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There is a increasing emphasis in today’s world to use environmental friendly solutions for tribological and lubrication purposes. Use of water as a lubricant presents a cost effective and easy method of bio friendly lubrication. But, as water has low viscosity, it is necessary that the materials used in water lubricated contacts perform exceedingly well in boundary lubricated conditions. Polymer Based Materials (PBMs), are one such group of materials which have been proven to perform well in such conditions. In particular, Ultra High Molecular Weight Polyethylene (UHMWPE) has been extensively used in water lubricated contacts. But, PBMs still suffer from wear and related problems and there is room for improvement. Various methods have been tried with mixed results to improve the qualities of polymers and consequently their performance in water lubricated contacts. One such method is by inclusion of fillers. Conventionally, micron sized fillers have been used to form composites with a polymer resulting in materials with better properties. Recently, nanometer sized reinforcements have been attracting more attention due to their unique mechanical and tribological properties. Combining micrometer and nanometer sized filler in a polymer composite could help form materials with excellent properties. Such composites would be termed as a hybrid material. Therefore, the aim of this project and thesis is to experimentally investigate the influence and interaction of micro and nano carbon-based fillers on tribological behaviour of UHMWPE composites and provide further understanding of the mechanisms involved.

Les siRNA se sont des agents actifs et spécifiques couramment utilisés en thérapie génique. L’intérêt d’utiliser des nanoparticules en tant que vecteurs des siRNA est leur capacité à protéger ces derniers de la dégradation par les nucléases et également de leur permettre d’être délivrés au niveau de leur cible thérapeutique. Afin d’appuyer cette théorie, ce travail s’est concentré sur un modèle cellulaire de sarcome d’Ewing, dans le but de mettre au point un nouveau système galénique pour le transport de siRNA formé des nanoparticules bifonctionnelles de diamants fluorescentes recouvertes par des polymères cationiques. Ces nano-vecteurs sont capables d’induire efficacement l’inhibition de l’expression de l’oncogène EWS-Fli1 dans les cellules en culture s’ils transportent des siRNA dirigés contre ce gène. Par ailleurs, les nanodiamants, grâce à leurs propriétés de fluorescence stable et intense, ont constitué des outils de détection permettant de suivre leurs voies de pénétration, leur biodistribution cellulaire, ainsi que la cinétique de libération des siRNA dans le cytoplasme. Enfin, un modèle de nanodiamants fonctionnalisés par le polyéthylenimine a été choisi pour la poursuite des travaux biologiques en raison de son efficacité de vectorisation. / SiRNA are powerful and commonly used agent for the specific inhibition of gene expression. They need to be vectorized by nanoparticles to facilitate cell penetration and their protection from degradation in biological media. At first, cationic nanodiamonds coated with cationic polymers were developed and were able to adsorb siRNA on their surface. Using antisense siRNA against the oncogene EWS-Fli1, nanodiamonds allowed to efficiently induce the inhibition of expression of the oncogene EWS-FLI1 in cultured Ewing sarcoma cells. As a second goal of this study, the fluorescence of red color center created in the nanodiamonds was used to follow their pathways, their cellular biodistribution and the kinetics of release of siRNA into the cytoplasm. In conclusion, nanodiamonds functionalized by polyethylenimine showed a better transfection efficiency and were chosen for further biological studies.

Analysis of the electronic structures of nitrogen-doped, amorphous carbon samples and of nanodiamond films are carried out in order to determine their sp2 bonding concentration. The amorphous carbon samples under consideration are deposited onto polytetrafluoroethylene (PTFE) polymer substrates by hot wire plasma sputtering of graphite in varying nitrogen concentration atmospheres. The deposition or modification of the substrates surface may lend itself to increasing hardness and wear resistance. Eventually these polymer substrates may be used for applications in the field of biomaterials, focusing on cardiovascular surgery, where a low blood/surface interaction is important. The primary technique used in this study is x-ray absorption spectroscopy, measured at the Advanced Light Source synchrotron at the Lawrence Berkeley National Laboratory, Berkeley, USA. A method of analyzing these spectra was then developed to determine the sp2 bonding concentrations in carbon films. Through this newly developed analysis method, the sp2 bonding concentrations in these samples increases from 74 to 93% with growing nitrogen doping. The diamond films presented here are deposited on silicon wafer substrates in a methane atmosphere by microwave plasma deposition. Various deposition conditions, such as bias voltage and methane atmosphere concentration, affect the purity of the diamond film. This analysis reveals sp2 bonding concentrations in these samples from, typically, a few percent to 25%.

