Orientador: Paulo José Samenho Moran / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-21T16:43:49Z (GMT). No. of bitstreams: 1 Paula_BrunoRicardoSilvade_M.pdf: 10291593 bytes, checksum: c054e04292035c00a7e70ac53eea2231 (MD5) Previous issue date: 2012 / Resumo: Nesse projeto investigou-se o uso de líquidos iônicos na preparação de compostos carbonílicos a,b-insaturados por meio da condensação de Knoevenagel e na biorredução dos produtos sintetizados. Na primeira etapa do projeto, estudou-se a aplicação de um protocolo desenvolvido pelo grupo de pesquisa para a condensação de Knoevenagel entre b-cetoésteres e aldeídos aromáticos em líquidos iônicos. Utilizaram-se os líquidos iônicos [bmim(PF6)] e [bmim(NTf2)], e em ambos os casos, obtiveram-se rendimentos de moderado a alto para as condensações envolvendo o acetoacetato de etila e o 4-cloroacetoacetato de etila. Os produtos obtidos, que em todos os casos foram misturas de diastereoisômeros, foram separados e caracterizados individualmente, e a configurações das olefinas (E ou Z) puderam ser determinadas com base na cristalografia de raios-X de dois dos compostos preparados, e posterior comparação dos espectros de RMN de C de todos os compostos sintetizados. O acetoacetato de etila forneceu como isômero majoritário o Z, enquanto o 4-cloroacetoacetato de etila forneceu como isômero majoritário o E. Na segunda etapa do projeto, estudaram-se as biorreduções dos compostos preparados em sistemas bifásicos água/líquido iônico hidrofóbico. Em geral, verificou-se que na biorredução dos derivados do acetoacetato de etila por Saccharomyces cerevisiae, a existência de um sistema bifásico fez com que houvesse a redução da olefina, mantendo a carbonila intacta, enquanto no sistema monofásico (aquoso) houve a redução tanto da olefina quanto da carbonila. O comportamento da reação de biorredução foi bastante sensível a natureza do anel aromático, sendo que em alguns casos os produtos de retro-Knoevenagel foram formados em quantidades significativas. No caso do 2-benzilidenoacetoacetato de etila, pôde-se verificar que um comportamento semelhante foi observado em termos de quimiosseletividade para a redução dos derivados do acetoacetato de etila na presença de uma resina acrílica (Amberlite XAD-7). No caso dos derivados do 4-cloroacetoacetato de etila, as biorreduções por Saccharomyces cerevisiae, Saccharomyces boulardii, Candida albicans, Pichia stipitis e Geotrichum candidum forneceram como majoritários os produtos de retro-Knoevenagel. No caso da biorredução por Rhodotorula glutinis, houve apenas um aumento do tempo de reação, com manutenção da redução dos dois grupos funcionais / Abstract: In this project, we studied the use of ionic liquids in the preparation of a,b-unsaturated compounds by the Knoevenagel condensation, and in their bioreductions by yeasts. In the first stage, a methodology developed by our research group for the a-methylenation of carbonyl compounds in ionic liquids was applied to the condensation of b-ketoesters and aromatic aldehydes. In condensations involving ethyl acetoacetate and 4-chloroacetoacetate, moderate to high yields were obtained using [bmim(PF6)] and [bmim(NTf2)]. In all cases, diastereomeric mixtures were obtained, and both isomers were separated and characterized individually. The determination of the olefin configuration was based on X-ray crystallography of two of the synthesized compounds, and further comparison of their C NMR spectra with those of the remaining products. Although the reactions proceeded with only low to moderate diastereoselectivity, it was noteworthy that, whereas ethyl acetoacetate favored the Z isomer as the major reaction product, ethyl 4-chloroacetoacetate favored the E isomer as the major one. In the second stage, the bioreductions of the synthetized compounds in water/[bmim(PF6)] were studied. For the reduction of ethyl 2-benzylideneacetoacetate by Saccharomyces cerevisiae, the use of a water/[bmim(PF6)] system resulted in the maintenance of the C=O bond, with reduction only of the C=C bond. In contrast, in water, both the C=O and C=C bonds are reduced. When other acetoacetate derivatives were employed, it was noted that both reaction rates and the byproducts varied greatly varying the aromatic ring. When the reaction was performed in a aqueous system with the substrate adsorbed in an acrylic resin (Amberlite XAD-7), a similar result in terms of chemoselectivity was observed. When reductions of ethyl 2-benzylidene-4-chloroacetoacetate were carried out with Saccharomyces cerevisiae, Saccharomyces boulardii, Candida albicans, Pichia stipitis and Geotrichum candidum, the major observed products were those of a retro-Knoevenagel reaction. Only when Rhodotorula glutinis was employed, the major products were the bioreduction ones. In this case, however, the use of a water/[bmim(PF6)] system only resulted in a decrease of both C=O and C=C reduction rates, but not in a favoring of C=C reduction / Mestrado / Quimica Organica / Mestre em Química

