<p>Metal-organic frameworks (MOFs) are considered as a type of very useful materials for the gas separation/purification industries. However, control over the growing position and growing shape of the crystals remains a challenge and must be overcome in order to realize the commercial potentials of MOFs.</p> <p>In this thesis, a method based on interfacial coordination is developed to address this issue. Zinc-benzenedicarboxyl (Zn-BDC) is chosen as a model system for the proof of concept. In a typical liquid-liquid interface protocol, the MOF precursors, zinc nitrate [Zn(NO3)2] and terephthalic acid (TPA or H2BDC), and the catalyst, triethylamine (TEA), were dissolved into two immiscible solvents, dimethylformamide (DMF) and hexane, respectively. The reaction site, i.e. the MOF growing position could thereby be confined at the interface of the two solvents. It was found that a free-standing membrane could be formed with the combinations of high Zn-H2BDC and low TEA concentrations. The combinations of low Zn-H2BDC and high TEA concentrations yielded MOF particles precipitated out from DMF. Similar results were obtained by changing the liquid-liquid interface to liquid-gas interface, with the TEA-hexane solution replaced by saturated TEA vapor. The dependence of product shape on precursor and catalyst concentrations can be explained by the competition between MOF formation and TEA diffusion into the precursor phase.</p> <p>The morphology, constitution and surface area of the MOF products were characterized by SEM, XRD and nitrogen adsorption testing, respectively. The particles were found to be exclusively MOF-5. The membranes were characterized as asymmetric. The top layer was particulate while the bottom layer had a sheet-like morphology. This was further revealed by XRD data as MOF-5 and MOF-2 (ZnBDC·DMF), respectively. This asymmetry was caused by a change of TEA diffusion rate during the synthesis process, which might result in a change in pH value for the membrane growth. Decent surface areas of the particles and membranes were measured.</p> <p>Apart from the free-standing membranes, MOF membranes on Anodisc support were also synthesized employing the same interfacial techniques. The MOF formation site, i.e. the interface, was confined to the upper end Anodisc pores and sealing the pores after the reaction. The difference in wetting force between DMF and hexane with Anodisc membrane material resulted in the difference of MOF layer morphology from liquid-liquid protocol and liquid-gas protocol. The later gave a continuous MOF membrane due to the absence of air bubble interference.</p> / Master of Science (MSc)

No / This study investigates the interfacial characteristics between aggregates and cement paste matrix in nanofillers modified concrete. A three-point bend test on the specimens composed of two pieces of aggregates bonded with a thin layer of cement pastes with/without nanofillers was carried out to characterize the interfacial bond strength of the composites. The scanning electron microscope observations and energy dispersive x-ray spectrometry analysis were also performed to characterize the interfacial microstructures and compositions of the composites. The experimental results indicated that the nanocomposites have higher interfacial bond strength and narrower interfacial transition zone thickness as well as more optimized intrinsic compositions and microstructures than that of composites without nanofillers. Specifically, the interfacial bond strength of nanocomposites can reach 7.67 MPa, which is 3.03 MPa/65.3% higher than that of composites without nanofillers. The interfacial transition zone thickness of nanocomposites ranges from 9 μm to 12 μm, while that of composites without nanofillers is about 18 μm. The ratio of CaO to SiO2 in the interface of composites without nanofillers is 0.69, and that of nanocomposites increases to 0.75–1.12. Meanwhile, the nanofiller content in nanocomposite interface is 1.65–1.98 times more than that in the bulk matrix. The interfacial microstructures of nanocomposites are more compact and the content and crystal size of calcium hydroxide were significantly reduced compared with that of composites without nanofillers. / National Science Foundation of China (51978127 and 51908103), and the China Postdoctoral Science Foundation (2019M651116).