Analysis of the electronic structures of nitrogen-doped, amorphous carbon samples and of nanodiamond films are carried out in order to determine their sp2 bonding concentration. The amorphous carbon samples under consideration are deposited onto polytetrafluoroethylene (PTFE) polymer substrates by hot wire plasma sputtering of graphite in varying nitrogen concentration atmospheres. The deposition or modification of the substrates surface may lend itself to increasing hardness and wear resistance. Eventually these polymer substrates may be used for applications in the field of biomaterials, focusing on cardiovascular surgery, where a low blood/surface interaction is important. The primary technique used in this study is x-ray absorption spectroscopy, measured at the Advanced Light Source synchrotron at the Lawrence Berkeley National Laboratory, Berkeley, USA. A method of analyzing these spectra was then developed to determine the sp2 bonding concentrations in carbon films. Through this newly developed analysis method, the sp2 bonding concentrations in these samples increases from 74 to 93% with growing nitrogen doping. The diamond films presented here are deposited on silicon wafer substrates in a methane atmosphere by microwave plasma deposition. Various deposition conditions, such as bias voltage and methane atmosphere concentration, affect the purity of the diamond film. This analysis reveals sp2 bonding concentrations in these samples from, typically, a few percent to 25%.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第19002号 / 工博第4044号 / 新制||工||1622 / 31953 / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 白川 昌宏, 教授 田中 庸裕, 教授 濵地 格 / 学位規則第4条第1項該当

Les nanodiamants issus de la détonation ont été découverts en URSS dans les années 1960. Cette technique de synthèse permet de générer pendant un temps très court, des hautes pressions et hautes températures. Les particules de diamant formées, possèdent un diamètre moyen de 5nm et disposent d’une riche chimie de surface. Celle-ci a été étudiée et les sites oxygénés ont été quantifiés par diverses méthodes. Ces sites ont ensuite été modifiés par le greffage (par des liaisons covalentes ou métal-ligand) de molécules organiques (porphyrines, phthalocyanines, ...). Des techniques ont été développées afin de déterminer le rendement du greffage chimique. Les matériaux synthétisés ont ensuite été valorisés par leur utilisation comme filtres aux propriétés non-linéaires pour de la protection laser. Les propriétés colloïdales des nanodiamants ont également été étudiées, afin de séparer les agrégats des particules unitaires et procéder à des dépôts contrôlés. Grâce à un procédé présenté dans ce manuscrit, il a été possible de déposer de manière uniforme des particules unitaires de nanodiamant en monocouche extrêmement dense. Ces dépôts ont été utilisés pour l’élaboration de capteurs. / Detonation nanodiamonds were discovered in the early 60’s in URSS. This synthesis technique allows the generation of high pressures and high temperatures in a short duration. The resulting nanodiamond particles have a mean diameter of 5nm and a developed surface chemistry. The surface composition has been determined and the oxygenated sites were quantified by the use of various methods. These sites have been used to graft (by the use of covalent or metal-ligand bonds) different organic molecules (porphyrins, phthalocyanins, …). Different techniques enabled the determination of the chemical grafting yield. The resulting materials have been used as non-linear filters against laser threat.The nanodiamond colloidal properties have also been studied, to separate the aggregates from the unitary particles and well control their deposition. A method has been described in this manuscript, enabling the uniform deposition of unitary nanodiamond particles forming an extremely dense monolayer. These deposits have been used for sensors applications.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22895号 / 工博第4792号 / 新制||工||1749(附属図書館) / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 SIVANIAH Easan, 教授 田中 庸裕, 教授 今堀 博 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Currently tribological laboratories are looking for a new type of solid ingredients, to create a lubricating composition with minimal friction, heat resistant, with particles well dispersed in oils, sedimentation stable, improving the running properties and to minimize the concentration of solids. Nanodiamonds (DND) could exhibit the possible solution. These particles (in nanometers size) have very good physical and chemical properties, high hardness and resistance. The main advantages are effectiveness at low concentrations, compatibility with various types of oils or environmental safety (carbon additive, unlike metal) in a comparison with other types of additives. However, it is necessary to study these ingredients. The aim of research was to examine the influence of diamond nanoparticles on friction in a lubricated contact (elastohydrodynamic mode). Using tribological equipment, 3D optical profilometer and a microscope, we compared and evaluated using oil with diamond nanoparticles as well as without them. The research focused on the behavior of nanoparticles in contact and the effect they have on friction. To assess these properties of nanodiamonds, EHD optical tribometer was used (this is a device designed for the study of thin lubricating films). 3D optical profilometer and a microscope to assess the wear. And to determine the relationship between the coefficient of friction (COF) and time, Mini Traction Machine was used.

Quartz Crystal Microbalance (QCM) is a sensitive and effective technique to analyze mass changes at the interface between a solid material and a liquid environment. In this Master thesis, QCM was employed for evaluating the interactions between selected degradable polymers and nanodiamond particles (nDP), fibronectin and the growth factor BMP-2.   Many parameters must be adapted to allow QCM measurements involving degradable polymers. These parameters were then tailored to allow QCM measurements with PLA, poly(LLA-co-CL), poly(TMC-D-LA) and PS.   Moreover, QCM provides quantitative measurements of protein adsorption on degradable polymers. The behavior of PLA and poly(LLA-co-CL) was further evaluated and compared with respect to protein adsorption. This behavior was demonstrated to be different for the two polymers considered and to be dependent on protein concentration in solution.   Eventually, exploiting QCM it was also possible to assess the relationship between nDP and the adsorption of fibronectin and BMP-2 onto PLA and poly(LLA-co-CL).