In this thesis, the newly released framework Ionic 2, which claims to fix the problems cross platform frameworks has suffered from concerning bad performance and bad user experience, has been evaluated. The study has focused on the Android platform by comparing a native developed application to an Ionic 2 developed application. The comparison has been made on performance and user experience. As an extent, Ionic 2 are also compared to another evaluation study made for React Native, to see how the two frameworks differ, both performance wise and user experience wise. The native application performs better in all performance tests, even though the difference only was a few percent for memory usage and battery consumption. In the user tests, the result was of different nature. Some users did not notice any differences between the applications, whilst some had big concerns with how the application behaved. The overall conclusion is that Ionic still has some way to go to compete with native applications. If considering using Ionic 2, you need to be aware of the flaws it has. From the data gathered for this study, React Native is considered to be better than Ionic, but with new updates coming continuously, Ionic is improving every day.

Les nanoparticules (NPs) métalliques possèdent des propriétés physiques inhabituelles et suscitent un grand intérêt pour divers domaines d’application. En particulier, les NPs de métaux magnétiques offrent de nombreux avantages dans une grande variété d’applications technologiques, médicales et en catalyse. Généralement, ces applications nécessitent de fabriquer des NPs de taille et de composition contrôlées. Cette thèse vise à démontrer que de telles NPs peuvent être obtenues par décomposition de précurseurs organométalliques (OM) dans des solvants d’un genre particulier, les liquides ioniques (LIs). Ce sont des sels possédant un très bas point de fusion (inférieur à 100°C) et qui possèdent des propriétés uniques, dont celle de stabiliser des nano-objets. Pour y parvenir, des précurseurs OM des métaux d’intérêt (Co et Fe) ont été identifiés. Des Co-NPs ont pu être synthétisées de manière contrôlée : elles possèdent une structure cristalline du e-Co et les propriétés superparamagnétiques attendues pour le Co(0). Dans le cas du Fe, une oxydation partielle des NPs n’a pu être évitée. La seconde partie du travail s’est donc concentrée sur l’obtention de NPs bimétalliques CoM, avec M=Ru ou Pt. Dans le cas de Ru, toutes les synthèses ont conduit à des NPs bimétalliques, tandis que seule une décomposition simultanée des deux précurseurs de Co et Pt a permis de former des CoPt-NPs. Ces NPs pourraient permettre de fabriquer des dispositifs de stockage de données plus performants ou des catalyseurs moins onéreux / Metallic nanoparticles (NPs) exhibit unique physical and chemical properties. However, their use is conditioned by the ability to control their size and structure. The decomposition of organometallic (OM) precursors under H2 is efficient to generate metallic NPs in organic solvents, but also in ionic liquids (ILs). We have shown that in the latter media, the size can be finely tuned without adding stabilizing agents. Moreover, the resulting “naked” metallic NPs are suitable for catalysis or further reaction with a second OM precursor to form bimetallic NPs.In this work, we applied this knowledge to the synthesis of mono- and bimetallic NPs in imidazolium-based ILs C1CaImNTf2. CoNPs with a diameter of ca. 4 nm were successfully synthesized by decomposition of [Co(?3-C8H13)(?4-C8H12)] under H2. Structural analysis and magnetic characterizations demonstrated that these NPs are metallic and, as expected for this size, superparamagnetic. This approach was extended to the synthesis of bimetallic CoPt and CoRu NPs. It turned out that the best strategy is probably to simultaneously decompose the Co and Pt (or Ru) precursors. This reaction provides monodisperse suspensions of NPs, a good indication that they are bimetallic. Further structural characterizations, in particular using anomalous SAXS, are also considered to elucidate their structure

