Auto-assemblage de nanocristaux d'oxalate de cuivre

The nanostrucuration of matter by self-assembly is nowadays one of the most dynamic areas in fundamental research and opens many technological perspectives. In this PhD thesis is studied the self-assembly of copper oxalate nanocrystals. This compound can be considered as a model system whose properties can be transposed to the elaboration of complex nanostructures. A bibliographical study, covering on one hand the self-assembly phenomenon at the mesoscopic scale, and on the other hand the particular case of divalent metal oxalates constitutes the first part of this work. Then, the structural characterization of copper oxalate nanocrystals and the influence of the synthesis conditions on their self-assembly lead to a model of mesocrystals built from an orientation of nanocrystals by crystal faces recognition. Finally, the morphological modifications of mesocrystals in presence of additives and the spectroscopic study of these nanostructures confirm the prpoposed model by highlighting a selective adsorption of additives on some of the nanocrystals faces.La nanostructuration de la matière parauto-assemblage est actuellement un des domaines de recherche fondamentale les plus dynamiques et ouvre de vastes perspectives technologiques. Cette thèse se propose d'étudier l'auto-assemblage de nanocristaux d'oxalate de cuivre. Ce composé peut être considéré comme système modèle dont les propriétés permettent une transposition à l'élaboration de nanostructures complexes. Une étude bibliographique portant d'une part sur le phénomène d'auto-assemblage à l'échelle mésoscopique, d'autre part sur le cas particulier des oxalates de métaux divalents constitue la première partie de ce travail. Puis, la caractérisation structurale des nanocristaux d'oxalate de cuivre et l'influence des conditions de synthèse sur leur auto-assemblage permettent d'aboutir à un modèle de mésocristaux issus d'une orientation des nanocristaux par reconnaissance de faces cristallines. Enfin, les modifications morphologiques des mésocristaux en présence d'additifs et l'étude spectroscopique de ces nanostructures confirment le modèle proposé par la mise en évidence d'une adsorption sélective des additifs sur certaines faces des nanocristaux

Nanopatterning and plasmonic properties of plasma sputtered gold on diatom frustules

Bio-silica nanostructures from diatoms (called frustules) featuring plasmonic gold nanoparticles (NPs) are elaborated using two methods based on plasma sputtering of gold. The first investigated method uses a thermal treatment to induce the thermal dewetting of a plasma sputtered gold layer on the diatom frustules. The second method first consists of coating the frustules with polyethylene glycol before sputtering gold on these frustules. For both methods, the amount of gold appears to be a key parameter regarding the final obtained layer, which can either be nanostructured by cavities or consist in individual gold NPs. For an amount of sputtered gold equivalent to form a 5 nm thick layer, both methods allow obtaining diatom frustules covered by gold NPs with a size around 20 nm and a narrow size distribution. The UV-visible characterization of the diatom frustules featuring gold NPs highlights a plasmon extinction band in agreement with individual gold NPs with a size below 25 nm

Auto-assemblage de nanocristaux d'oxalate de cuivre

La nanostructuration de la matière par auto-assemblage est actuellement un des domaines de recherche fondamentale les plus dynamiques et ouvre de vastes perspectives technologiques. Cette thèse se propose d étudier l'auto-assemblage de nanocristaux d'oxalate de cuivre. Ce composé peut être considéré comme système modèle dont les propriétés permettent une transposition à l'élaboration de nanostructures complexes. Une étude bibliographique portant d'une part sur le phénomène d'auto-assemblage à l'échelle mésoscopique, d'autre part sur le cas particulier des oxalates de métaux divalents constitue la première partie de ce travail. Puis, la caractérisation structurale des nanocristaux d'oxalate de cuivre et l'influence des conditions de synthèse sur leur auto-assemblage permettent d'aboutir à un modèle de mésocristaux issus d'une orientation des nanocristaux par reconnaissance de faces cristallines. Enfin, les modifications morphologiques des mésocristaux en présence d'additifs et l'étude spectroscopique de ces nanostructures confirment le modèle proposé par la mise en évidence d'une adsorption sélective des additifs sur certaines faces des nanocristaux.The nanostrucuration of matter by self-assembly is nowadays one of the most dynamic areas in fundamental research and opens many technological perspectives. In this PhD thesis is studied the self-assembly of copper oxalate nanocrystals. This compound can be considered as a model system whose properties can be transposed to the elaboration of complex nanostructures. A bibliographical study, covering on one hand the self-assembly phenomenon at the mesoscopic scale, and on the other hand the particular case of divalent metal oxalates constitutes the first part of this work. Then, the structural characterization of copper oxalate nanocrystals and the influence of the synthesis conditions on their self-assembly lead to a model of mesocrystals built from an orientation of nanocrystals by crystal faces recognition. Finally, the morphological modifications of mesocrystals in presence of additives and the spectroscopic study of these nanostructures confirm the prpoposed model by highlighting a selective adsorption of additives on some of the nanocrystals faces.TOULON-BU Centrale (830622101) / SudocSudocFranceF

Surface Interactions between Molecules and Nanocrystals in Copper Oxalate Nanostructures

International audienc

Self-Organized Assembly of Copper Oxalate Nanocrystals

International audienc

Analyser les inégalités, entre pratiques et vécus des lycéen.ne.s. Regards croisés Montpellier / Marseille

International audienc

Computational Matching of Surface Plasmon Resonance: Interactions between Silver Nanoparticles and Ligands

A multilayer model of a single coated nanoparticle has been refined through finite elements method based simulations and resulted in a successful matching of the experimental UV–visible spectra of ligand-coated silver nanoparticles. The computational matching of the surface plasmon resonance (SPR) band reveals both a ligand-type dependence of the effective plasma frequency and a size dependence of the SPR damping effect within the modeled nanoparticle. The observed differences of effective plasma frequency between thiol and amine-coated nanoparticles are consistent with the already known stronger bonding of thiols on silver compared to amines. The significant increase of the damping effect at the surface of the nanoparticle when increasing their size suggests an inverse relation between the ligand packing density and the nanoparticle size, which is supported by the expected influence of the surface curvature radius on the ligand packing