Thermal oxidative stability of polyanilines

This paper deals with thermal ageing of polyaniline obtained from plasma or chemical ways. FTIR analyses suggest the formation of stable carbonyl compounds in both cases. The plasma polyaniline degrades clearly faster than its chemical analog which is discussed from structural considerations. The consequences of thermal ageing on the surface properties monitored by Water Contact Angles (WCA) are also considered and explained as the overlap of an “oxidation” component that decreases WCA and a “crosslinking” component (only observed in plasma polyaniline) responsible for the WCA increase

Copolymérisation plasma (étude des mécanismes de croissance et de la structuration des couches minces copolymères)

Le travail présenté dans ce mémoire consiste à élaborer en une seule étape une couche mince organique ayant les propriétés chimiques et/ou morphologiques souhaitées. Cette démarche vise à copolymériser par voie plasma (PECVD) deux monomères antagonistes (apolaire et polaire) afin de contrôler la répartition et la taille des nodules de l un des polymères dispersé dans l autre phase et d obtenir ainsi une structuration chimique et/ou morphologique. Pour ce faire, six précurseurs ont été sélectionnés de façon à couvrir une large gamme de polarité: l alcool allylique (AA), l acide acrylique (AAc), l aniline (ANi), le diéthylèneglycol diméthyl éther (DEGDME), le 1H,1H,2H-perfluoro-1-décène (HDFD) et le 2-(diméthylamino) éthyle méthacrylate (DMAEMA).La première partie de ce travail est centrée sur l étude des mécanismes de croissance des différents homopolymères par voie plasma pulsé. Les cinétiques de dépôt, les structures chimiques et les morphologies sont plus spécifiquement détaillées pour deux monomères, les HDFD et DMAEMA en fonction des paramètres du procédé plasma, la polymérisation plasma de ces deux précurseurs étant pour la première fois décrite. La caractérisation des couches minces obtenues repose sur la spectroscopie Infrarouge à Transformée de Fourier (FTIR), la spectroscopie de photoélectrons X (XPS) et la microscopie à force atomique (AFM). Cette étude a montré le rôle catalytique des groupements fluorés induisant des vitesses de dépôt plus conséquentes. Même si la croissance est prépondérante durant le temps de décharge, le dépôt est non négligeable pendant la post-décharge. La structure chimique des polymères plasma est fortement dépendante des paramètres de la décharge et notamment la puissance et le temps de décharge. La spectroscopie FTIR s est révélée comme un outil performant pour l évaluation de la rétention de la structure chimique de l entité monomère initiale dans le polymère plasma. Ces homopolymères présentent une morphologie homogène sans rugosité.Dans la deuxième partie, nous abordons la copolymérisation plasma pulsé. Les différents copolymères synthétisés sont p-AA-co-HDFD, p-AAc-co-HDFD, p-ANi-co-HDFD, p-DEGDME-co-HDFD, p-DMAEMA-co-HDFD, p-DMAEMA-co-ANi. La plupart sont issus de comonomères hydrophiles et hydrophobes à l exception d un synthétisé à partir de deux précurseurs polaires. Les cinétiques de dépôt, les propriétés chimiques et morphologiques sont discutées en fonction des paramètres plasma tels que la puissance injectée mais aussi des proportions relatives des différents comonomères. Les différentes analyses chimiques entreprises montrent plutôt la formation d un mélange d homopolymères ou d un copolymère à bloc plutôt que la croissance d un nouveau matériau. Cette hypothèse est étayée par la mise en évidence d une structuration morphologique correspondant à la présence d îlots à la surface.The work presented in this thesis consists to elaborate only in one step a thin organic layer having the required chemical and/or morphological properties. This approach aims to plasma copolymerize (PECVD) two antagonistic monomers (nonpolar and polar) in order of controlling the repartition and the size of nodules of one of the polymers dispersed in the other phase and thus, of inducting a chemical and/or morphological structuring. For this, six precursors have been selected to cover a large range of polarity: allyl alcohol (AA), acrylic acid (AAc), aniline (ANi), the diethylene glycol dimethyl ether (DEGDME), the 1H,1H,2H-perfluor-1-decene (HDFD) and 2-(dimethylamino)ethyl methacrylate (DMAEMA).The first part of this work is centered on studying the growth mechanism of different homo-polymers through pulsed plasma. The kinetics of deposition, the chemical structures and morphologies are more specifically detailed for two monomers, HDFD and DMAEMA in function of plasma parameters, the plasma polymerization of these two precursors being described for the first time. The thin layers were characterized through Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). This study showed the catalytic role of fluorine groups inducing more consequent deposit rates. Even if the growth is significant during the plasma on-time, the deposit is not negligible during the plasma off-time. The chemical structure of plasma polymers is highly dependent on the discharge parameters and mainly the power and the pulse period. The FTIR spectroscopy was shown to be a relevant tool for evaluating the chemical structure s retention of the initial monomer entity in the plasma polymer. These homopolymers present a homogenous morphology without roughness.In the second part, the pulsed plasma copolymerization is described. The different synthesized copolymers are p-AA-co-HDFD, p-AAc-co-HDFD, p-ANi-co-HDFD, p-DEGDME-co-HDFD, p-DMAEMA-co-HDFD, p-DMAEMA-co-ANi. The majorities are issued from hydrophilic and hydrophobic co-monomers excepted for one synthesized from two polar precursors. The kinetics of deposits, the chemical and morphological properties were discussed in function to plasma parameters such as the injected power as well as the relative proportions of different co-monomers. The different chemical analyses showed the formation of a mixture of homopolymers or of a block copolymer rather than the growth of a new material. This hypothesis is unsubstantiated by evidencing a morphological structuring corresponding to the presence of spherical nanostructure at the surface.LE MANS-BU Sciences (721812109) / SudocSudocFranceF

