The processing and properties of novel polymer-based nano-composite (PNC) dielectrics for capacitor applications has been studied. PNCs were fabricated via a vacuum based deposition technique and their micro/nano-structure, chemical and dielectric properties investigated. After process development and optimisation, co-deposited Al and nylon-6 PNCs had a dielectric constant k∼7 at an approximate Al volume fraction of 0.3 that agreed with analytical predictions if it was assumed that the Al transformed to an oxide in-situ and/or after deposition. The significant effect of absorbed water vapour and temperature on PNC dielectric properties was revealed using different types of post-deposition heat treatment. Alternately-deposited PNCs consisting of Al or Ag 2-20 nm layers sandwiched between nylon-6 layers were fabricated in which the overall PNC Al or Ag volume fraction was controlled by varying the nominal Al or Ag layer thickness. Ag layers comprised of discrete nano-islands that produced a nano-capacitor network effect that increased k to ∼11. In the case of Al layers, when the layer thickness was ≥ 5 nm, corresponding to a nominal volume fraction of 0.1, Al (core)-oxide (shell) nanoparticles were formed and the PNC dielectric constant increased to ∼19. The detailed nano-structure of the core-shell particles was studied using various types of transmission electron microscopy (TEM), and the elevations in dielectric constant ascribed to multiple-interface polarisation effects dependent on the formation of the core-shell structure. PNCs based on alternate deposition of Ti sandwiched in nylon-6, and then both Ti and Ag in nylon-6 were also fabricated, with k reaching ∼73 for Ag+Ti/nylon-6 PNCs. As well as Ti-based core (metal)-shell (oxide) particles, the Ag volume fraction was sufficiently high in the 10 nm nylon-6 layers to again form a nano-capacitor network that contributed to the overall device capacitance and effective dielectric constant. Again, various types of high magnification TEM were critical in resolving the Ti-based core-shell structure and its role in high-k behaviour. The vacuum-based alternate deposition technique has been developed to offer ease of operation, reliability, flexibility and applicability to chemically different filler and matrix systems in the fabrication of high-k PNC based capacitors, in which high-k performance relies critically on the formation of core (metal)-shell (oxide) particles in both Al and Ti based systems.

Multi-walled carbon nanotubes (MWCNTs) were successfully coated with two different pseudocapacitive polyoxometalates (POMs) (SiMo12O40-4 (SiMo12) and PMo12O40-3 (PMo12)) via “Layer-by-Layer” deposition. Even with merely a “single-layer” of POM, the modified nanotubes exhibited more than 2X increase in capacitance compared with that of bare nanotubes. To further improve their electrochemical performances, the deposition sequence of the POM layers was adjusted to form “alternate layer” coating to modify MWCNT. A synergistic effect on the capacitance and kinetics was observed with the alternate layer coatings. X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM) also proved the successful coating of POMs on MWCNTs. The potential-pH relationship provided important insights in terms of the deposition mechanism and suggested that the bottom layer close to the electrode substrate was the dominating layer in alternate layer coated MWCNT electrodes.

Multi-walled carbon nanotubes (MWCNTs) were successfully coated with two different pseudocapacitive polyoxometalates (POMs) (SiMo12O40-4 (SiMo12) and PMo12O40-3 (PMo12)) via “Layer-by-Layer” deposition. Even with merely a “single-layer” of POM, the modified nanotubes exhibited more than 2X increase in capacitance compared with that of bare nanotubes. To further improve their electrochemical performances, the deposition sequence of the POM layers was adjusted to form “alternate layer” coating to modify MWCNT. A synergistic effect on the capacitance and kinetics was observed with the alternate layer coatings. X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM) also proved the successful coating of POMs on MWCNTs. The potential-pH relationship provided important insights in terms of the deposition mechanism and suggested that the bottom layer close to the electrode substrate was the dominating layer in alternate layer coated MWCNT electrodes.