Submitted in fulfilment of the academic requirements of Masters in Applied Sciences (Chemistry), Durban University of Technology, 2017. / This thesis forms part of the Durban University of Technology Thermodynamics Research Unit’s project which is aimed at developing a method for determination of the liquid-liquid equilibria (LLE) data for the azeotrope {methanol + water} with an ionic-liquid (IL) using DSA5000M to assess the efficiency of the ionic liquid to be used in liquid-liquid extractions for the recovery and recycling of methanol from petroleum refinery. The objective of this study was to determine the liquid-liquid equilibria data of the azeotrope {methanol + water} using 1-ethyl-3-methylimidazolium ethyl sulfate ionic liquid with the intention to recycle methanol from the Fischer-Tropsch (FT) process by- products in petroleum industries and to utilize it in gasoline additives in a new methanol to gasoline (MTG) petroleum process. LLE studies of systems containing alcohols and water are important due to the increasing demands of oxygenated compounds to produce lead free gasoline. Light alkanols such as methanol and ethanol are reported to be suitable compounds in order to produce lead free gasoline, but the use of methanol in gasoline blends can cause phase separation problems in: 1. dry conditions, these are due to its partial solubility in saturated hydrocarbons. 2. the presence of water from ambient humidity or in storage tanks, this depend on unfavourable distribution factor between aqueous and the hydrocarbon phase. To determine the possibility of separating methanol from water using ionic liquid, the liquid-liquid equilibria data was determined at room temperature, T = 298.15 K and atmospheric pressure to investigate whether it separate from water and/or a non-phase separation if it is used as an additive. The experimental data generated was compared to that of the literature for the system {methanol (1) +toluene (2) + dodecane (3)} and showed good agreement with the literature data with only maximum deviation of ± 0.0015 in the mole fraction using density calculations and ± 0.0092 in the mole fraction when using refractive index calculations The selectivities and distribution coefficients for this system were also calculated and the maximum deviation between the two methods (nD and ρ) was ± 1.33 in selectivities and found to be ±0.001 for distribution coefficients. The maximum deviation in distribution coefficients from literature when using nD calculations for system 1 was ±0.04 and ±0.01 for ρ. For the selectivity values the deviation from that of literature of nD when compared was found to be ± 1.28 and 0.29 for ρ respectively. The selectivity values from the density calculations were found to be in the range 2.82 – 7.66 for this system with the distribution coefficient values reported in the range 0.17 – 0.23. In the second system (system 2) the generated experimental data was also compared to that of the literature for the system {water (1) + methanol (2) + cyclohexane (3)} and in good agreement with literature values with only maximum deviation of ± 0.0091 in the weight fraction based on density calculations. The selectivities and distribution coefficients were also calculated and the maximum deviation between the literature and the experimental data was computed to be at ± 0.0003 for selectivity and ±0.09 in distribution coefficient. The selectivity values were found to be in a range 0.00 - 0.04 for this system and were constant throughout the phases but significantly less than one; with the distribution coefficient values in the range 0.00 – 0.008. For 1-ethyl-3-methylimidazolium ethyl sulfate system (Ionic liquid system) the selectivity values were not constant throughout the two-phase region and the values were found to be in the range 0.63 -0.99 still below one which indicates that the ionic liquid used in this study could not be considered as a potential solvent for the separation of the investigated azeotrope. The distribution coefficients for this system were determined and found to be in the range 0.23 – 0.74. The certainty and reliability of experimentally measured tie-line data was ascertained by applying Othmer-Tobias (OT) correlations and the Non-Random, Two Liquid (NRTL) parameters. The OT correlations for system 1 was linear and indicated the certainty of the five tie-lines prepared for this system. In system 