Surface tension is an essential force for the functioning of the world and life. Centuries of study, and still, new applications and limits of surface tension are being explored. Water has always drawn attention for its high surface tension value, 72mN/m compared to ethanol's 20mN/m. The high surface tension allows for numerous applications, superhydrophobic surfaces being one that takes heavy advantage of that value. Superhydrophobicsurfaceshave a high surface energy cost with water, resulting in small contact areas with high advancing and receding contact angles and low contact angle hysteresis. This results in very low adhesion on the surfaces. Here we study the ability of superhydrophobic surfaces with their low adhesion to shed meltwater from frost, showing a decrease in frost thickness to below 3mm for the meltwater to shed. We then take another approach to removing water from a surface, rather than increasing the surface energy cost, we introduce a difference in surface energy cost. Introducing a porous surface across from a solid one, droplets transfer from the solid to the porous, removing over 90% of the volume of the droplet from the solid surface. We thoroughly examine and model the hydrodynamics of the transfer process, varying the solid surface, the donor surface, and the liquid. This bridging between surfaces is then applied to fog harps, examining the efficiencies of large-form fog harps. Fog harps have shown a 3 to 5 times increase in water collection compared to the industry-standard mesh collector. However, droplets from fog collected on the wires eventually grow large enough to touch neighboring wires. Tominimizetheirsurfaceenergy, they begin pulling wires together, "tangling" them. This can potentially reduce efficiency, but has not been applied to large-scale harps until here. Another application of surface tension is then examined, using lower surface tension oils, but trapping them in microstructures to make slippery liquid-infused porous surfaces (SLIPS). The oil coats the microstructure, due to its lower surface tension. This creates a lubricating layer on the surface, along with potential air pockets reducing friction further. These surfaces have been studied extensively with liquids being placed on them, but here we begin to examine them when solids are used instead, showing some interesting cases where increasing the viscosity of the oil actually decreases the friction force. / Doctor of Philosophy / Sponges are something everyone has used, and most people can tell you that they work using surface tension. And for most people, that's enough. It's actually more useful to know to squeeze your sponge dry when you're done to prevent mold than it is to know that it holds onto liquids because of surface tension. But the point here was to take the study of sponges and surface tension to the extreme. To the point that some knowledge is going to be gained solely for the sake of gaining knowledge. Not all knowledge will have immediate uses, but this doesn't take value away from the knowledge, or any eventual uses it might have. So we start this by looking at the building of scientific knowledge and noticing that a brick is missing. Superhydrophobic surfaces, surfaces that water doesn't want to touch, have been studied very extensively and their properties have been thoroughly explored. However, a direct comparison of the defrosting behaviors, the process of frost melting on a surface, between superhydrophobic and hydrophobic surfaces had not been done. Water does prefer to be on a hydrophobic surface compared to a superhydrophobic one, but it's still uncomfortable. A plate was treated so that half was hydrophobic and the other half was superhydrophobic. Frost was grown across the surface and then melted simultaneously, allowing us to characterize the differences in the behaviors, highlighting the ability of the superhydrophobic surface to shed water droplets at smaller sizes than other surfaces. Next is a pure fluid mechanics work supporting a heat transfer application. Evaporation, for enhanced heat transfer, and a hydrophilic wick, essentially a sponge, are paired to create a plate with one-way heat transfer. Heating side A can heat side B, but heating side B can't heat side A. Water in the wick gets heated, evaporates from side A and then condenses on side B, carrying heat with it. The condensation grows until it touches the wick, which then pulls it in, allowing it to be evaporated again and cycling more heat. When side B, the smooth surface, is heated, the water can evaporate off it and condense in the wick, but then it has no way to return, preventing further heat transfer. The process of droplets being pulled from side B to the wick in side A is key to the process. It's a sponge pulling water in using surface tension. However, all the smaller pieces have been taken for granted. The second piece is a systematic study of this capture mechanism, exploring the effects of changing liquids, donor surfaces, and receiving porous wicks. The third is a continuation of the lab's previous work on Fog Harps, arrays of vertical fibers held in place to let fog run into them. The droplets grow until they slide down and can be collected. The wires of the harp are close enough that the water can actually start to tangle them together. This tangling can increase the water needed for sliding and collection to begin. Tensioning the wires can help mitigate the tangling. Here we show harps on around 1,$text{m}^2$, using optimal wire size and spacing that is possible for mass manufacturing. The harps were tested in the lab using humidifiers to generate fog for the harps to collect. Finally, an initial study of solid objects being pulled across oil-infused microstructured surfaces. The microstructure helps keep the oil on the surface thanks to the surface energy of the oil. These oil-infused surfaces have been studied extensively when liquids are placed on them, but not with solid objects. Solid objects can exert significantly more pressure than liquids, which naturally want to spread when they reach a certain thickness. Experiments were performed with a variety of oil viscosities, microstructures, and oil excess thicknesses. This work is not entirely complete but a significant portion of it is presented here.