Orientadores: Miriam Dupas Hubinger, Vanessa Martins da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-22T08:01:27Z (GMT). No. of bitstreams: 1 Carvalho_AnaGabrieladaSilva_M.pdf: 18654651 bytes, checksum: b9cbc1f805b1d0974af4067819e06088 (MD5) Previous issue date: 2013 / Resumo: O óleo de café verde merece destaque na área cosmética por sua capacidade de bloquear a radiação solar UVB (290-320 nm) e por suas propriedades emolientes. Nesse contexto, para melhor aproveitar as propriedades desse óleo e aumentar a sua estabilidade oxidativa, pretendeu-se com este trabalho produzir micropartículas de óleo de café verde, pelo processo físico de spray drying. Como agentes encapsulantes foram utilizados lecitina, um fosfolipídeo de caráter aniônico quando em pH 3,0, quitosana, um polissacarídeo de caráter catiônico também em pH 3,0 e solúvel somente em sistemas ácidos diluídos, além de sólidos de xarope de milho ou amidos modificados derivados do milho, HiCap 100 e Snow-Flake. O preparo das emulsões foi feito através da técnica de estabilização por atração eletrostática de cargas opostas entre a lecitina e a quitosana. Com o propósito de se obter emulsões com dupla camada estáveis à separação de fase, foi utilizado um rotor-estator e um homogeneizador a alta pressão. As emulsões foram analisadas quanto à estabilidade, distribuição de tamanho e diâmetro médio das gotas, microscopia ótica, potencial zeta e comportamento reológico. As emulsões preparadas com Snow-Flake e xarope de milho/Snow-Flake (50/50) apresentaram comportamento pseudoplástico, além de apresentarem os maiores diâmetros de gota variando de 3,70 a 5,19 µm. Contudo, as emulsões com xarope de milho, HiCap 100 e xarope de milho/HiCap 100 (50/50) apresentaram comportamento de fluidos Newtonianos e diâmetros menores de gota, entre 1,15 e 1,51 µm. Para o processo de secagem foi utilizado um secador laboratorial do tipo mini spray dryer, com temperatura do ar de secagem de 170 °C. As micropartículas obtidas foram caracterizadas em relação ao conteúdo de umidade, atividade de água, distribuição de tamanho e diâmetro médio de partículas e microestrutura. Além disso, foram também determinados: a eficiência de encapsulação, o fator de proteção solar in vitro das micropartículas e estabilidade oxidativa pelo método Rancimat. As micropartículas apresentaram diâmetro entre 14,51 e 29,19 µm e excelentes valores de eficiência de encapsulação, superiores a 84%. As partículas produzidas com os amidos modificados apresentaram formato esférico sem rachaduras ou poros, já as micropartículas produzidas com somente xarope de milho apresentaram alguns poros e rachaduras, que causaram a menor estabilidade oxidativa dessas micropartículas. As micropartículas produzidas com HiCap 100 e xarope de milho/HiCap 100 (50/50) estabilizadas por lecitina-quitosana apresentaram maior estabilidade oxidativa. O fator de proteção das partículas variou entre 1,37 e 2,45, sendo de 2,12 para o óleo de café verde puro / Abstract: The green coffee oil stands out for its ability to block the UVB radiation (290-320 nm) and its emollient property. In this context, to improve the properties of this oil and increase its stability, the aim of this work was to produce microparticles of green coffee oil by spray drying. Encapsulating agents used were lecithin, a phospholipid with anionic character at pH 3.0, chitosan, a polysaccharide with cationic character also in pH 3.0 and soluble only in diluted acid solutions and corn syrup solids or corn modified starches as HiCap 100 and Snow-Flake. Emulsions preparation involved the technique of stabilization by electrostatic attraction between lecithin and chitosan. A rotor-stator homogenizer and a high pressure homogenizer were used in order to obtain stable emulsions by electrostatic layer-by-layer deposition. The emulsions were analyzed in relation to stability, size distribution and droplet diameter, optical microscopy, zeta potential and rheological behavior. The emulsions prepared with Snow-Flake and corn syrup/Snow-Flake (50/50) showed pseudoplastic behavior, besides having the biggest droplet diameters ranging from 3.70 to 5.19 µm. However