This is Part A of the Thesis. The link to Part B is here: / <p> A radioactive technique to determine interfacial area between solid-liquid and liquid-liquid phases has been investigated. Plastic and liquid scintillators and β-particles from tritium solution were used for this purpose.</p> <p> The tritium β-particles have a very short range (about 5 μm in water), and the surface area of contact between the tritium bearing fluid and the scintillator bearing phase is expected to be proportional to the scintillation count rate, which in turn is proportional to the number of betas crossing the interface from a very thin region.</p> <p> To test this hypothesis, two phases were placed together in a cylindrical plexiglas container, which in turn was placed in an aluminum light-tight housing. The housing also enclosed the photo-multiplier tube (PMT). Pulses corresponding to scintillations due to β absorption were taken from the PMT and fed to a suitable electronic circuit. The count rate was obtained with a multi-channel analyser.</p> <p> It was found that the count rate is a linear function of interfacial area between the tritium bearing fluid and the scintillating material. Some deviation from linearity was however noticed at very low tritium concentration. The count rate remained the same for a given interfacial area regardless of orientation of the surface(s) with respect to the photocathode face.</p> <p> This appeared to confirm the hypothesis that interfacial area could be measured in systems of this type by measuring the scintillation count rate.</p> / Thesis / Master of Engineering (MEngr)

<p>  </p> <p>In the practical applications of colloidal dispersions and suspensions, such as inks, paints, and food industry, the suspended particles must be stabilized, and remain well-dispersed for long times. Particles which are more dense than the suspending media may sediment rapidly, even with no agglomeration occurring, under many conditions of size and density difference. Then, a dispersant would be necessary for stabilization of particle suspensions against both agglomeration and sedimentation, while the suspensions should remain flowable in many applications. Moreover, when many aqueous suspension media may contain salts, the dispersant also needs to be an effective stabilizer against sedimentation under the specific salinity conditions of that application.</p> <p>DDAB (didodecyldimethylammonium bromide) , a cationic double-chain surfactant, forms lamellar liquid crystal phases when dispersed in water. It also easily forms aqueous vesicle dispersions (unilamellar closed particles with an internal solvent compartment) and liposomes (multilamellar vesicles, MLVs, or lamellar liquid crystallites) at relatively low DDAB weight fractions, <em>w</em>_D. To better understand the phase/dispersion behavior of DDAB and the corresponding optical properties, new analytical solutions of the spherical particles have been obtained for the light scattering theory in the Rayleigh (R) and the Rayleigh-Debye-Gans (RDG) regimes, for single and independent scattering. Moreover, the specific Rayleigh ratio <em>R</em>_q** and the specific turbidity <em>t</em>** were derived analytically for both scattering regimes. Spectroturbidimetry (ST) data at 25 °C for DDAB were compared to the <em>t</em>** predictions. <em>t</em>** data for DDAB vesicles are consistent with the RDG predictions, which are also used to estimate the vesicle sizes.</p> <p>For a better understanding of the effect of the preparation method and salinity on the formation of DDAB vesicles, spectroturbidimetry was used to measure the average radius of the unilamellar DDAB vesicles, which were prepared via two different methods in water and in NaBr salt solutions. The radius was ~24 nm after sonication (SS method) and ~74 nm after extrusion/ultrafiltration (SE method). The radii were larger when the vesicles were produced in 10 mM NaBr, ~65 nm for the SS method and ~280 nm for the SE method. The <em>t</em>** values of these vesicular dispersions increased with decreasing <em>w</em>_D values, until a constant value was reached at <em>w</em>_D*, which depends on the preparation method and the dispersion medium. The constant values of <em>t</em>** are indicative of single and independent scattering, and were used to estimate vesicle radii by solving the <em>t</em>** equations derived for the RDG regime. Estimates of the average distances between the vesicles and their corresponding Debye lengths were obtained to evaluate the importance of inter-vesicle electrostatic interactions, which could lead to dependent scattering at higher weight fractions.