2 substrate. They have been studied by X-ray Reflectivity, Atomic Force Microscopy, and Scanning Electron Microscopy, as a function of deposition time. It was observed that the growth starts by the formation of a layer that only partially covers the substrate (thickness < 5 nm). This layer subsequently fully covers the substrate leading to a smooth film that is initially partially covered by a large number of nuclei (height 10 nm, density 120 per square micron). With increasing layer thickness the nuclei density diminishes, the nuclei width increases, and their height becomes smaller. It is suggested that small proportions of the very active radical SiH 2 , which is present in the gas phase, play a central role in the first stages of growth. The possibility to obtain complementary information on the surface morphology from X-ray reflectivity and atomic force microscopy data is discussed.

Thin a-SiOxCyHz films were deposited from diethoxydimethylsilane in a radio-frequency plasma polymerization process. The plasma deposition and the film properties were characterized with respect to the deposition rate evaluated from scanning electron microscopy observations, the film refractive index determined by spectroscopic ellipsometry and the film density measured by X-ray reflectometry. The layer chemical structure was investigated by Fourier-transform infrared spectroscopy analysis, 29Si solid-state nuclear magnetic resonance technique, and X-ray photoelectron spectroscopy measurements. The film growth rate exhibits a typical evolution as a function of the process parameters and appears to be dependent on the nature of the substrate. We are able to correlate the structure of the films obtained with the important composite parameter V/Pp (RF voltage V over the monomer partial pressure Pp) characterizing the input energy per unit mass of monomer. Chemical analysis spectra show that the concentration of [(CH3)2–Si(–O)2] silicon environment increases with lowering the V/Pp ratio; at very low V/Pp values, plasma polymers are close to polydimethylsiloxane. By contrast, the thin layers contain a high [SiO4] concentration, characteristic of SiO2, when V/Pp increases. Moreover, increasing V/Pp results in higher C/Si and O/Si ratios while the film's density and refractive index also rise.

Summary During this work, a new ultrafiltration membrane based on potassium titanyl phosphate has been prepared. Pore diameters are equal to 10 nm and the permeability is close to 20 l/m 2 h bar. The rejection of neutral molecules and ions was determined in relation to the charge of the membrane.

We constructed silicon oxynitride thin films of various compositions by Plasma Enhanced Chemical Vapor Deposition and studied the global structure by infrared absorption. The Si-H band frequency is related to the environment of Si atom. We considered the Si-H band as the sum of several gaussian curves corresponding to the different silicon-centered tetraedra present in the material. The frequency of Si-H bond for each tetrahedron was calculated using Lucovsky linear relations and then the tetrahedra were attributed to gaussians found by decomposition of the band. The results show the presence of tetrahedra with both N and O atoms bound to silicon. These tetrahedra cannot agree with a model of phase separation, however the Random Bonding Model envisages the existence of these environments. So we consider our silicon oxynitride films to be a homogeneous statistical mixture of the various bonds rather than a mixture of phases.

SiO x N y thin films have been prepared by the Plasma Enhanced Chemical Vapour Deposition (PECVD). From the information acquired by XPS for the composition, ellipsometry for the refractive index and grazing X-rays reflectometry for the density, it is possible to establish a relation between these three characteristics of the layer from the Bruggeman and Clausius-Mossoti equations. Published by Elsevier Science Limited.

International audience; The uptake and release capacities of mesoporous silica particles are measured on nanovalve-gated stimulated release systems, using a water soluble biological stain, Hoechst 33342, as the cargo model. Five different types of mesoporous silica nanoparticles: 2D-hexagonal MCM-41, swollen pore MCM-41, rod-like MCM-41, hollow mesoporous nanoparticles and radial mesoporous nanoparticles are studied and compared. Solid silica nanoparticles are used as the control. Because of the presence of the nanovalves, the loaded and capped particles can be washed thoroughly without losing the content of the mesopores. The quantity of Hoechst 33342 molecules trapped within the nanoparticles and released upon opening the nanovalves are systematically studied for the first time. The loading conditions are optimized by varying the Hoechst concentration in the loading solutions. Surprisingly, increasing the Hoechst concentration in the loading solution does not always result in a larger amount of Hoechst being trapped and released. Among the five types of mesoporous silica nanoparticles, the radial mesoporous nanoparticles and the swollen pore MCM-41 particles show the highest and lowest release capacity, respectively. The uptake capacities is correlated with the specific surface area of the materials rather than their internal volume. The uptake and release behaviors are also affected by charge and spatial factors.