We developed a quantitative measurement technique using atomic force microscopy (AFM) to study the effects of both DC and AC external electric fields on the forces between two dielectric microspheres. In this work we measured the DC and AC electric field-induced forces and adhesion force between two barium titanate (BaTiO?) glass microspheres in a low humidity environment by this technique. The objective here is to find out the correlation between these measured forces and applied field strength, frequency, and the separation distance between the two spheres was studied. Since the spheres would oscillate under an AC field, the AC field-induced force was divided into dynamic component (i.e., time-varying term) and static component (i.e., time-averaged term) to investigate. The oscillatory response occurs at a frequency that is twice the drive frequency since the field-induced force is theoretically proportional to the square of the applied field. This behavior can be observed in the fast Fourier transformation (FFT) spectra of the time series of the deflection signal. The magnitude of the vibration response increases when the frequency of the drive force is near resonant frequency of the particle-cantilever probe. The amplitude of this vibration increases with proximity of the two particles, and ultimately causes the particles to repeatedly hit each other as in tapping mode AFM. The effect of the Maxwell-Wagner interfacial relaxation on the DC electric field-induced force was discovered by monitoring the variation of the field-induced force with time. The static component of the AC electric field-induced force does not vary with the applied frequency in the range from 1 to 100 kHz, suggesting that the crossover frequency may equal to or less than 1 kHz and the permittivities of the BaTiO? glass microspheres and medium dominate the field-3 induced force. The AC field-induced force is proportional to the square of the applied electric field strength. This relationship persists even when the separation between the spheres is much smaller than the diameter of the microspheres. The large magnitude of the force at small separations suggests that the local field is distorted by the presence of a second particle, and the continued dependence on the square of the field but the measured force is much larger than the theoretical results, suggesting that the local electric field around the closely spaced spheres is distorted and enhanced but the effects of the local field distortion may have not much to with the applied electric field. Compared with the calculated results from different models, our results demonstrate that the field-induced force is much more long-range than expected in theory. In addition, the DC field-induced adhesion force is larger than the AC field-induced one due to the interfacial charge accumulation, agreeing with the discovery of the Maxwell-Wagner interfacial relaxation effect on the DC field-induced force. No obvious correlation between the field-induced adhesion and the applied frequency is found. However, both the DC and AC field-induced adhesion forces display the linearity with the square of the applied electric field strength as well. / Master of Science

An experimental investigation was undertaken to analyze the behavior of sandwich composite structures exposed to one-sided heating where a debond exists between the unexposed facesheet and core material. Sandwich composites of plain weave E-glass/epoxy facesheets and an end-grain balsa wood core manufactured using the Vacuum Assisted Resin Transfer Molding (VARTM) technique were the only materials analyzed. These were selected due to their current use in naval vessels and the heightened interest in the fire response properties of balsa wood and its utility as a core material. In order to better understand the interfacial behavior, Mode I Double Cantilever Beam (DCB) fracture tests were performed at ambient, 60 C, and 80 C to determine the influence of the decreased Mode I fracture toughness. While ambient testing showed that stable crack growth could be obtained, high temperature tests resulted in considerable damage occurring to the core at the crack-front preventing stable crack growth. This can be attributed