2 the OT correlation was not linear and indicated extensively high errors as well as high systematic multiplicative and additive errors in calculations of mole fractions. For the IL system the OT correlation was linear throughout the whole tie-line range and indicated the adequate precision, which denotes that the investigation was carried out with minimal random and systematic errors and indicated the efficiency of the DSA 5000 M to generate the liquid-liquid equilibria data. All the ternary systems were well correlated and in good agreement with the estimated NRTL data. It was only system 1{methanol (1) + toluene (2) + dodecane (3)} that gave a high maximum deviation ( %RSMD) of 1.288 when using the RI measurements with the minimum error margin of 0.6320, this account as to why RI measurements were not applied in other systems (system 2 and ionic liquid system). Similarly for the same system; system 1{methanol (1) + toluene (2) + dodecane (3)} when using the density measurements; the NRTL model gave a maximum deviation of 0.5620 and minimum error margin of 0.2590. The NRTL obtained for system 2 {water (1) + methanol (2) + cyclohexane (3)} gave the maximum deviation of 0.5752 and minimum error margin of 0.0127. The NRTL for the ionic liquid ternary system {[EMIM][EtSO4](1) + methanol (2) + water (3)}showed a good agreement between the experimental data and the NRTL model tie- line data with the %RSMD of 1.0201 on the upper limit and 0.1620 as a lower deviation. / M

Submitted in the fulfilment of the requirement for the Degree of Doctor of Philosophy: Chemistry, Durban University of Technology, 2016. / The work conducted in this study comprised three aspects: syntheses, characterizations, and multi-component liquid-liquid extractions. The main objectives of the project were: (1) to evaluate the efficacy and efficiency of ionic liquids to extract aromatic components from catalytic reformates and paint solvent wastes, and (2) to validate the method(s) used in this project to qualitatively and quantitatively analyze the aromatic molecules (BTEX) in multi-component mixtures. Therefore, this research critically investigated the major effects of the chosen ionic liquids as extractive solvents for the recovery of BTEX components from model and industrial organic mixtures. The project was concerned with the nature of solvents currently used in most industries for the separation by extraction of aromatic hydrocarbons from non-aqueous or organic mixtures. Most solvents currently employed for this purpose are highly volatile; hence they contribute significantly towards environment pollution. In addition, the extraction efficiency of these conventional solvents is limited only to mixtures containing aromatic hydrocarbons of 20% or more. Furthermore, conventional solvents are organic compounds which are generally toxic, flammable, and expensive to recover or regenerate from extract phases due to methods which involve several steps. In addition, they demand high energy input for the distillation steps. used in the analysis of aromatic components were evaluated for validity. According to the literature no such work was carried out by previous researchers. The study targeted four ionic liquids, namely, 1-ethyl-3-methylimidazolium ethyl sulphate [EMIM][ESO4], 1-ethyl-3-methylpyridinium ethyl sulphate [EMpy][ESO4], 1- Butyl-1-methyl-2-pyrrolidonium bromide [BNMP][Br], and 1,1-Dimethyl-2- pyrrolidonium iodide [MNMP][I] in an attempt to address this concern. These ionic liquids were synthesized and characterized in our laboratories using previously accepted methods. After synthesis and purification, they were characterized by techniques including FTIR, 1H-NMR, and 13C-NMR. The densities and moisture content of both the synthesized and standard ionic liquids were also determined using density meters and Karl-Fischer apparatus, respectively. The extractions were carried out on both the model and industrial mixtures using ionic liquids. Each ionic liquid was mixed with a target mixture in a water-jacketed vessel and then stirred vigorously at constant temperature achieved by a thermostatically controlled water-bath. After a selected period of time the operation was stopped and the resulting mixture was left to stand overnight to allow phase equilibration to be reached. The two phases were then separated and analyzed for the content of individual aromatic components in each phase using GC-FID calibrated with external standards of the components present in the mixtures