emulsions prepared with corn syrup, HiCap 100 and corn syrup/HiCap 100 (50/50) showed Newtonian behavior and smaller droplet diameters ranging from 1.15 to 1.51 µm. For the drying process, a laboratory spray dryer and air temperature of 170 °C were used. Microparticles were characterized with respect to moisture content, water activity, particle size distribution and microstructure. Furthermore, encapsulation efficiency, sun protection factor in vitro and oxidative stability by the Rancimat method were determined. The microparticles had a diameter ranging from 14.51 and 29.19 µm and high values of encapsulation efficiency, above 84%. The particles produced with modified starches showed spherical shape without cracks or pores and those produced with only corn syrup showed some holes and cracks, that caused lower oxidative stability of these microparticles. The microparticles produced with HiCap 100 and corn syrup/HiCap 100 (50/50) stabilized by lecithin-chitosan showed the highest oxidative stability. The sun protection factor of particles ranged from 1.37 and 2.45 and 2.12 for the pure green coffee oil / Mestrado / Engenharia de Alimentos / Mestra em Engenharia de Alimentos

Layer-by-layer deposition techniques were used to fabricate films with second order nonlinear optical (NLO) properties. These materials are key to the development of electro-optic modulators used in fiber optic communication systems. Performance benefits and lower manufacturing costs are driving the development of organic NLO materials as replacements for inorganic crystalline materials such as lithium niobate. The layer-by-layer deposition technique in which polyelectrolytes are deposited on a surface by electrostatic effects is called the Ionically Self-Assembled Monolayer or ISAM method. The role of the optically inactive polycation's structure on deposition and chromophore orientation was studied by fabricating films with several different polycations. While the specific interactions responsible for chromophore orientation in ISAM films remains unclear, hydrogen bonding and electrostatic effects are ruled out as the sole sources of orientation. The highest values of χ(2) were observed under pH conditions that resulted in flat and thin layers. The relationship between pH and the optical homogeneity of the film was also explored. Deposition of polymers under pH conditions in which the polymer chains were aggregated in solution results in films that are not suitable for use in devices. In this work, a new layer-by-layer deposition technique was developed. Coined hybrid deposition, it relies on covalent bonds and electrostatic interactions for film fabrication. Optically inactive polyamines were used as sources of positive charges and as binding sites with optically active low molecular weight chromophores functionalized with a reactive triazine ring and negative charged sulfonate groups. Polar ordering of the chromophores was obtained when the deposition was done under conditions in which covalent bonding was the preferred attachment mechanism for the chromophore molecules. pH conditions in which electrostatic attachment dominated resulted in poorer orientation. The effect of adding ionic salts to the dye solutions was studied, with hopes of increasing the chromophore density in the film by shielding inter-dye electrostatic repulsions. A linear relationship in deposited amount, as characterized by absorbance/bilayer, was observed as the salt concentration was increased. Little effect on χ;(2) was observed for films made with the as-received Procion Red MX-5B chromophore. However, films fabricated from purified Procion Brown MX-GRN showed a definite dependence on added salt. Exceptional χ(2) values were obtained for Procion Brown films deposited using 0.5 M NaCl and PAH. The importance of depositing from non-aggregated solutions was again highlighted, as films made with the less soluble Procion Orange were significantly less homogeneous than those made from Procion Red and Procion Brown which were highly soluble. The role of polycation structure on the deposition and orientation of Procion Brown and Red was examined. / Ph. D.