Comparison of the X-ray photoelectron spectroscopy (XPS) spectra for surfaces of Parylene C thin layers deposited on alumina substrates without heating or after various heating times at 150 °C revealed an increase in chlorine concentration near the surface with increasing heating time. After 200 h heating at 150 °C, the Parylene C layer flaked off of the alumina substrate. The deterioration of the Parylene C seemed to be related to a chlorine transfer from the bulk of the layer to the free surface. A SiN x :H thin film was deposited on the Parylene C layer and characterized by XPS measurements. An Auger study of the SiN x :H film/Parylene C interface also revealed a chlorine excess in the interfacial region induced by heating the SiN x :H-Parylene C multilayer. However, after 200 h heating of the SiN x :H-coated Parylene C, the polymer appeared to be much less deteriorated than the uncoated film. This better stability of the coated Parylene C polymer seems to be the result of a decrease of the chlorine loss caused by the presence of the SiN x :H barrier.

In the field of low-temperature fuel cells, solid alkaline membrane fuel cells (SAMFCs) appear to be a very promising new fuel cell technology. Nevertheless, commercial hydroxyl-exchange membranes suitable for SAMFCs suffer from some limitations, especially low retention to water at the cathode (where water is required to be reactive in the electrochemical reaction), which weakens fuel cell performances. In this study, the commercial Morgan ADP membrane by Solvay has been modified on the surface by plasma processes using argon or argon/triallylamine as gaseous phases. Plasma-treated and untreated membranes have been characterized in terms of water sorption and diffusion properties performing water vapor sorption measurements. Analysis of sorption isotherms and related modeling from Park model has shown that plasma treatments induce a decrease in water sorption and diffusion abilities without qualitatively affecting the water transport properties. Plasma modification from triallylamine leading to the depos...

Le procede sol-gel de destabilisation d'une solution colloidale a ete employe pour preparer les phosphate (KTP) et arseniate (KTA) de potassium et de titanyle. Ces materiaux piezoelectriques ont ete caracterises par analyse thermique, diffraction des rayons X, spectroscopie d'absorption infrarouge et generation de seconde harmonique (GSH). KTP et KTA cristallisent entre 500 et 600 o C, et se decomposent entre 1150 et 1200 o C. Le rendement du signal du GSH de KTA est 1,65 fois celui du KTP

International audience; Plasma polymerization of styrene is widely used to synthesize polymer membranes for various applications. Under certain specific conditions, it is possible to grow polystyrene nanoballs. In this paper, we highlight the potential of plasma polymerization to synthesize polystyrene balls.

AES, XPS and IR studies of silicon-carbon alloys (a-Si x C 1- x :H), obtained by PECVD (plasma-enhanced chemical vapor) deposition), on polypropylene reveal a Si-concentration gradient in the coating thickness whichever the gaseous composition used for the deposition. Furthermore, an adhesion zone between the isotactic polypropylene and the thin film is pointed out. Structural characterizations of this coating on isotactic polypropylene allow the formation mechanisms to be determined.

Multilayer structures metal-insulator-metal are deposited on tungsten wires in view to realize capacitive systems. Both metal and insulator layers are formed in the same reactor by a glow discharge gas phase decomposition under a frequency of 35 kHz and a temperature of 375 °C. The materials chosen are tungsten and silicon nitride. Tungsten silicide is deposited as an interphase layer for the lack of adhesion of tungsten to silicon nitride. X-ray diffraction, AES and XPS studies show that tungsten films consists of pure phase α with no evidence for incorporation of oxygen. Resistivity measurements on tungsten films exhibit a bulk material resistivity of 20 μΩ cm. The adhesion layer consists of WSi 2 material with hexagonal crystalline structure having a resistivity of 560 μΩ cm. Silicon nitride is a near stoichiometric material as deduced from AES spectra. Capacitance values versus insulator thickness were measured on cylindrical structures and showed a good fit between results and theory.

Based on the experimental results of deposition of AIN thin films by using plasma-enhanced metalorganic chemical vapour deposition (PEMOCVD) with TMA1 and NH 3 as reactants and different glow dischange frequencies (35 kHz, 110 kHz, 440 kHz and 13.56 MHz), a surface kinetic growth model was proposed to describe the deposition process mechanisms. The (10 1 0) oriented growth of AlN thin films in low frequency plasma systems as well as other experimental results both from this work and from the literature can be well explained by the model associated with additional consideration of the effect of plasma excitation and bombardment of energetic ions on the growing surface. It is supposed to be valid in other similar chemical vapour deposition (CVD) systems.

Le dépôt chimique en phase vapeur d'organo-métalliques assisté d'un plasma réactif conduit à des revêtements cristallins de nitrure d'aluminium ayant une orientation préférentielle (10$\bar{1}$0) marquée. La dimension des cristallites dépend de la fréquence d'excitation plasma et est indépendante de la nature du substrat. Les revêtements, caractérisés par diffraction des rayons X, spectroscopies infrarouge et des électrons Auger, montrent une composition AlN. L'interphase AIN/Si a fait l'objet d'une étude particulière par microscopie électronique à transmission.

Amorphous a-Si x C 1− x :H films have been prepared by low-temperature, low-frequency PECVD. Information on the microstructure was obtained from a fine study of the shape of the SiLVV, SiKLL and CKVV peaks. Correlated with our previous IR, XPS and EXAFS studies, the results reveal the existence of three domains as a function of composition x , corresponding to three different types of materials. Structural models are proposed for each of them.