being investigated. According to the results obtained from the synthesis and characterization methods the percentages yield of ionic liquids were reasonably high (> 95%). In addition, spectral studies showed high purity with fewer traces of impurities based on the observed relative intensities. Results from GC-FID indicated a relatively lower concentration of aliphatic hydrocarbons in the extract phase. On the other hand, the concentrations of aromatic II components in the extract phase were relatively higher than those of aliphatic hydrocarbons. The results obtained from the three extraction stages showed the total recovery of greater than 50% for the aromatic components. This suggests that at least six extraction stages would be required in order to achieve a total recovery of 100% aromatic components which is an indication of good efficiency. Also noticeable was that the first extraction stages for all ionic liquids recovery values were much higher than those values obtained from successive stages which showed approximately the same extraction results. In most experiments, 1-ethyl-3-methylpyridinium ethyl sulphate gave higher recovery values than the other three ionic liquids. It was also noted that the recovery values obtained from the extractions performed on model mixtures of the entire concentration range (0.5 – 25%) of individual aromatic components did not show any significant difference. Proportional difference in recoveries occurred across the entire concentration range of model mixtures. The results also indicated that the solubility of aromatic hydrocarbons in the ionic liquids decreases in the order: benzene > toluene > ethyl benzene >xylenes. This phenomenon is attributed to a decrease in π-π, cation- π, cation- anion interactions occurring between the ionic liquid and each of the aromatic molecules in this order. The recovery values for BTEX ranged from 80 to 120 % by volume for the three extraction stages. This is in line with results previous research studies carried out on liquid-liquid extractions involving ternary systems containing only one aromatic component in each mixture. Therefore this study shows that ionic liquids are capable extraction solvents for simultaneous recovery of the aromatic components from any organic mixtures containing low to high BTEX concentrations. In addition, the outcomes of this project have proved that ionic liquids are economically viable as potential extraction solvents since they can be easily recycled and reusable many times without any noticeable degradation. The results of this study are envisaged to make significant contributions to the current research efforts aimed at achieving greener environments and minimization of global warming. The findings of this project are also geared to boost the economy of our country through job creation using economically viable methods. / D

Submitted in fulfillment of the requirements for the degree of Doctor of Technology: Chemistry, Durban University of Technology, Durban, South Africa, 2017. / The thermodynamic properties of mixtures involving ionic liquids (ILs) with organic acid (acetic acid or propanoic acid) or acetonitrile at different temperatures were determined. The ILs used were imidazolium-based: 1-ethyl-3-methylimidazolium ethyl sulphate [EMIM]+[EtSO4]-, 1-butyl- 3-methylimidazolium thiocyanate [BMIM]+[SCN]- and 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide ([BMIM]+[Tf2N]-. The ternary excess molar volume (V E ), isentropic compressibility (ks) and deviation in isentropic compressibility ( ks123 ) were determined for four ternary liquid mixtures of {[EMIM]+[EtSO4]- or [BMIM]+[SCN]− + acetic or propionic acid + acetonitrile} at different temperatures (293.15, 298.15, 303.15, 308.15 and 313.15) K and at a pressure of 0.1 MPa with aid of the experimental density (ρ), speed of sound (u) data. The calculated data were correlated by using the Cibulka equation with the help of Redlich–Kister parameters obtained from fitting the Redlich–Kister equation for the corresponding binary systems. Furthermore, the density and speed of sound were also measured for eight corresponding binary systems at the same experimental conditions. The binary excess molar volume, isentropic compressibility and deviation in isentropic compressibility were also calculated for measured systems and fitted to the Redlich–Kister equation to obtain the Redlich–Kister parameters as well as to check the accuracy of measured data which were used to correlated experimental data