Orientadores: Ana Flávia Nogueira, Valtencir Zucolotto / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-22T02:59:18Z (GMT). No. of bitstreams: 1 Almeida_LuizCarlosPimentel_D.pdf: 6880507 bytes, checksum: f7a2c24853f25411226ae9b66a2de97b (MD5) Previous issue date: 2012 / Resumo: Neste trabalho foram estudados filmes finos multicamadas baseados em polímeros condutores, nanotubos de carbono e um derivado de fulereno. Esses filmes foram depositados pela técnica de deposição camada por camada (LbL) via interações eletrostáticas. Esse trabalho está dividido em duas partes: 1-) Filmes LbL baseados no polímero conjugado poli(p-fenilenovinileno) (PPV) e nanotubos de carbono de parede única funcionalizados com grupos carboxílicos (SWNTCOOH) foram preparados em arquitetura de bloco, caracterizados e aplicados como fotoeletrodos em células solares fotoeletroquímicas. A morfologia desses filmes foi avaliada por microscopia de força atômica (AFM) e de epifluorescência, as quais indicaram uma variação morfológica significativa dos filmes após adição de camadas de nanotubos de carbono. A transferência de carga fotoinduzida do polímero condutor PPV para o SWNT-COOH foi analisada por supressão de fotoluminescência (PL). A caracterização fotoeletroquímica foi realizada sob irradiação de luz branca e os fotoeletrodos contendo SWNT-COOH apresentaram valores de fotocorrente de até 7,5 mA cm. A fotocorrente aumentou e tornou-se mais estável quando uma camada do polímero poli(3,4-etilenodioxitiofeno) dopado com poli(4-sulfonato de estireno) (PEDOT:PSS) foi depositada entre o eletrodo ITO e o filme LbL. 2-) Foram preparados filmes LbL baseados no polímero conjugado poli[2-(3-tienil)-etoxi-4-butilsulfonato] de sódio (PTEBS) e no derivado de fulereno C60-F. A caracterizacao fotofísica mostrou a ocorrência de transferência fotoinduzida de carga do PTEBS para o C60-F, a qual foi também demonstrada por meio da geração de fotocorrente obtida quando os filmes (PTEBS/C60-F) foram aplicados como fotoeletrodos em células solares fotoeletroquímicas. Os resultados obtidos fazem dos filmes LbL baseados em semicondutores orgânicos candidatos promissores para conversão de energia solar. / Abstract: In this work, multilayer thin films based on conducting polymers, carbon nanotubes and fullerene derivatives were studied. These films were fabricated by layer-by-layer deposition technique (LbL) through electrostatic interactions. This work is divided in two parts: 1-) LbL films composed of a conducting polymer poly(p-phenylenevinylene) (PPV) and carboxylic acid functionalized singlewalled carbon nanotubes (SWNT-COOH) were prepared in a block architecture, characterized and applied as electrodes in photoelectrochemical solar cells. Film morphology was evaluated by atomic force and epifluorescence microscopies, showing remarkable changes after incorporation of SWNT-COOH layers. The photoinduced charge transfer from the conducting polymer to SWNT-COOH was analyzed by photoluminescence (PL) quenching. Photoelectrochemical characterization was performed under white light and the films containing SWNTCOOH displayed photocurrent values up to 7.5 mA cm. Photocurrent generation was enhanced and became more stable when an intermediate layer of poly(3,4- ethylenedioxythiophene)¿poly(4-styrenesulfonic acid) (PEDOT:PSS) was interposed between the ITO electrode and LbL films. 2-) LbL films based on the conducting polymer sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate] (PTEBS) and fullerene derivative C60-F were fabricated. Photophysical characterization shows the occurrence of photoinduced charge transfer from PTEBS to C60-F, which was also demonstrated by photocurrent generation obtained when (PTEBS/C60-F) multilayer films were applied as electrodes of photoelectrochemical solar cells. All these results make the LbL films based on organic semiconductors promising canditates towards solar energy conversion. / Doutorado / Físico-Química / Doutor em Ciências

