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Conductive polymer composite sensors have shown great potential in identifying gaseous analytes. To more thoroughly understand the physical and chemical mechanism of this type of sensors, a model was developed by combining two sub-models: a conductivity model and a thermodynamic model, which gives a relationship between the vapor concentration of analyte(s) and the change of the sensor signals. In this work, 64 chemiresistors representing eight different carbon concentrations (8–60 vol.% carbon) were constructed by depositing thin films of a carbon black–polyisobutylene composite onto concentric spiral platinum electrodes on a silicon chip. The responses of the sensors were measured in dry air and at various vapor pressures of toluene and trichloroethylene. Three parameters in the conductivity model were determined by fitting the experimental data. It was shown that by applying this model, the sensor responses can be predicted if the vapor pressure is known; furthermore the vapor concentration can be estimated based on the sensor responses. This model will guide the improvement of the design and fabrication of conductive polymer composite sensors for detecting and identifying organic vapors. A novel method was developed to optimize the selection of polymeric materials to be used within a chemiresistor array for anticipated samples without performing preliminary experiments. It is based on the theoretical predicted responses of chemiresistors and the criterion of minimizing the mean square error (MSE) of the chemiresistor array. After the number of chemiresistors to be used in an array and the anticipated sample chemistry are determined, the MSE values of all combinations of the candidate chemiresistors are calculated. The combination which has the minimum MSE value is the best choice. This can become computationally intensive for selection of polymers for large arrays from candidates in a large database. The number of combinations can be reduced by using the branch and bound method to save computation time. This method is suitable for samples at low concentrations where thermodynamic multi-component interactions are linear. To help users apply this polymer selection method for the sensors, a website including 10 solvents and 10 polymers was developed. Users can specify a target sample and obtain the best set of polymers for a sensor array to detect the sample. The activities of trichloroethylene and toluene in polyisobutylene were measured at very low concentrations. The activities for toluene are consistent with published values at higher concentrations. The values for trichloroethylene are a new contribution to the literature.

Cette thèse a pour but de contribuer à la mise au point et le développement, de plaques mono ou bipolaires composites pour piles à combustibles à membranes échangeuses de protons (ou PEMFC). Les plaques mono ou bipolaires (selon le type de refroidissement choisi) sont un élément essentiel au fonctionnement des piles car elles l’alimentent en gaz réactifs (hydrogène et oxygène de l’air), assurent la tenue mécanique des cellules, la séparation des compartiments anodique et cathodique, le collectage des électrons, et l’évacuation des « sous-produits » eau et chaleur. L’optimisation des propriétés physico-chimiques et mécaniques des plaques, et de leur procédé d’élaboration, permettra de rendre de ce fait la technologie pile à combustible plus accessible Après une étude bibliographique centrée sur les systèmes composites à taux de charges ou de renforts élevé et leurs propriétés physicochimiques, mécaniques et électriques, la 2ème phase sera axée sur une contribution à l’optimisation des formulations par des analyses morphologiques, physiques et physicochimiques pertinentes. La 3ème phase sera dédiée à l’analyse des plaques mono ou bipolaires après tests en piles afin de permettre des choix entre les différentes formulations ou procédés de mise en œuvre des plaques mono et bipolaires et dégager des paramètres pertinents reliés aux propriétés d’usage et à leur évolution au cours du temps en conditions réelles d’utilisation. / The objective of this work is to design carbon polymer composites for bipolar plates, with high and homogeneous electrical and mechanical properties. A method was designed in order to analyze the electrical conductivity homogeneity of the bipolar plates. Several designs of experiments were formulated after optimization of the most influencing formulation parameters on the use properties. This first step enhanced the use properties of the resulting materials, though insufficiently. The plates characterization showed highly heterogeneous and anisotropic use properties. The fabrication process conditions optimization (thermosets formulations) and the addition of an annealing step (thermoplastic formulations) then improved significantly the use properties and their homogeneity.