No description available.

No description available.

L’objectif principal de ce travail était l’étude et l’optimisation du procédé de lyophilisation en milieu aqueux et organique de l’ibuprofène. Une étude comparative approfondie a été réalisée à différents stades de la fabrication de l’ibuprofène lyophilisé pour les deux formulations étudiées. Cette étude comparative a été menée sur l’étape de formulation, sur le procédé de lyophilisation (congélation, sublimation, désorption) et sur les propriétés finales du produit (humidité, réhydratabilité, aspect…). On a observé, que l’utilisation comme solvant du mélange eutectique A, correspondant à une composition de 20% en TBA + 80% en eau (% massique), permettait une forte augmentation de la solubilité de l’ibuprofène et conduisait pour les mêmes conditions opératoires (Tshelf et Pc), à une augmentation des cinétiques de séchage d’un facteur 1,8, par rapport aux résultats observés avec la formulation d’ibuprofène à base aqueuse. Par ailleurs, la détermination expérimentale des valeurs des pressions de vapeur à l’équilibre solide-vapeur et de l’enthalpie de sublimation a été effectuée par deux méthodes différentes : la méthode thermogravimétrique et la méthode statique. Ces déterminations nous ont permis de conclure que l’augmentation des cinétiques de sublimation résultait essentiellement des valeurs plus élevées de la pression de vapeur à l’équilibre solide-vapeur et d’une valeur plus faible de l’enthalpie de sublimation de l’eutectique A par rapport à la glace. Ces données thermodynamiques ont aussi été utilisées comme paramètres clefs pour la modélisation de l’étape de sublimation sous Comsol Multiphysics. In fine, l’optimisation des paramètres opératoires de l’étape de sublimation par la méthodologie du Design Space a conduit à un lyophilisat final d’ibuprofène formulé à base organique qui satisfait entièrement aux critères standard de qualités recherchés (couleur, aspect, résidus de solvants etc). Un développement industriel de la formulation à base de co-solvant organique apparait plus avantageux qu’avec la formulation à base aqueuse. / The main objective of this work was the study and the optimization of the freeze-drying process of ibuprofen with aqueous and/or organic based formulations. A detailed comparative study was realized at different steps of the ibuprofen freeze-drying process for both types of investigated formulations. This comparative study was realized at the succesives stages of freezing, sublimation and desorption and also concerned some properties of the final freeze-dried product (humidity, rehydratability, aspect…). We observed that the use of eutectic A mixture, corresponding to 20 % TBA + 80 % water (mass %) as co-solvent, allowed a strong increase of the solubility of ibuprofen and for the same operating conditions (Tshelf and Pc), led to an increase of drying kinetics values by a factor 1.8 by comparison to aqueous based formulations of ibuprofen. Besides, the experimental determination of equilibrium solid-vapour pressure and of sublimation enthaly values was carried out by using two different methods: the thermogravimetic method and the static method.These determinations allowed to conclude that the increase of sublimation kinetics resulted essentially from the higher equilibrium solid-vapour pressure values and from the lower sublimation enthalpy value of eutectic A by camparison to pure ice values. Next, these thermodynamical data were used as key parameters in the modelling of the sublimation stage under Comsol Multiphysics. In fine, the overall optimization of the operating parameters of sublimation stage was achieved by using the Design Space aproach. It proved that the organic based formulation led to final freeze-died cakes which fulfilled largely the main quality criteria (color, aspect, solvents residues, etc.). Thus, the development of an ibuprofen freeze-drying process with organic based formulation seems more advantageous than an aqueous based formulation process.

<p><p>This thesis concerns design and construction of an ultra high vacuum chamber to fabricate and characterize spintronic devices.  The long term intention is to fabricate spin valve structures with V[TCNE]₂ (hybrid organic inorganic semiconductor room temperature magnet) sandwiched between two ferromagnetic electrodes, which requires better than 10^-8mbar of vacuum. Due to an uncured leak in the chamber, the current vacuum is limited to 4*10^-7mbar. The V[TCNE]₂ thin film prepared in this vacuum, oxidized completely  by  the presence of oxygen during the film growth. Organic magnetoresistance (OMAR) devices which are simple organic diode structures were fabricated and characterized, as they are compatible with high vacuum conditions. A magnetoresistance measurement set up was arranged and the possible problems in fabrication and characterization are analyzed.</p><p> </p><p>To fabricate OMAR devices-ITO/P3HT/Al, RR-P3HT (regio regular poly (3-hexylthiophene)) an effective hole transport polymer with higher hole mobilities was used as an active layer and Al (aluminum) as a cathode. A thermal evaporation setup was added to the vacuum chamber to evaporate Al electrodes. The devices were kept in argon and vacuum environments, while characterizing in dark to suppress the exitons generated by photo illumination. The Organic magnetoconductance of about 1% is observed for the less concentration P3HT (3mg/1ml), and significantly improved to -23% for the high concentration P3HT (10mg/ml) solution. The results support that the negative magnetoconductance is due to the formation of bipolaron under the influence of an external magnetic field.</p><p> </p><p>Finally, suggestions to improve the performance of the vacuum chamber to fabricate and characterize the spintronic devices and OMAR devices are presented.</p></p>