Orientador: Varlei Rodrigues / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-31T16:45:14Z (GMT). No. of bitstreams: 1 Ferreira_RafaelCintraHensel_M.pdf: 43759995 bytes, checksum: 8636f117e63053d6b540d65b95c34072 (MD5) Previous issue date: 2016 / Resumo: Os filmes orgânicos ultrafinos tem permitido funcionalizar superfícies a fim de introduzir propriedades específicas que diferem daquelas apresentadas em escala macroscópica. Um processo versátil para modificar superfícies e criar sistemas multifuncionais é a técnica de automontagem por adsorção física (LbL, do inglês Layer-by-Layer), na qual nanoestruturas são formadas devido a adsorção de moléculas com cargas opostas em arquiteturas moleculares multicamadas. O monitoramento elétrico do crescimento dos filmes é essencial em experimentos nos quais não são permitidas caracterizações ópticas. Além disto, é importante compreender as propriedades elétricas destes filmes devido a sua utilização em sensores capacitivos para análise química. Deste modo, neste trabalho desenvolvemos um equipamento capaz de acompanhar o crescimento de filmes LbL por meio de medidas de capacitância após a deposição de cada camada de polieletrólitos sobre eletrodos interdigitados (IDEs, do inglês Interdigitated Electrodes). Observamos um aumento linear da capacitância devido ao acúmulo de material dielétrico sobre os IDEs, com uma alternância na medida de capacitância de acordo com o polieletrólito depositado, isto é, há uma reversão de carga na camada mais externa quando a adsorção do policátion é compensada pela do poliânion, ou vice-versa. Utilizando o modelo para o potencial eletrostático de um IDE proposto por M. W. Den Otter, desenvolvemos uma nova metodologia para investigar a constante dielétrica da estrutura multicamadas formada. Obtivemos (16 ± 1) para a constante dielétrica do filme LbL (PDDA/CuTsPc), e (21 ± 3) para a arquitetura (PDDA/PSS), ambos em satisfatória concordância com a literatura. Ademais, desenvolvemos um modelo para interpretar o deslocamento na capacitância medida após a adsorção do policátion a fim de determinar sua densidade de carga superficial, que diminuiu de (0,23 ± 0,02) e/µm2 para (0,08 ± 0,01) e/µm2 quando o PDDA (policátion fortemente carregado) foi substituído pelo PAH (policátion fracamente carregado) para ambos os poliânions analisados. Portanto, desenvolvemos um equipamento para monitorar o crescimento de filmes LbL e uma metodologia que permite obter informações sobre o comportamento dielétrico dos filmes a cada camada depositada, o que pode auxiliar na escolha dos materiais e espessura dos filmes LbL utilizados como elementos transdutores em desenvolvimentos futuros / Abstract: Organic ultrathin films have enabled surface¿s functionalization in order to introduce specific properties which differ from those in macroscopic scale. A versatile process to modify surfaces and create multifunctional systems is the layer-by-layer (LbL) technique, in which the nanostructures are formed due to the adsorption of charged molecules in multilayered molecular architectures. The electrical monitoring of the film's growth is essential in experiments in which optical characterizations can not be used. Moreover, it is important to comprehend the electrical properties of these films owing to their application on capacitive sensors for chemical analysis. In this research we developed a home-made setup to keep track of the LbL film¿s growth by measuring the capacitance after each deposited layer onto interdigitated electrodes (IDEs). We have observed a linear increase in the capacitance due to accumulated dielectric material onto the IDEs, along with an alternation in the measured capacitance according to the deposited polyelectrolyte, i.e., a charge reversal of the outermost layer as the polycation adsorption is compensated by the polyanion adsorption, or vice-versa. Using the IDEs electrostatic potential model proposed by M. W. Den Otter, we have developed a new methodology to investigate the dielectric constant of the formed multilayered structure. A dielectric constant of (16 ± 1) was obtained for (PDDA/CuTsPc) films and (21 ± 3) for (PDDA/PSS) architecture, both in satisfactory agreement with the literature. Furthermore, we have developed a model to interpret the capacitance measurement shift after