This research was designed to fabricate and characterize novel polyhedral phase segregated microstructures of polystyrene (PS)-matrix composites filled with multi-walled carbon nanotubes (MWNT) and indium tin oxide (ITO) nanopowders. PS-composites were compression molded with MWNT and ITO separately first. The resulting composites were conducting, and remained optically transparent. Mixtures of MWNT and ITO were then used to form mixed ITO/MWNT PS-composites in order to optimize their transparency and conductivity. This was achieved by fabricating composites with varying concentrations of fillers. Impedance spectroscopy was used to characterize the electrical properties of the PS-composites. Optical properties were characterized by measuring the transmission of light through the PS-composite in the visible light spectrum using a spectrophotometer. The electrical properties and microstructural attributes of the fillers used were also characterized. The main objective of the project was to understand the relationships between the structural, electrical, and optical properties of the PS-composites. The resistivity of PS-composites filled with MWNT ranged from 105 to 1013 Ω cm for samples with 0.007 to 0.9 vol% MWNT. The resistivity of PS-composites filled with ITO ranged from 107 to 1013 Ω cm for PS-composites with 0.034 to 0.86 vol% ITO. PS/ITO composites had a percolation threshold of 0.15, 0.25, or 0.3 phr ITO, depending on the type of ITO used in the composite. The percolation threshold of PS/MWNT composites was found to be 0.01 phr MWNT. Mixed ITO/MWNT PS-composites were already percolated, the concentrations investigated in xv ii this study were already above the percolation threshold of these composites. A time dependence on impedance was found for PS-composites filled with MWNT. As time increases there is a decrease in impedance, and in some cases also a dependence on voltage. All PS-composites showed a dependence on the microstructure of the PS matrix and the filler material. The resistivity and percolation threshold were lower for PS/MWNT composites than PS/ITO composites due to the difference in filler size and aspect ratio, since MWNT have a smaller size. The orientation of PS grains with respect to neighboring grains was found to affect the resistivity of PS/MWNT. PS/MWNT composites with preferentially oriented PS grains were found to have a lower resistivity. Mixed ITO/MWNT PS-composites with the right filler concentrations were able to maintain transmission while decreasing resistivity. The fracture surface of fractured PS-composites prepared in this work indicated that there was bonding between adjacent PS-grains. From this work, it can be concluded that large grain hybrid ITO/MWNT PS-composites provide insight into the effect of combining nanometer sized filler materials together in a polymer matrix on the resultant structural, electrical, and optical properties of the composite. In the future, it is recommended that this study be used to aid research in flexible transparent conducting electrodes using a polymer matrix and hybrid/mixed nanometer sized conducting fillers.

Les applications présentées dans cette thèse valorisent de diverses manières le principe d'ablation laser, c'est à dire l'arrachement de la matière d'une surface solide suite à l'irradiation avec un faisceau laser. Le plasma généré par irradiation laser impulsionnel a été utilisé pour le dépôt de couches minces ou de nanoparticules et pour l'analyse compositionnelle des couches d'épaisseur nanométrique. Nous avons synthétisé par dépôt laser combinatoire des librairies compositionnelles d'un oxyde mixte transparent d'In et Zn. En utilisant le plasma d'ablation pour le diagnostic compositionnel, nous avons déterminé les concentrations d'indium et de zinc dans les couches minces par spectroscopie laser. Des couches minces de bioverre ont été synthétisées par dépôt laser impulsionnel sur des substrats de titane. En contact avec des cellules ostéoblastes, les bioverres ont stimulé la prolifération et ont augmenté la viabilité. La prolifération des ostéoblastes cultivés sur les couches de bioverre a été 30% supérieure a l'échantillon de contrôle. On a déposé par PLD des couches minces ou nanoparticules adhérentes de ZnO sur des substrats textiles hydrophiles dans un flux d'oxygène ou sous vide pour obtenir des structures avec différentes mouillabilités. En augmentant le nombre d'impulsions laser de 10 à 100 nous avons observé la transition du recouvrement par des nanoparticules isolées vers des couches minces. En fonction de l'atmosphère environnant lors du dépôt, les couches minces et les nanoparticules ont changé leur mouillabilité, passant d'hydrophile en flux d'oxygène à un comportement superhydrophobe (angle de contact de 157°) en cas de dépôt sous vide. / The applications presented in this thesis exploit in different modes the principle of laser ablation, i.e. the material removal from a solid surface following irradiation with a pulsed laser beam. The plasma generated by laser ablation was used for thin films or nanoparticles deposition and for the compositional analysis of nanometric thin films. We synthesized by combinatorial pulsed laser deposition, thin film libraries of a complex oxide of In and Zn. Using the ablation plasma for compositional diagnostic, we determined the In and Zn concentrations in films by Laser Induced Breakdown Spectroscopy using a procedure based on the spectral luminance calculation of a plasma in local thermodynamic equilibrium. Thin films of bioactive glass were synthesized by pulsed laser deposition, magnetron sputtering and MAPLE on Ti substrates and tested the transfer accuracy by physico-chemical tests and their functionality in vitro. In contact with human osteoblast cells, the bioactive glasses stimulated their proliferation and enhanced their viability. The proliferation of osteoblasts cultivated on bioactive films was 30% superior to the control sample. ZnO thin films or nanoparticles were deposited on hydrophilic textile substrates in oxygen flux or in vacuum in order to obtain structures with different wetting behavior. Increasing the number of laser pulses from 10 to 100, we observed a coating transition from isolated nanoparticles to thin films fully coating the textile fibers. Function of the ambient atmosphere during experiments, the structures changed their wetting behavior, passing from hydrophilic in oxygen flux to superhydrophobic (157°) in case of deposition in vacuum.