Ceramic coatings are deposited by the PECVD technique. The required mechanical, electrical, optical, adherence on the substrate, surface (wettability) features are achieved owing to the construction of multilayers with steep interfaces or interphases with gradients of composition. A wide variety of applications are given

The growth morphology of berlinite (AlPO 4 ) crystals obtained under hydrothermal conditions depends on the solvent employed (H 3 PO 4 , HCl, H 2 SO 4 , and their mixtures) and the crystallization temperature. We have constructed a morphological diagram (morphogram) showing the resulting habits by changing the relative growth rates of the r (1011) and π (1012) faces with respect to the m (1010) face, and keeping the ratios between the growth rates of the first two types of faces and the growth rates of the z (0111) and π'(0112) constant and equal to 0.9. This allows us to compare these polyhedra with those obtained in the growth runs

Plasma processes, initially developed for micro-electronics in the fifties, represent a clean and very flexible technology which has been used in many fields of the materials chemistry since the eighties. The potentialities of plasma processes in modifying or depositing thin layers on materials surface are exceptionally broad, hence their increasing interest for membrane applications. Depending on the nature of the gas used to create the plasma phase, plasma processes are likely to provide grafting, etching, cross-linking and/or deposition of a thin film on the surface of various materials with a high degree of flexibility leading to the manufacture of innovating membranes. Reviewing the most striking research works dealing with plasma membranes and pointing out the specificities of these membranes in term of structural and transport properties in comparison with more conventional membranes are the main objectives of the following text

Plasma processes, initially developed for microelectronics in the 1950s, represent a clean and very flexible technology which has been used in many fields of materials chemistry since the 1980s. The potentialities of plasma processes in modifying or depositing thin layers on materials surface are exceptionally broad; hence the increasing interest in them for membrane applications. Depending on the nature of the gas used to create the plasma phase, plasma processes are likely to provide grafting, etching, crosslinking, and/or deposition of a thin film on the surface of various materials with a high degree of flexibility leading to the manufacture of innovating membranes. Reviewing the most striking research works dealing with plasma membranes and pointing out the specificities of these membranes in terms of structural and transport properties in comparison with more conventional membranes are the main objectives of this chapter.

Hydrogenated amorphous a-SiNx: H films were prepared using a 35 kHz low-frequency glow discharge decomposition of silane and ammonia gas mixture without thermal activation. Samples with different silicon contents were studied by AES and FTIR. Silicon LVV and KLL peak profiles were analyzed as functions of the silicon content of the layer. The structure of the silicon-rich films was found to be highly disordered with several kinds of tetrahedron around the silicon atoms. The structure of the nitrogen-rich films appears more ordered and consists mainly of SiN bonds and can be described as a modification of the c-Si3N4 structure in which SiN bonds are replaced by SiH bonds.

The surface properties of air-exposed plasma-deposited hydrogenated amorphous silicon carbide films were studied by the tensiometric method. The low wettability has been attributed to CHn groups, giving a polymer-like character to the material, which increases with the carbon content of the layer. Composition and structure of the surface were studied by Auger electron spectroscopy which reveals the presence of carbon, oxygen and hydrogen in the environment of silicon atoms.

The local atomic structure around silicon has been studied from EXAFS spectra at Si K edge in both PECVD and triode sputtered a-Si x C 1-x (H) films. Si-C and Si-Si bonds are observed in a ratio depending of the composition for the two first atomic shells. After annealing at 750°C no clusters are present in the amorphous.

Thin films of phosphorus nitride have been deposited on InP at 270°C by the PECVD method using phosphorus trichloride and ammonia diluted in hydrogen. Observation by scanning electron microscopy shows a compact, homogeneous and smooth film with a well-defined interface. The films have been characterized by infrared and optical absorption. The optical band gap values for the best films are 5.5 and 5.7 eV before and after annealing in a 5% H 2 and 95% N 2 atmosphere. Two typical samples have been studied by Auger spectroscopy measurements. The spectra scanned after Ar + sputter etching show good homogeneity of the phosphorus nitride film bulk. The presence of chlorine in the interface layer was particularly evidenced in the case of interface oxidization. The bulk composition evaluated using the peak to background ratios allowed us to conclude that the film has a composition near P 3 N 5 .

Hydrogenated amorphous SixC1−x:H films with various compositions were prepared by low frequency (110 kHz) glow discharge decomposition of a silane and methane mixture diluted by helium. The deposition rate, the composition, the structure and the refractive index of the films were studied using SEM, AES and IB analyses. Only the deposition rate was found to be influenced by the position of the silicon substrate in the reactor. From infrared analyses we estimate that the structure of the films is a tetrahedral network where carbon atoms are randomly replaced by silicon atoms and where only one single hydrogen is bound to silicon. The rather dense and inorganic character of these films is confirmed by the high values of their refractive index ranging from 2.1 for x=0 to 3.4 for x=1.

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