the polycation adsoption in order to investigate its surface charge density, which decreased from (0.23 ± 0.02) e/µm2 to (0.08 ± 0.01) e/µm2 when PDDA (strong polycation) was replaced by PAH (weak polycation) for both analyzed polyanions. Therefore, we have developed an equipment to monitor the LbL film's growth as well as a methodology that enables the obtaining of information about the film dielectric behavior at each deposited layer, which can assist in the choice of the materials and thickness of the LbL films that are used as transductor elements in future developments / Mestrado / Física / Mestre em Física / 147530/2014 / CNPQ

The cellular response to a biomaterial, such as a dental implant, is mainly governed by the surface properties, and can thus be altered by the introduction of a surface coating. In this thesis the buildup of a biomacromolecule-based coating formed by layerby-layer (LbL) deposition of the charged polypeptides poly(L-lysine) (PLL) and poly(L-glutamic acid) (PGA) has been studied. In an attempt to make these coatings bioactive and useful for bone-anchored implants, an amelogenin protein mixture (EMD), has been immobilized in these thin polyelectrolyte multilayer (PEM) films. Multilayers were also built by LbL deposition of the natural biomacromolecules collagen (Col) and hyaluronic acid (HA). Multilayer films of these two extra-cellular biomacromolecules should be of interest for use as a scaffold for tissue engineering. The buildup of the multilayer films has been followed in situ, using ellipsometry, quartz crystal microbalance with dissipation (QCM-D), and dual polarization interferometry (DPI). The studied PLL/PGA multilayers were found to be highly hydrated, and to exhibit a two-regime buildup behavior, with an initial “slow-growing” regime, and a second “fast-growing” regime with a linear growth in film thickness and more than linear growth in mass. A net diffusion of polypeptides into the film during the buildup led to an increase in density of the films for each layer adsorbed. A change in density was also observed in the Col/HA film, where HA penetrated and diffused into the porous fibrous Col network. The formed PLL/PGA films were further found to be rather stable during drying, and post-buildup changes in temperature and pH, not losing any mass as long as the temperature was not raised too rapidly. The film thickness responded to changes in the ambient media and collapsed reversibly when dried. A swelling/de-swelling behavior of the film was also observed for changes in the temperature and pH. The EMD protein adsorbed to silica surfaces as nanospheres, and could by itself form multilayers. The adsorption of EMD onto PLL/PGA multilayer films increased at lower pH (5.0), and EMD could be immobilized in several layers by alternate deposition of EMD and PGA. / QC 20101019

<p>The cellular response to a biomaterial, such as a dental implant, is mainly governed by the surface properties, and can thus be altered by the introduction of a surface coating. In this thesis the buildup of a biomacromolecule-based coating formed by layerby-layer (LbL) deposition of the charged polypeptides poly(L-lysine) (PLL) and poly(L-glutamic acid) (PGA) has been studied. In an attempt to make these coatings bioactive and useful for bone-anchored implants, an amelogenin protein mixture (EMD), has been immobilized in these thin polyelectrolyte multilayer (PEM) films. Multilayers were also built by LbL deposition of the natural biomacromolecules collagen (Col) and hyaluronic acid (HA). Multilayer films of these two extra-cellular biomacromolecules should be of interest for use as a scaffold for tissue engineering.</p><p>The buildup of the multilayer films has been followed in situ, using ellipsometry, quartz crystal microbalance with dissipation (QCM-D), and dual polarization interferometry (DPI). The studied PLL/PGA multilayers were found to be highly hydrated, and to exhibit a two-regime buildup behavior, with an initial “slow-growing” regime, and a second “fast-growing” regime with a linear growth in film thickness and more than linear growth in mass. A net diffusion of polypeptides into the film during the buildup led to an increase in density of the films for each layer adsorbed. A change in density was also observed in the Col/HA film, where HA penetrated and diffused into the porous fibrous Col network.