to the significant decrease in the balsa core strength and material properties even for small increases in temperature. Additionally, Mode II Cracked Split Beam (CSB) tests were performed at ambient temperature to examine the sliding dominant crack-growth. Again, the occurrence of balsa core damage prevented stable crack-growth and an accurate measurement of Mode II fracture toughness was not obtained. Intermediate-scale compression testing with one-sided heating at two heat flux levels was performed with a custom designed load frame on sandwich composite columns. This enabled the influence of the debond to be measured using a 3D-Digital Image Correlation (DIC) technique spatially linked with a thermographic camera. The DIC allowed for a detailed observation of debond growth and buckling prior to global failure of the test article. A behavior similar to that observed in the Mode I DCB fracture tests occurred: as the interfacial temperature increased, the amount of crack growth decreased. This crack growth was followed by a core failure at the crack-front, triggering a global failure of the test article. This global failure for test articles containing a debond manifested itself primarily as an anti-symmetric post-buckling shape. Test articles with no debond exhibited the typical progression of the out-of-plane displacement profile for a fixed-fixed column. As the out-of-plane displacement increased, core failure ultimately occurred near the gripped region where the zero-slope condition is required, triggering global failure of the no debond test article. These tests highlight that the reduction in strength and material properties of the end-grain balsa wood core significantly outweigh the reduction in interfacial fracture toughness due to the increased temperatures. / Master of Science

In this study, a test technique, referred to as the probe test, has been developed as a quantitative tool for measuring the adhesion in thin adhesive films and coatings. The technique was initially developed as a qualitative test by the Hewlett-Packard Company for measuring adhesion of thin film microelectronic coatings. In the probe test method, an inclined needle-like probe with a conical tip is advanced underneath the free edge of a thin polymeric coating bonded to a substrate, causing the edge to lift-up from the surface of the substrate. A debond is thus initiated at the loading point and propagates as a semi-circular crack at the interface as the probe slides under the coating. A standard test procedure has been developed for testing thin adhesive coating/substrate systems. The sample system used is a thin film epoxy polymer coated silicon system. The interfacial fracture energy (Gc) (or critical strain energy release rate) has been used as a quantitative measure of adhesion for the given adhesive coating/substrate system. The probe test experiments were conducted using an optical microscope and a WYKO optical profiler. Using the optical microscope, the debond radius was measured for different debond sizes. Using the WYKO optical profiler, the three-dimensional surface topography of the debonded coating around the crack front was measured for different debond sizes. Using the experimental data from the probe test, analytical and numerical (finite element-based) techniques have been developed to determine the interfacial fracture energy (Gc) for the given adhesive coating/substrate system. The analytical techniques were developed based on different plate theory formulations (thin/thick plate - small/large deflection) of the probe test geometry and local curvature measurement at the crack tip. The finite element based techniques were developed using a hybrid numerical-experimental approach and surface-based contact interaction analysis in ABAQUS. The results obtained using thick plate-large deflection formulation correlated with finite element contact interaction analysis results. The probe test can be used with transparent or opaque coatings and thus offers a promising alternative to indentation and other tests methods for characterizing thin film and coating adhesion. / Master of Science