</p> <p>DDAB prepared with magnetic stirring of multilamellar liposomes, followed by ultrasonication to generate unilamellar vesicles, were found to have very high viscosities at very low shear stresses at DDAB weight fractions <em>w</em>D from 0.025 to 0.027. The vesicles had average diameters ranging from 68 to 80 nm, as previously determined from spectroturbidimetry. These vesicle dispersions stabilized suspensions of monodisperse spherical amorphous silica particles with diameters of <em>d</em>_sed = 454 nm, 691 nm, and 826 nm against sedimentation, at least for several weeks. Similar results were obtained for suspensions, in DDAB vesicle dispersions, of polydisperse, nonspherical, crystalline titania particles with sizes ranging from ca. 96 nm to 156 nm. At the relatively low values of <em>w</em>_D = 0.009 and 0.018, the effective viscosities,<em> h</em>eff, of the DDAB dispersions, determined from the sedimentation velocities, ranged from 1.35 to 1.87 cP and from 4.34 to 5.57 cP, respectively. At <em>w</em>_D = 0.027 for the silica particles with <em>d</em>_sed = 454 nm, or at <em>w</em>_D = 0.025 for all other particles considered, <em>h</em>_eff was essentially infinite, and each vesicle dispersion behaved as a gel at low shear stresses. At higher shear stresses, however, the dispersions were highly shear-thinning, and flowable in a capillary tube under gravity. This behavior is critical for the practical applications of such dispersions for paints and inkjet printing. To further understand the feasibility of the vesicle stabilization mechanism at various NaBr concentrations, <em>w</em>NaBr, the salinity effects on the stabilization of silica particles against sedimentation were also examined. It was found that at <em>w</em>_NaBr < 0.0020 and at <em>w</em>D > 0.060, the DDAB dispersion could stabilize silica particles against sedimentation for at least two weeks. The relationship of the phase and dispersion behavior of DDAB/aqueous NaBr solutions to their stabilizing effectiveness will be further studied.</p> <p>A first discovery of iridescent liquid-like aqueous vesicle dispersions formed from the DDAB is also reported. Although iridescence arises from some solid crystallites, thin films, and colloidal crystals, it had never been observed in systems that are liquid-like. Visual observations and ST at wavelengths of 350 nm to 700 nm were used to determine vesicle sizes and microstructure formation in dispersions for DDAB weight fractions <em>w</em>D between 0.020 to 0.030. The DDAB vesicle dispersions exhibited iridescent colors for <em>w</em>D = 0.023 to 0.027, due to the formation of “soft” crystallites formed by self-assembled vesicles. Effective vesicle radii from 30 to 60 nm were inferred from the ST measurements. The volume fractions of the vesicles <em>f</em>v and their effective volume fractions <em>f</em>v*, which account for the electrostatic double layers around a vesicle, were also estimated. The high values of <em>f</em>v* for the iridescent dispersions indicate that they contain neighboring vesicles with highly overlapping electrostatic double layers, even though their values of <em>f</em>v remain relatively low. Hence, strong electrostatic repulsive interactions arise between the vesicles. These interactions probably drive the formation of the “soft” crystallites, and thus the observed iridescence. Nevertheless, these “soft” crystallites, which could be easily broken up but were quick to reform, remain suspended. Consequently, these vesicle dispersions still flowed as a bulk dispersion with a high viscosity; the dispersion as a whole remained liquid-like or as a “liquid gem”, in contrast to what occurs to the other colloidal crystals made of rigid colloids. Beside their beautiful appearances, these DDAB vesicle dispersions also act as effective stabilizers of dense silica suspensions against sedimentation even at relatively low values of <em>w</em>D. </p>

Cordierite was adhered to molybdenum using various metallic interlayers of copper, nickel, and chromium. The development of a coating adhesion test methodology was required to choose between interface designs. An indentation method was chosen because of ease in testing and availability of fracture mechanics interpretations of test data. The interfacial fracture toughness was determined from indentation load vs. crack length data by examining the residual stress and critical buckling load of the ceramic coatings. The interfacial fracture toughness values obtained using a slightly different indentation analysis agree with those in the literature. Quantitative chemical analysis of the interface microstructure was used to explain differences in interfacial fracture toughness values for samples with different metallic interlayer designs. The best interface design for adhering cordierite glass-ceramic coatings to molybdenum was found to be molybdenum / 2 μm copper / 4 μm chromium / cordierite. / Master of Science

Yes / Results and analysis from investigations into the behaviour of the interfacial layer (Tribolayer) at the friction interface of a brake friction pair (resin bonded composite friction material and cast iron rotor) are presented in which the disc/pad interface temperature has been measured using thermocouple methods. Using a designed experiment approach, the interface temperature is shown to be affected by factors including the number of braking applications, the friction coefficient, sliding speed, braking load and friction material. The time-dependent nature of the Tribo-Iayer formation and the real contact area distribution are shown to be causes of variation in interface temperatures in friction braking. The work extends the scientific understanding of interface contact and temperature during friction braking.