</p><p>The formed PLL/PGA films were further found to be rather stable during drying, and post-buildup changes in temperature and pH, not losing any mass as long as the temperature was not raised too rapidly. The film thickness responded to changes in the ambient media and collapsed reversibly when dried. A swelling/de-swelling behavior of the film was also observed for changes in the temperature and pH.</p><p>The EMD protein adsorbed to silica surfaces as nanospheres, and could by itself form multilayers. The adsorption of EMD onto PLL/PGA multilayer films increased at lower pH (5.0), and EMD could be immobilized in several layers by alternate deposition of EMD and PGA.</p>

L’objectif de cette étude a été de formuler et caractériser des émulsions simples huile/eau d’intérêt pharmaceutique stabilisées par de la β-lactoglobuline (β-lg), de la gomme arabique (GA), de la gomme xanthane (GX) et des mélanges β-lg:GA et β-lg:GX. Les concentrations massiques totales des dispersions de biopolymères étaient de 1 % et ont été augmentées à 2,5 % si les émulsions formulées n’étaient pas stables. Le mélange β-lg:GA a été réalisé à pH 4,2 afin de permettre la formation de complexes par interactions électrostatiques attractives entre la β-lg et la GA. Deux ratios β-lg:GA ont été étudiés : 2:1 et 1:2. Enfin, le mélange β-lg:GX a été effectué à pH 7, où les deux biopolymères étant chargés négativement ne se complexent pas et à un ratio de 1:1. Une étude de stabilité des émulsions a été menée sur 6 mois. Les stabilités obtenues ont pu être classées par ordre croissant : GA 2,5 % < β-lg:GA 2,5 % < β-lg 2,5 % < GX 1 % = β-lg:GX 1 %. Plusieurs mécanismes de stabilisation ont été mis en évidence grâce à l’étude des propriétés interfaciales des biopolymères, à l’étude des propriétés rhéologiques des émulsions et à des observations au microscope confocal à balayage laser des émulsions après marquage des biopolymères à la fluorescence. La β-lg et la GA sont toutes deux capables de s’adsorber à l’interface des globules huileux alors que la GX augmente la viscosité de la phase continue. L’association β-lg:GA conduit à la formation d’une double couche interfaciale stabilisante. Enfin, l’association β-lg:GX combine les mécanismes de stabilisation de la protéine, par adsorption interfaciale et de la gomme, par augmentation de la viscosité de la phase continue. / The main objective of this study was to formulate and characterize oil-in-water simple emulsions of pharmaceutical interest stabilized by β-lactoglobulin (β-lg), gum arabic (GA), xanthan gum (XG), and mixtures of β-lg:GA and β-lg:XG. The total biopolymer final concentration in the dispersions was 1 (w/w) % and could be raised to 2.5 (w/w) % if the formulated emulsions were not stable. β-lg:GA mixing was performed at pH 4.2 to allow attractive electrostatic interactions between the two biopolymers and thus the formation of complexes. Two protein:polysaccharide ratios were investigated: 2:1 and 1:2. Conversely, β8lg:XG mixing was performed at pH 7, where both biopolymers are negatively charged, in order to avoid the complex formation, and with a 1:1 ratio. A stability study was conducted for emulsions over a 6-month period. The obtained stabilities could be classified increasingly: GA 2.5 % < β-lg:GA 2.5 % < β-lg 2.5 % < XG 1 % = β-lg:XG 1 %. Several stabilization mechanisms were evidenced by the study of the biopolymer interfacial properties, the study of emulsion rheology and by confocal laser scanning microscopy observations with labeled fluorescent biopolymers. β-lg and GA were both able to adsorb at the interface of oil globule. XG enhanced the continuous phase viscosity. β-lg:GA mixing led to the formation of a stabilizing interfacial double layer. Finally, β-lg:XG association combined the stabilization mechanisms of both biopolymers, respectively: interfacial adsorption and enhancement of the continuous phase viscosity.