This thesis concerns design and construction of an ultra high vacuum chamber to fabricate and characterize spintronic devices.  The long term intention is to fabricate spin valve structures with V[TCNE]2 (hybrid organic inorganic semiconductor room temperature magnet) sandwiched between two ferromagnetic electrodes, which requires better than 10-8mbar of vacuum. Due to an uncured leak in the chamber, the current vacuum is limited to 4*10-7mbar. The V[TCNE]2 thin film prepared in this vacuum, oxidized completely  by  the presence of oxygen during the film growth. Organic magnetoresistance (OMAR) devices which are simple organic diode structures were fabricated and characterized, as they are compatible with high vacuum conditions. A magnetoresistance measurement set up was arranged and the possible problems in fabrication and characterization are analyzed.   To fabricate OMAR devices-ITO/P3HT/Al, RR-P3HT (regio regular poly (3-hexylthiophene)) an effective hole transport polymer with higher hole mobilities was used as an active layer and Al (aluminum) as a cathode. A thermal evaporation setup was added to the vacuum chamber to evaporate Al electrodes. The devices were kept in argon and vacuum environments, while characterizing in dark to suppress the exitons generated by photo illumination. The Organic magnetoconductance of about 1% is observed for the less concentration P3HT (3mg/1ml), and significantly improved to -23% for the high concentration P3HT (10mg/ml) solution. The results support that the negative magnetoconductance is due to the formation of bipolaron under the influence of an external magnetic field.   Finally, suggestions to improve the performance of the vacuum chamber to fabricate and characterize the spintronic devices and OMAR devices are presented.

No description available.

No description available.

In the growing field of spintronics there is a strong need for development of flexible lightweight semi-conducting magnets. Molecular organic-based magnets are attractive candidates since it is possible to tune their properties by organic chemistry, making them so-called “designer magnets”. Vanadium tetracyanoethylene, V(TCNE)x, is particularly interesting since it is a semiconductor with Curie temperature above room temperature (TC~400 K). The main problem with these organic-based magnets is that they are extremely air sensitive. This thesis reports on the frontier electronic structure of the V(TCNE)x by characterization with photoelectron spectroscopy (PES) and near edge x-ray absorption fine structure (NEXAFS) spectroscopy. It also presents a new and more flexible preparation method of this class of organic-based thin film magnets. The result shows improved air stability of the V(TCNE)x prepared with this method as compared to V(TCNE)x prepared by hitherto used methods.

<p>In the growing field of spintronics there is a strong need for development of flexible lightweight semi-conducting magnets. Molecular organic-based magnets are attractive candidates since it is possible to tune their properties by organic chemistry, making them so-called “designer magnets”. Vanadium tetracyanoethylene, V(TCNE)_x, is particularly interesting since it is a semiconductor with Curie temperature above room temperature (T_C~400 K). The main problem with these organic-based magnets is that they are extremely air sensitive. This thesis reports on the frontier electronic structure of the V(TCNE)_x by characterization with photoelectron spectroscopy (PES) and near edge x-ray absorption fine structure (NEXAFS) spectroscopy. It also presents a new and more flexible preparation method of this class of organic-based thin film magnets. The result shows improved air stability of the V(TCNE)_x prepared with this method as compared to V(TCNE)_x prepared by hitherto used methods.</p>

Organic semiconductors functionalized nanostructures are becoming as promising materials for electronic device applications including organic photovoltaics (OPVs). Perylenediimide (PDI) derivatives have also been known as one of the best n-type organic semiconductors. PDI derivatives can form bulk materials, which are both photochemically and thermally stable and have been widely used in various optoelectronic devices. Due to the formation of high electron mobility of crystalline domains, they prefer to incorporate into a silsesquioxane network. Here, we describe the potential applicability of perylenediimide functionalized silsesquioxane nanoribbons (PDI-dimethyl nanoribbons) as an acceptor for optoelectronic devices. We have developed synthetic procedures to make the PDI-dimethyl nanoribbons by the substitution reaction and the modified Stöber method. The PDI-dimethylethoxy silane precursor was produced in high yield by substituting 3-aminopropyldimethylethoxysilane on perylene-3,4,9,10-tetracarboxylicdianhydride as side chains. The optically active PDI-dimethyl nanoribbons were then formed upon hydrolysis with the certain concentration of ammonium hydroxide as a base. These nanoribbons were characterized using transmission electron microscopy (TEM), elemental analysis, and polarized optical microscopy. The photophysical properties in solution phase were also studied. The synthesis procedure developed here will have a great promise in large-scale manufacturing. Different shapes of PDI-dimethyl nanostructures, such as nanorods, nanochains, and nanoparticles, were discovered while varying the base concentrations. Also the morphologies of these PDI nanostructures were studied using TEM. Future studies will focus on optimizing procedures of PDI-dimethyl nanostructures and exploring new derivatives like perylenediimide dimer functionalized silsesquioxane polymers.