This thesis studies multi-phase flows within two different types of porous nature-inspired material systems: multi-layered feathers and synthetic trees. (1) How multilayered feathers enhance underwater superhydrophobicity. Inspired by ducks, here we demonstrate that air pockets can withstand up to five times more hydrostatic pressure when using stacked layers of synthetic feathers instead of a single layer. The mechanism for the multi-layered enhancement is the more tortuous pathway required for water impalement, which serves to pressurize the air pockets enclosed in the pores. We study this air compression effect using a probabilistic model, in which we quantify the tortuous pathway in stacked feather layers in terms of filled volume fraction of the pores. Our findings suggest that multi-layered coatings could enable robust underwater superhydrophobicity. (2) Oil-Water separation using synthetic trees. In the world's tallest trees, water evaporating from leaves generates enough suction to lift water over 100 m high. Transpiration can similarly be attained in synthetic trees by coupling nanoporous leaves" with conduits mimicking xylem capillaries. Here, we demonstrate that by adding filters to the free ends of the xylem conduits, the hydraulic load generated by transpiration can be used for oil-water separation. The working principle is illustrated using the pressure balance equation for the synthetic tree. / Master of Science / Nature abounds in complex systems and fascinating phenomena that have inspired us, from the way we live to the things we create. The engineering profession is no exception to being inspired by nature. In fact, engineers have created revolutinary robots inspired by animals. The work in this theis draws inspiration from the water-repellant property (superhydrophobicity) of duck feathers and the transpiration process in plants. In the first study, we created 'synthetic feathers' to study how layers of duck feathers are able to sustain superhydrophobicity under water. We discovered the 'layer-effect' that explains enhanced underwater superhydrophobicity. Surfaces covered in such multi-layered feather-like porous structures are potentially useful for reducing drag in underwater applications. In the second study, we develop a 'synthetic tree' that captures the main attributes of the transpiration mechanism in plants. We show that the 'pull' generated by transpiration can be used for oil-water separation. This macroscopic synthetic tree can be useful in cleaning oil spills.