using Cibulka equation. These results were discussed, in terms of how the sign and magnitude of thermodynamic functions were influenced by the addition of a third component to liquid systems. Also, the possible molecular and pair-wise interactions between component molecules and the effect of temperature on the thermophysical and thermodynamic properties were predicted. In addition, the work focussed on application of ([BMIM]+[Tf2N]-) ionic liquid for the separations of (alkane/aromatic), (alkane/alk-1-ene), (cycloalkane/aromatic) and (water/alkan-1-ol) using gas- liquid chromatography (GLC) technique. The activity coefficients at infinite dilution, , for 31 organic solutes (alkanes, cycloalkanes, alkenes, alkynes, aromatics, alkanol and ketones) and water in ionic liquid were measured at temperatures of (323.15, 333.15, 343.15, 353.15 and 363.15) K. Stationary phase loadings of (42.83 and 68.66) % by mass were used to ensure repeatability of E , measurements. Partial molar excess enthalpies at infinite dilution, H1 , were also determined. The selectivities, S , and capacities, k , were determined for the above separations. The separating ij j ability of the investigated ionic liquid was compared with previously investigated ionic liquids and industrial solvents such as sulfolane, n-methyl-2-pyrrolidine (NMP) and n-formylmorpholine (NFM). The results obtained suggested that in general, the [BMIM]+[Tf2N]− had outperformed the conventional solvents such as sulfolane, NMP and NFM in terms of selectivity, while the [BMIM][Tf2N] had in general, performed better overall when the performance index was used for comparison. / D

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17525号 / 工博第3684号 / 新制||工||1560(附属図書館) / 30291 / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 佐藤 啓文, 教授 今堀 博, 教授 山本 量一 / 学位規則第4条第1項該当

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17587号 / 工博第3746号 / 新制||工||1571(附属図書館) / 30353 / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 安部 武志, 教授 陰山 洋, 教授 阿部 竜 / 学位規則第4条第1項該当

Electrical and thermal conductivities of the yttria-stabilised zirconia/alumina (YSZ/Al2O3) composites and the yttria-zirconia-ceria (YSZ-CeO2) solid solutions are studied in this thesis. The electrical conductivity of the YSZ/Al2O3 composites decreases with an increase in the volume fraction of Al2O3 and exhibits typical percolation behaviour. The electrical conductivity of the YSZ/Al2O3 interface is higher than that of the YSZ grain boundary, but lower than that of the YSZ grains. The thermal conductivity of the YSZ/Al2O3 composites increases with an increase in the Al2O3 volume fraction, and it can be fitted well to the Maxwell theoretical model, which indicates the absence of obvious interfacial thermal resistances in the composites. The low interfacial thermal resistance of the YSZ/Al2O3 interface is due to the 'clean' and coherent nature of the YSZ/Al2O3 interface, along with the small difference between the elastic properties of YSZ and Al2O3. The electrical conductivity of the [(ZrO2)1-x(CeO2)x]0.92(Y2O3)0.08 (0 ≤ x ≤ 1) solid solutions has a 'V-shape' variation as a function of the mole ratio of CeO2 (x). In the ZrO2-rich region (x < 0.5), CeO2 doping increases the concentration of defect associates which limits the mobility of the oxygen vacancies; in the CeO2-rich region (x > 0.5), the increase of x increases the lattice parameter, which enlarges the free channel for oxygen vacancy migration. A comparison of the YSZ-CeO2 solid solutions with the YSZ-HfO2 series indicates the ionic radius of the tetravalent dopant determines the composition dependence of the ionic conductivity of the solid solutions.The thermal conductivity of the [(ZrO2)1-x(CeO2)x]0.92(Y2O3)0.08 (0 ≤ x ≤ 1) solid solutions also has a 'V-shape' variation as a function of the mole ratio of CeO2 (x), which indicates an incorporation of Zr4+ and Ce4+ can effectively decrease the thermal conductivity of the end members YSZ and yttria-doped ceria (YDC). In the ZrO2-rich region (0 ≤ x ≤ 0.5), the thermal conductivity is almost temperature independent; in the CeO2-rich region (0.5 ≤ x ≤ 1), it decreases obviously with increasing temperature. By calculating the phonon scattering coefficients, it is concluded that the composition dependence of the thermal conductivity in the ternary solid solutions is dominated by the mass difference between Zr and Ce at the cation sites, whereas the temperature dependence is determined by the order/disorder of oxygen vacancies at the anion sites.