Les effets du caoutchouc nitrile (NBR), du traitement de la surface des fibres et du noir de carbone sur les propriétés des composites à base de caoutchouc naturel renforcé par des fibres d'ananas (NR / PALF) ont été étudiés. L'incorporation de NBR et le traitement de surface de la fibre ont été utilisés pour améliorer les propriétés mécaniques des composites à faible déformation, alors que le noir de carbone a été utilisé pour améliorer ces propriétés à forte déformation. La teneur en fibres a été fixée à 10 phr. Les matériaux composites ont été préparés à l'aide d'un mélangeur à cylindres et ont été réticulés sous presse permettant ainsi le maintien de l'orientation des fibres. Ces composites ont été caractérisés à l’aide du rhéomètre à matrice mobile (MDR), par analyse thermique mécanique dynamique (DMTA) et par tests de traction. La morphologie après fracture cryogénique a été observée à l'aide de la microscopie électronique à balayage (MEB). L'effet du NBR dont la teneur varie de 0 à 20 phr par rapport à la teneur totale en caoutchouc, a été également étudié. Le NBR est utilisé afin d’encapsuler totalement les fibres d’ananas (PALF) ; ceci conduisant à un meilleur transfert de contraintes entre la matrice et les fibres. La méthode de mélange a également été étudiée. Plusieurs types de silanes tels que le propylsilane, l'allylsilane et le silane-69 ont été utilisés pour traiter les fibres pré-nettoyées à l’aide d’un traitement alcalin. Les fibres silanisées ont été caractérisées par spectroscopie infrarouge à transformée de Fourier (FTIR), par spectroscopie de photoélectrons aux rayons X (XPS) et par MEB. Le traitement de la fibre par le silane-69 a permis d’augmenter fortement le module du matériau composite à faible déformation. Ce traitement a été plus efficace que l'incorporation de NBR dans les composites NR / PALF. Ceci peut s’expliquer par une possible réticulation chimique entre le caoutchouc et la fibre traitée au silane-69 plutôt qu’une simple interaction physique du NR, du NBR et de la fibre. Cependant, le renforcement par fibre réduit la déformation à la rupture. Par conséquent, du noir de carbone a également été incorporé dans les composites NR/NBR/PALF et NR/ PALF traitée, afin d’améliorer leurs propriétés ultimes. En incorporant du noir de carbone à un taux de 30 phr dans les deux composites, les propriétés mécaniques des composites ont été améliorées et peuvent être contrôlées à la fois à des déformations faibles et hautes. / The effects of nitrile rubber (NBR), fiber surface treatment and carbon black on properties of pineapple leaf fiber-reinforced natural rubber composites (NR/PALF) were studied. The incorporation of NBR and surface treatment of fiber were used to improve the mechanical properties of composites at low deformation, whereas carbon black was used to improve these properties at high deformation. The fiber content was fixed at 10 phr. The composites were prepared using two-roll mill and were cured using compression moulding with keeping the fiber orientation. These composites were characterized using moving die rheometer (MDR), dynamic mechanical thermal analysis (DMTA) and tensile testing. The morphology after cryogenic fracture was observed using scanning electron microscopy (SEM). The effect of NBR from 0 to 20 phr of total rubber content was investigated. NBR is proposed to encase PALF leading to higher stress transfer between matrix and PALF. The method of mixing was also studied. For the fiber surface treatment, propylsilane, allylsilane and silane-69 were treated on the alkali-treated fiber. Treated fibers were characterized using Fourier-Transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS) and SEM. Silane-69 treatment of fiber increased the modulus at low deformation more than the incorporation of NBR of NR/PALF composites due to the chemical crosslinking between rubber and fiber from silane-69 treatment rather than the physical interaction of NR, NBR and fiber. However, reinforcement by fiber reduced the deformation at break. Hence, carbon black was also incorporated into NR/NBR/PALF and NR/surface-treated PALF composites to improve the ultimate properties. By incorporation of carbon black 30 phr in both composites, the mechanical properties of composites were improved and can be controlled at both low and high deformations.