Nanocomposites consist of graphene dispersed in matrices of soft materials are promising thermal management materials. A fundamental understanding of the thermal transport at graphene-soft material interfaces is essential for developing these nanocomposites. In this dissertation, thermal transport at graphene-octane interfaces was investigated using molecular dynamics simulations, and the results revealed several important characteristics of such thermal transport. The interfacial thermal conductance of graphene-octane interfaces were studied first. It was found that the interfacial thermal conductance exhibits a distinct duality: if heat enters graphene from one side of its basal plane and leaves it through the other side, the corresponding interfacial thermal conductance, Gacross, is large; if heat enters graphene from both sides of its basal plane and leaves it at a position far away on its basal plane, the corresponding interfacial thermal conductance, Gnon-across, is small. Gacross is ~30 times larger than Gnon-across for a single-layer graphene immersed in liquid octane. Additional analysis showed that this duality originates partially from the strong, positive correlations between the heat fluxes at the two surfaces of a graphene layer. The interfacial thermal conductance of the graphene-soft material interfaces in presence of defects in the graphene was then studied. The results showed that the heat transfer at the interfaces is enhanced by defects. Estimations based on effective medium theories showed that the effective thermal conductivity of the graphene-based composites could even be enhanced with defects in graphene when heat transfer at the graphene-soft material interface is the bottleneck for the thermal transport in these composites. To describe the interfacial thermal transport at graphene interfaces uniformly, a nonlocal constitutive model was proposed and validated to replace the classical Kapitza model. By characterizing the thermal transport properties of graphene interfaces using a pair of thermal conductance, the model affords a uniform description of the thermal transport at graphene interfaces for different thermal transport modes. Using this model, the data interpretation in time domain thermalreflectance (TDTR) measurements was investigated, and the results showed that the interfacial thermal conductance measured in typical TDTR tests is that of the across mode for thin-layered materials. / Ph. D.

Lors de la fusion du verre, de nombreuses petites bulles de gaz sont produites. L’affinage du verre a pour objectif de faire disparaitre ces bulles par l’ajout d’espèces réactives contribuant à la résorption des bulles ou à une augmentation de leur taille. La modélisation de l’hydrodynamique et des transferts nécessite l’étude des couplages entre convection, diffusion et réaction. Une approche locale à l’échelle de la bulle (simulation directe du transfert réactif et de l’écoulement) est utilisée pour déterminer le transfert interfacial. Des mesures de la propagation de fronts d’oxydation dans la fonte ont permis de préciser certaines propriétés physiques des espèces réactives. L’ensemble de cette analyse multi-échelles a contribué à l’élaboration d’un modèle de simulation d’un nuage de bulles / Many bubbles are generated during glass production. Due to the high viscosity of molten glass, their rising velocity is extremely low. The refining step consists in adding reactive agents to improve the glass quality. Bubble release is enhanced by chemical reaction (iron and sulfate oxidation-reduction) which will favor shrinkage or growth of bubbles through interfacial mass transfer. Better understanding of bubble cloud behavior in molten glass requires studying the interplay between convection, diffusion and chemical reactions. The direct numerical simulation of the flow and reactive mass transfer provided new insights on modeling interfacial bubble gas fluxes. The acceleration factor has been determined for simple reversible reactions in order to validate the simulation tool. Different Péclet and Damkhöler numbers have been tested to map all the different regimes (diffusion, convection and reaction). Together with those simulations, we have carried out series of experiments in molten glass : propagation of oxidation fronts. At different temperatures and for various glass compositions, we have determined physical properties of reactive species. A theoretical model of reactive transport for instantaneous reactions has been proposed to interpret experimental data. The core of this multi-scale analysis contributed to elaborating an Euler- Lagrange model to simulate bubble clouds in reactive media. This model has been applied to specific processes related to glass industry and can easily be extended to any reactive bubbly flows