Amélioration du dosage des protéines neurodégénératives par un contrôle des propriétés de surface du puits de dosage

Nombreuses sont aujourd hui les maladies neurodégénératives (Creutzfelt-Jacob, Parkinson, Alzheimer, Lewis), c est-à-dire touchant le système nerveux, dont la cause et la détection restent des sujets de recherches actuels. Ces maladies se traduisent par l apparition, entre autre dans le système sanguin et nerveux, d une protéine antigénique spécifique à chaque affection. Bien que les symptômes permettent leur détection, seule l autopsie donne lieu à un diagnostic de certitude. En effet, la concentration de l agent pathogène étant en quantité maximale lors du décès, la confirmation de la maladie n est exacte que par analyses post-mortem. A l heure actuelle, le dosage de l antigène est réalisé à l aide d une méthode de détection immunoeznymologique appelée ELISA (Enzyme Linked ImmunoSorbent Assays). Malgré son efficacité reconnue, cette méthode ne possède pas une sensibilité suffisante à la détection de la protéine antigénique en faible concentration, c est-à-dire à un stade ante-mortem. Son efficacité dépend de la faculté d attachement d un anticorps primaire à la surface des supports de détection. De cette accroche dépend la capture de l antigène. Pour se faire, une idée originale est de modifier la surface du matériau d analyse sans changer ses propriétés intrinsèques. Ceci dans le but de les rendre biocompatibles et d améliorer l accroche de l anticorps de capture sur la surface en la rendant plus spécifique tout en réduisant les adsorptions aspécifiques des autres biomolécules mises en jeu et responsables d un bruit de fond parasite.LE MANS-BU Lettres (721812108) / SudocSudocFranceF

Plasma O2modifies the structure of synthetic zeolite-A to improve the removalof cadmium ions from aqueous solutions

International audienceThe present study addresses the removal of cadmium ions (Cd(II)) from aqueous solutions at a pH of 7.5 using zeolite-A activated by exposure to oxygen plasma. The activation process was performed over a wide range of plasma powers (10, 20, 30, and 40 W) and exposure times (30 to 360 s). Oxygen plasma cannot chemically modify zeolite to a considerable extent, but it can clean the surface, open blocked pores, and induce the formation of additional OH groups via exposure to humidity in ambient air. Therefore, Cd +2 ion removal is increased by approximately 10% with the plasma treatments. Infrared-attenuated total reflectance spectroscopy, X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy were applied to analyze the changes in the surface structure and properties of thesamples