Dióxido de carbono supercrítico (scCO2) é um solvente pouco eficiente para substâncias polares em geral. Uma maneira interessante de superar esta limitação e explorar todo o seu potencial como solvente verde, possível substituto para os solventes orgânicos voláteis comuns, é a introdução de tensoativos específicos para scCO2 no sistema. No presente trabalho, foram sintetizadas três novas séries de tensoativos oxigenados para scCO2. As moléculas possuem cabeças CO2-fóbicas mono e poli-hidroxiladas, em sua maioria à base de açúcares, e três tipos de cadeias CO2-fílicas, duas delas perfluoradas (-C7F15 e -C9F19) e uma peracetilada (derivada do ácido D-glucônico). Foram investigadas as suas solubilidades e comportamentos de fase em CO2 e em sistemas ternários (água-CO2-tensoativo), bem como a atividade na interface CO2-água. Todos eles dispersaram água em scCO2 com [água] / [tensoativo] (W) igual a 10, exibindo pressões de névoa comparáveis àquelas do sistema \"a seco\". Adicionalmente, os tensoativos reduziram a tensão interfacial CO2-água. O efeito das cabeças CO2-fóbicas e cadeias CO2-fílicas nessa redução pôde ser analisado separadamente. Os resultados dos experimentos de tensão interfacial dinâmica sugerem que tanto a difusão das moléculas da fase contínua para a subinterface, quanto a sua inserção e migração na interface contribuem para o decaimento das tensões interfaciais. / Supercritical carbon dioxide (scCO2) is a poor solvent for polar substances in general. An interesting way to overcome this limitation and fulfill its potential as a green solvent, a possible substitute for common volatile organic solvents, is the introduction of scCO2-suitable surfactants in the system. In the present work, three series of novel oxygenated surfactants for scCO2 were synthesized. The amphiphiles contain mono and poly-hydroxylated CO2-phobic heads, most of them sugar-based, as well as three types of CO2-philic tails, two of them perfluorinated (-C7F15 and -C9F19) and one peracetylated (D-gluconic acid derivative). Their solubilities and phase behaviors in CO2 and in ternary systems (water-CO2-surfactant), as well as their activities at the CO2-water interface, were investigated. All of them dispersed water in scCO2- with water-to-surfactant ratio (W) of 10, exhibiting cloud pressures comparable to those of \"dry\" systems. Also, the surfactants reduced the CO2-water interfacial tension. The effect of both the CO2-phobic heads and the CO2-philic tails could be analyzed separately. Dynamic interfacial tension results suggest that both diffusion from bulk CO2 to subinterface and insertion and migration of molecules within the interface contribute to the time-dependent decay of the interfacial tensions.

Investigou-se o efeito do \"caráter iônico\" de interfaces zwitteriônicas, formalmente neutras, representadas por micelas e vesículas obtidas de monômeros com cabeça hidrofílica dipolar, nas propriedades de acumulação e troca de espécies iônicas. Os sistemas estudados incluíram, micelas de 1-(N-hexadecil-N,N-dimetilamônio) propanossulfonato (HPS), Hexadecil fosforil colina (C16PN), 3-hexadecil glicerofostidil colina (lisoPC) e vesículas de fosfatidil colina (PC). O estudo da ligação e troca iônica nestas interfaces foi monitorado a partir de efeitos sobre reações prototrópicas de sondas como a 8-hidroxi-1,3,6-pirenotrisulfonato de sódio (piranina). Observou-se a ligação crescente da piranina na seguinte ordem lisoPC < C16PN < HPS e troca iônica com sais adicionados (função do ânion) na ordem inversa, isto é, lisoPC &gt; C16PN &gt; HPS. Estudos de reprotonação de 1 e 2 naftóis incluídos nestes agregados, via salto de pH induzido por laser, revelaram um perfil de concentração de prótons inverso àquele das cargas do dipolo, isto é, concentração nos polos negativos e exclusão nos positivos. Este resultados foram ainda reforçados por estudos de excitação de volume, via espalhamento de luz, com micelas de HPS em função de sal adicionado. A partir destes resultados propôs-se um modelo de capacitor esférico imerso em meio eletrolítico para estas interfaces, o qual se mostrou bastante versátil na análise e previsão de resultados experimentais. Em suma, estabeleceu-se no presente trabalho a visão de que interfaces dipolares são geradoras de assimetria iônica na circunvizinhança da interface, assimetria esta de polaridade invertida àquela do dipolo radialmente disposto à interface. A generalidade deste modelo pode ser extrapolado para outras interfaces e colaborar na compreensão de diversos processos