Dans cette thèse, les propriétés de l'eau en présence d'ions dans des nanoconfinement à base de silice ont été étudiées. L'objectif principal est de relier ces propriétés à l'évolution des matériaux mésoporeux de silice dans les solutions aqueuses. Pour atteindre cet objectif, nous avons utilisé une approche originale consistant à remplir avec des solutions électrolytiques comportant des ions ayant des propriétés kosmotropes différentes, XCl2 (X = Ba, Ca, Mg) des systèmes modèles tels que deux surfaces de silice parallèles et planes espacées de 3 et 5 nm (nanocanaux) et des silices à mesoporosité ordonnée comme les silices SBA-15 (6 nm de taille pores et murs des pores microporeux) et MCM-41 (3 nm de taille de pores et murs des pores denses).Les résultats obtenus indiquent que la cinétique de remplissage des nanocanaux dépend de la taille du confinement, de la nature des ions et de la solubilité des sels associés aux électrolytes. Dans certains cas, le remplissage incomplet des nanocanaux peut s'expliquer par une diminution de la dynamique de l'eau associée à l’atteinte de la saturation vis-à-vis des sels XCl2 dans la couche interfaciale. La possible précipitation de phases XCl2 pourrait permettre d’expliquer le bouchage de certains nanocanaux. Par la suite, les propriétés de l'eau dans des nanoconfinement concave de silice tels que les cylindres ont également été étudiées. La structure de l’eau en présence d’ions et sa dynamique à l’échelle de la picoseconde caractérisées respectivement par FTIR-ATR et diffusion quasi élastique des neutrons, ont été analysées. Les résultats suggèrent que les propriétés structurales et dynamiques de l'eau sont fortement influencées par la taille du confinement, le caractère kosmotrope des ions et l'excès d'ions dans la couche interfaciale.Enfin, nous avons déterminé l’évolution des deux silices mésoporeuses dans des solutions électrolytiques par diffusion des rayons X aux petits angles. Pour une taille de pore de 3 nm et des murs de pores denses (MCM-41), une dynamique de l’eau lente à une échelle picoseconde conduit probablement à une sursaturation des ions dans la couche interfaciale et donc à une reprécipitation des sels XCl2 et / ou de la silice plus stable. Dans ce cas, l'évolution du MCM-41 est induite par un processus de dissolution-recondensation / précipitation. Dans les plus grands mésopores du SBA-15, en raison de la microporosité dans la paroi des pores, le processus d'altération est différent. Dès le début, une couche d'altération se forme et la taille des pores augmente jusqu'à saturation de la silice. Par la suite, un processus de recondensation / précipitation similaire à celui observé dans la MCM-41 se produit dans la microporosité. Ces deux types d'évolutions en silice pourraient persister jusqu'à l'obtention d'une phase de silice thermodynamiquement stable. / In this study, we investigated the water properties in the presence of ions in silica nanoconfinement. The main objective is to relate these water properties to the evolution of silica mesoporous materials in aqueous solutions. To reach this goal, we used an original approach, consisting in the use of electrolyte solutions having ions with various kosmotropic property XCl2 (X = Ba, Ca, Mg) confined in model systems such as two parallel and plane silica surfaces spaced of 3 and 5 nm (nanochannels) and highly ordered mesoporous silica materials represented by SBA-15 (6 nm pore size and microporous pore wall) and MCM-41 (3 nm pore size and dense pore wall).The obtained results indicate that the filling kinetics in nanochannels is driven by the size of the confinement, the nature of ions and the salt solubility of electrolytes. In some cases, the incomplete filling of the nanochannels may be explained by a decrease of water dynamics associated to the saturation of XCl2 salts into the interfacial layer. The possible precipitation of XCl2 phases may explain an incomplete filling by a nanochannels clogging.Thereafter, the water properties in nanoconfinement made of silica concave surface such as cylinders were studied. The water structure and dynamics at a picosecond scale in presence of ions were respecteively characterized by infrared spectroscopy and quasi-elastic neutron scattering. The results suggest that the structural and dynamical water properties are strongly affected by the size of the confinement, the kosmotropic properties of ions and the surface ion excess in the interfacial layer.Finally, we characterized the evolution of the two mesoporous silica in electrolyte solutions using in-situ small-angle X-ray scattering. For 3 nm pore size and dense pore wall (MCM-41), the slow dynamics at a picosecond scale probably lead to a supersaturation of ions in the interfacial layer and thus, to a reprecipitation of XCl2 salts and/or silica phases. In that case, the evolution of the MCM-41 is driven by a dissolution-recondesation/precipitation process. In the bigger mesopores of SBA-15, due to the microporosity in the pore wall, the alteration process is different. During a first stage, an alteration layer is formed and the pore size increases until the silica saturation. Afterwards, a similar recondensation/precipitation process as observed in MCM-41 occurs into the microporosity. These two types silica evolutions could persist until the formation of a thermodynamic stable silica phase.