Control over the surface structure of the plasma-deposited polyaniline film

Proc. num. Clé USBInternational audienceA texturing of the plasma-deposited polyaniline surface is achieved with apparition of morphological features. Critical parameters are defined and their influence is demonstrated. A control over their size and density is possible by step-variation of discharge power and process duration. Different types of surface are synthesized to demonstrate the effect of each

Study of the surface fluorination of SU-8 polymer film through RF plasma treatment and its application to passive optical waveguide

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Development of an optical ammonia sensor based on polyaniline/epoxy resin (SU-8) composite.

International audiencePolyaniline (PANI)/glycidyl ether of bisphenol A (SU-8) composite film is elaborated in order to detect ammonia gas. These composite films are characterized by ultraviolet-visible (UV-vis) spectroscopy, Fourier transformed infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The sensitivity to ammonia is measured by optical absorption changes. The ammonia sensing properties of PANI/SU-8 composite films are studied, and then are compared to pure PANI films elaborated by chemical way. Experimental results show that the PANI/SU-8 optical sensor has simultaneously a rapid response to ammonia gas and regenerates easily, that is advantageous compared to pure PANI films

New sensitive layer based on pulsed plasma-polymerized aniline for integrated optical ammonia sensor.

International audienceA new integrated optical sensor based on plasma-polyaniline sensitive layer for ammonia detection is designed and developed. The sensor is based on polyaniline elaborated by the plasma technique (Plasma Enhanced Chemical Vapor Deposition, PECVD) and deposited on a small section of a single-mode planar SU-8 waveguide. The sensing properties of the integrated optical sensor to ammonia at room temperature are presented. A significant change in the guided light output power of the sensor is observed after exposition to ammonia gas. This new ammonia sensor exhibits fast response and recovery times, good reversibility and repeatability. The metrological parameters (sensitivity, response time and recovery time) of the sensor are strongly influenced by the interaction length (length of sensing region), the type of dopant and the light polarization. The sensor has a logarithmic linear optical response within the ammonia concentration range between 92 and 4618ppm

Design and sensing properties of an integrated optical gas sensor based on a multilayer structure.

International audienceIn this paper, a new multilayer integrated optical sensor (MIOS) for ammonia detection at room temperature is proposed and characterized. The sensor is integrated on a single-mode TE0-TM0 planar polymer waveguide and based on polyaniline (PANI) sensitive material. A polymethyl methacrylate (PMMA) passive layer is deposited between the waveguide core and PANI sensitive layer in order to decrease optical losses induced by evanescent wave/sensitive material coupling. The design of this new sensor is discussed. Moreover, in order to investigate the feasibility of this sensor, the sensing properties to ammonia at room temperature are studied. A significant change is observed in the guided light output power after the sensor is exposed to ammonia gas, due to PANI absorption coefficient variation. This new ammonia sensor shows fast response and recovery times, good reversibility and repeatability. The metrological parameters (sensitivity, response time and recovery time) of the sensor are strongly influenced by the interaction length (length of sensing region) and the PANI forms (doped and dedoped). The sensor has a logarithmic linear optical response within the ammonia concentration range between 92 to 4618 ppm. These experimental results demonstrate that the MIOS structure presents a potential innovation to elaborate integrated optical sensor based on non transparent (opaque) sensitive material

A new evanescent wave ammonia sensor based on polyaniline composite.

International audienceA single-mode TE(0)-TM(0) optical planar waveguide ammonia sensor based on polyaniline/polymethyl methacrylate (PANI/PMMA) composite is designed and developed. The sensing properties of the photonic sensor to ammonia at room temperature are studied. A significant change is observed in the guided light output power of the sensor after it is exposed to ammonia gas. The metrological parameters (sensitivity, response time and recovery time) of the sensor are strongly influenced by the interaction length (length of sensing region). Compared with the conventional optical ammonia sensor based on absorption spectroscopy, the integrated optical sensor is more sensitive to ammonia