que dependem da acumulação e troca iônica. / The effect of ionic domains of formally neutral zwitterionic interfaces, represented by micelles and vesicles obtained with dipolar headgroups amphiphiles, on the binding and exchange of ionic species were investigated. The systems studied included: aqueous micelles of 1-(N-hexadecyl-N,N-dimethylammonio) Propane Sulfonate (HPS), Hexadecyl Phosphoryl Choline (C16PN), and 1-hexadecylglycerophostidyl Choline (lisoPC) and vesicles of Phosphatidylcholine (PC). Binding and ion-exchange processes were assessed from the effect of these agreggates on prototropic reactions of probes such as 8-hydroxy-1,3,6-pyrenetrisulfonate pyranine). Binding of pyranine increased in the following order lisoPC < C16PN < HPS. The effectiveness of anion dependent salt displacement of the probe from the aggregates was opposite to that of affinities, i.e. lisoPC &gt; C16PN &gt; HPS. Laser pH jump studies with 1 and 2 naphtols incorporated in these aggregates revealed a proton concentration profile inverse to that of the charged dipole, that is, accumulation in the region vicinal to the negatively charged group and exclusion from the positive end of the dipole. This finding were substantiated by HPS micelle excluded volume data, obtained from light scattering studies as function of added salt. A model of a spherical capacitor immersed in an electrolyte media for these interfaces was proposed. This model accounts for satisfactorily the observed characteristics of these interfaces. The model establishes that dipolar interfaces generate ionic asymmetries in the neighborhood of the interface that opposes the radially extended monomer dipole. The generality of the model can be very helpful in the analysis and understanding of several processes occurring in/at zwitterionic interfaces.

Dióxido de carbono supercrítico (scCO2) é um solvente pouco eficiente para substâncias polares em geral. Uma maneira interessante de superar esta limitação e explorar todo o seu potencial como solvente verde, possível substituto para os solventes orgânicos voláteis comuns, é a introdução de tensoativos específicos para scCO2 no sistema. No presente trabalho, foram sintetizadas três novas séries de tensoativos oxigenados para scCO2. As moléculas possuem cabeças CO2-fóbicas mono e poli-hidroxiladas, em sua maioria à base de açúcares, e três tipos de cadeias CO2-fílicas, duas delas perfluoradas (-C7F15 e -C9F19) e uma peracetilada (derivada do ácido D-glucônico). Foram investigadas as suas solubilidades e comportamentos de fase em CO2 e em sistemas ternários (água-CO2-tensoativo), bem como a atividade na interface CO2-água. Todos eles dispersaram água em scCO2 com [água] / [tensoativo] (W) igual a 10, exibindo pressões de névoa comparáveis àquelas do sistema \"a seco\". Adicionalmente, os tensoativos reduziram a tensão interfacial CO2-água. O efeito das cabeças CO2-fóbicas e cadeias CO2-fílicas nessa redução pôde ser analisado separadamente. Os resultados dos experimentos de tensão interfacial dinâmica sugerem que tanto a difusão das moléculas da fase contínua para a subinterface, quanto a sua inserção e migração na interface contribuem para o decaimento das tensões interfaciais. / Supercritical carbon dioxide (scCO2) is a poor solvent for polar substances in general. An interesting way to overcome this limitation and fulfill its potential as a green solvent, a possible substitute for common volatile organic solvents, is the introduction of scCO2-suitable surfactants in the system. In the present work, three series of novel oxygenated surfactants for scCO2 were synthesized. The amphiphiles contain mono and poly-hydroxylated CO2-phobic heads, most of them sugar-based, as well as three types of CO2-philic tails, two of them perfluorinated (-C7F15 and -C9F19) and one peracetylated (D-gluconic acid derivative). Their solubilities and phase behaviors in CO2 and in ternary systems (water-CO2-surfactant), as well as their activities at the CO2-water interface, were investigated. All of them dispersed water in scCO2- with water-to-surfactant ratio (W) of 10, exhibiting cloud pressures comparable to those of \"dry\" systems. Also, the surfactants reduced the CO2-water interfacial tension. The effect of both the CO2-phobic heads and the CO2-philic tails could be analyzed separately. Dynamic interfacial tension results suggest that both diffusion from bulk CO2 to subinterface and insertion and migration of molecules within the interface contribute to the time-dependent decay of the interfacial tensions.