Neste trabalho, foi estudado o comportamento reológico nos regimes de viscoelasticidade linear (VEL) e não linear (VENL) da mistura polimérica de polimetacrilato de metila/poliestireno (PMMA/PS), compatibilizada ou não com os copolímeros: estatístico P(S-co-MMA) (VEL e VENL) e bloco P(S-b-MMA) (VEL). No estudo do comportamento de VEL, ensaios de cisalhamento oscilatório de pequenas amplitudes (COPA) foram realizados utilizando-se um reômetro de tensão controlada. O comportamento de VEL das misturas poliméricas foi comparado com os modelos teóricos de Bousmina[1] e generalizado de Palierne[2]. Os tempos de relaxação das misturas poliméricas foram obtidos analisando o comportamento reológico no regime de VEL utilizando o software desenvolvido por Honerkamp e Weese[3]. Os tempos obtidos foram comparados com o modelo de Jacobs et al.[4]. O estudo do comportamento de VENL foi conduzido através de ensaios de relaxação de tensão utilizando-se um reômetro de deformação controlada. Os resultados do comportamento reológico no regime de VEL indicaram a presença de quatro tempos de relaxação, para as blendas compatibilizadas com P(S-co- MMA) (composições menores de 10% de fase dispersa e concentrações maiores de 4% de copolímero): dois picos relacionados às fases puras; F, relacionado com a relaxação das gotas da fase dispersa e o relacionado com a relaxação do compatibilizante na interface entre as fases matriz e dispersa. Os valores experimentais de F e foram utilizados para os cálculos de tensão interfacial () e do módulo complexo de interface () das blendas poliméricas compatibilizadas. Os resultados indicaram uma diminuição de com o aumento da concentração de copolímero. Os resultados do comportamento reológico no regime de VEL, para as blendas compatibilizadas com P(S-b-MMA), também apresentaram a presença de quatro tempos de relaxação. Observou-se que o aumento da adição de P(S-b-MMA) proporcionou uma redução no .. Os resultados de VENL de relaxação de tensão mostraram a presença de três fenômenos de relaxação, relacionados com: 1) as fases puras, 2) a relaxação das gotas da fase dispersa e um terceiro mais rápido. A adição de P(S-co-MMA) resultou numa diminuição do processo de relaxação das gotas da fase dispersa. / In this work, the dynamic behavior of polymethylmetacrylate/polystyrene (PMMA/PS) blends to which P(S-co-MMA) was added was studied. Several blend composition and copolymer concentrations were studied. The rheological behavior of blends was compared to Bousminas[1] and Paliernes generalized[2] models. The relaxation spectra of the blends were also inferred, and the results were analyzed in light of the analysis of Jacobs et al.[4]. The relaxation spectra of the blends with smaller dispersed phase (below 10 wt%) and larger copolymer concentrations (above 0.4 wt%) showed the presence of four relaxation times, two corresponding to the blend phases, F, corresponding to the relaxation of the shape of the dispersed phase of the blend, and , that can be attributed to the relaxation of Marangoni stresses tangential to the interface between the dispersed phase and matrix. The experimental values of F and were used to infer the interfacial tension () and the interfacial complex shear modulus () for the different blends, decreased with increasing copolymer concentration. decreased with increasing blend dispersed phase concentration and decreasing copolymer concentration. The predictions of Paliernes generalized model were found to corroborate the experimental data once the values of and found analyzing the relaxation spectra were used in the calculations. Bousminas model was found to corroborate the data only for larger dispersed phase concentration. The stress relaxation behavior of PMMA/PS blends with or without random copolymer addition, submitted to step shear strain experiments in the linear and nonlinear regime was studied. The effect of blend composition, viscosity ratio and random copolymer was evaluated. All blends presented three relaxation stages, a first relaxation which was attributed to the relaxation of the pure phases, a second one which was characterized by the presence of plateau and a third fast one.