Le contrôle actif d’écoulement est une voie envisagée actuellement pour améliorer les caractéristiques aérodynamiques des véhicules aériens ou terrestres. La diminution de la traînée (force opposée au mouvement) est notamment visée, ce qui permettrait de baisser la consommation en énergie entraînant ainsi une réduction des émissions polluantes. Depuis une dizaine d’années, les actionneurs plasmas sont utilisés comme dispositifs de contrôle. À Orléans, ils sont basés sur l’utilisation d’une décharge à barrière diélectrique créant à sa surface un plasma qui induit un écoulement de quelques km h-1 : le vent ionique. L’actionneur plasma est caractérisé avec l’étude des différents régimes de décharge. Celui où des arcs énergétiques apparaissent est analysé. La température de surface de l’actionneur est également étudiée en fonction de plusieurs paramètres. Elle reste inférieure à 100 °C, ce qui confirme que les effets des actionneurs plasmas sur un écoulement ne sont dus qu’au vent ionique. Une caractérisation du vent ionique permet aussi de confirmer le lien entre le vent ionique et l’extension du plasma : deux phases distinctes existent, pendant lesquelles il est créé. Le contrôle de la transition d’une couche limite de Blasius est effectué sur une géométrie de type plaque plane. En fonction de la position de l’actionneur ou de la puissance consommée, le recul, le déclenchement précoce ou le cas sans effet est obtenu. Le mécanisme d’action est identifié et est lié à une excitation de l’écoulement qui devient plus ou moins sensible aux ondes de Tollmien-Schlichting. La fréquence de fonctionnement de l’actionneur apparaît comme le paramètre principal pour ce type de contrôle. Une nouvelle géométrie d’actionneur est proposée et caractérisée. La décharge conserve des propriétés identiques au cas classique et le sondage du vent ionique par un moyen de mesure 3D permet de montrer le gain en vitesse et l’existence de structures 3D susceptibles de contrôler plus efficacement un écoulement. / Active flow control is a route currently being considered to improve aerodynamic performances of vehicles (airplanes or cars). Drag reduction (force opposite to motion) is particularly concerned and provides reduction of energy consumption of vehicles what induces low exhaust gases emissions. Plasma actuators are used as control devices since a decade. In Orléans, they are based on the use of surface dielectric barrier discharge which creates plasma on its surface and induces a flow of few km h-1 : the ionic wind. The plasma actuator is characterized with the study of different discharge regimes. One in which sparks occur is analyzed. The actuator surface temperature is also studied in function of several parameters. Surface temperature remains below 100 °C what confirms effects of plasma actuators on the flow are only due to the ionic wind. Characterization of ionic wind has also confirmed the link between induced flow and plasma spread over actuator surface : two distinct phases exist where a flow is every time induced. Transition control of a Blasius boundary layer is performed on flat plate geometry. Depending on plasma actuator position or power consumption, promotion, delay or neutral case are obtained on transition location. The mechanism of action is identified and linked to an excitation of the flow that becomes more or less sensitive to Tollmien-Schlichting waves. The operating frequency also appears as the main parameter for this type of control. New actuator geometry is proposed and characterized. The discharge keeps identical properties to a classical configuration of plasma actuator. Ionic wind measurements by means of a 3D device allow us to show the gain in speed and presence of 3D structures in the induced flow topology what is more effectively to control external flows.