A deposição eletroquímica, ou eletrodeposição, é uma técnica amplamente utilizada na obtenção de recobrimentos metálicos. A presença de certos compostos químicos (aditivos) nos banhos eletrolíticos pode influenciar o processo de eletrodeposição de maneira significativa. A glicina é um aminoácido presente em muitos banhos para a eletrodeposição de filmes finos de ligas de cobalto, que são interessantes devido às suas propriedades magnéticas. As propriedades de algumas ligas à base de cobalto obtidas a partir de banhos contendo glicina já foram bem descritas, mas há falta de estudos mais específicos sobre o papel do aminoácido no processo de eletrodeposição do cobalto. Esta Tese apresenta estudos realizados na tentativa de compreender a influência da glicina no mecanismo de eletrodeposição do cobalto. Técnicas de análise in situ, envolvendo espectroscopia no infravermelho por reflexão externa e medidas de pH na região próxima a interface via microeletrodo indicador foram acopladas aos estudos eletroquímicos. Depósitos de cobalto de boa qualidade foram obtidos a partir de banhos contendo glicina, e sob condições de sobrepotencial mais elevadas do que as possíveis para sistemas sem aditivos, onde ocorre precipitação de hidróxidos. Análises dos experimentos de voltametria cíclica indicaram a eletroatividade de complexos cobalto-glicina, e cinética de redução mais lenta foi observada, em relação a sistema sem glicina em valores de pH suficientemente elevados. Os estudos cinéticos foram dificultados pela reação de desprendimento de hidrogênio e a existência de diversos equilíbrios químicos em solução. Durante a eletrodeposição de cobalto em soluções contendo glicina, um aumento bastante significativo no pH próximo da interface foi observado. Os experimentos espectroeletroquímicos também demonstraram deslocamento dos equilíbrios químicos de complexação do cobalto em solução, devido ao aumento do pH interfacial. Todos os estudos mostraram que a presença de glicina favorece a reação de desprendimento de hidrogênio, diminuindo a eficiência de corrente do processo de eletrodeposição. Ainda assim, a glicina se mostrou eficaz na estabilização da solução eletrolítica. / The electrochemical deposition, or electrodeposition, is a widely used technique to obtain metallic coatings. The presence of certain chemical species (additives) in plating baths can significantly influence the metal electrodeposition process. Glycine is an aminoacid present in many electrolytic solutions for electrodeposition of cobalt thin films and alloys, which are interesting due to their magnetic properties. The properties of some Co-based alloys obtained from glycine-containing baths are well documented, but studies of the exact role of the aminoacid are lacking. This Thesis presents studies attempting to understand the influence of glycine on the mechanisms of cobalt electrodeposition. In situ analysis techniques - external reflection FTIR spectroscopy and pH measurement near the electrochemical interface using indicator microelectrodes - were coupled to the electrochemical studies. Good-quality cobalt deposits were obtained from glycine-containing baths, and under higher overpotentials than possible over systems with no additive (in which precipitation of hydroxides occurs). Analysis of the cyclic voltammetry experiments indicated the electroactivity of cobalt-glycine complexes, and the slower reduction kinetics in comparison with glycine-free solutions at sufficiently high pH values. The kinetic studies were hindered by the parallel hydrogen evolution reaction and the existence of several chemical equilibria in solution. During cobalt electrodeposition from glycine-containing solutions, an expressive elevation of the near interface pH was observed. The spectroelectrochemical experiments also showed the displacement of cobalt complexation equilibria in solution, caused by the increase in the interfacial pH. All the conducted studies showed that the presence of glycine favors the hydrogen evolution reaction, decreasing the current efficiency for the electrodeposition process. Nevertheless, glycine was able to stabilize the electrolyte solution.