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Gauthier, Anaïs. "Hydrophobie dynamique et Dynamiques hydrophobes." Palaiseau, Ecole polytechnique, 2015. https://tel.archives-ouvertes.fr/tel-01236723/document.
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This work focuses on situations in which movement and liquid repellency are combined. First, we study dynamic hydrophobicity, a phenomenon created by the horizontal movement of a flat surface, here a rotating plate of bare aluminum. When the surface reaches a critical velocity, approaching droplets cannot penetrate the boundary layer of air that covers the surface, thus protected from wetting. Droplets that are gently deposited on the substrate levitate a few micrometers above the surface, while falling droplets can bounce off, much faster than in other non-wetting situations. If the plate moves fast enough, all liquids can be repelled, creating an omniphobic surface. In a second part, we investigate the dynamics of drops in contact with surfaces textured at a microscopic scale, which makes them water-repellent. We show that viscous drops deposited on a moving superhydrophobic surface are not immediately carried away, but accelerate and start to spin very rapidly. As the substrate velocity increases, the spinning makes the drops loose their spherical shape and turn into bilobes, and sometimes trilobes. We also study the impact of water droplets on superhydrophobic surfaces macrotextured by a straight wire or a marble of same repellency, with a typical size of 100 mm. The bouncing dynamics are dramatically modified in presence of the macrotexture : on a wire drops take-off as 1, 2 or 4 independent sub-units while in presence of a marble they exhibit surprising doughnut shapes. This affects the contact time, which takes discrete values with increasing impact velocity. At high velocity it is divided by a factor of 2 compared to a non-textured surface, which enhances anti-icing properties.
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Motornov, Mikhail. "Herstellung und Untersuchung schaltbarer Polymerschichten mit hydrophobem, hydrophilem Charakter (Fabrication and study of switchable polymerlayers with hydrophobic, hydrophilic behavior) /." [S.l. : s.n.], 2004. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11513723.
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Rocco, Caroline. "Polymérisation sous rayonnement UV et lumière naturelle de réseaux de polymères interpénétrés pour des revêtements auto-régénérants." Thesis, Mulhouse, 2015. http://www.theses.fr/2015MULH8175.
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Les réseaux de polymères interpénétrés (IPNs) combinent les propriétés de leurs différents composants. Ils possèdent une bonne résistance thermique, mécanique et chimique, et s’avèrent très intéressants pour pallier les inconvénients des réseaux homopolymères. Une méthode de synthèse rapide et efficace fait appel à la photopolymérisation. Les IPNs photopolymérisés sont donc très attractifs pour l’obtention de revêtements industriels présentant des propriétés de surface avancées. Cette thèse porte sur la réalisation de revêtements hydrophobes présentant des propriétés d’auto-régénération suite à un endommagement. Le concept mis en œuvre repose sur la ségrégation vers la surface de groupements fonctionnels liés chimiquement à un réseau IPN photopolymère, par différence de tension superficielle entre la surface et l’intérieur du matériau. L’auto-régénération de la fonctionnalité de surface nécessite une distribution homogène et une mobilité suffisante des groupements fonctionnels dans la matrice polymère. Des surfaces auto-régénérantes basées sur un réseau acrylate photopolymérisé ont d’abord été développées afin de démontrer la faisabilité du concept. Des IPNs photopolymérisés sous lumière UV et naturelle, combinant deux polymères (acrylates et époxydes) possédant des Tgs faibles et élevées (auto-régénération combinée avec résistance mécanique), et présentant des morphologies différentes ont ensuite été étudiés. Des surfaces auto-régénérantes possédant une Tg plus élevée compatible avec des applications industrielles ont été obtenuesInterpenetrating polymer networks (IPNs) combine properties of their different components. They exhibit high mechanical strength, good thermal stability and chemical resistance. They are thus interesting to overcome the limitations of stand-alone networks. One of the easy and efficient ways to produce IPNs involves light curing. Considering these features, photocured IPNs are very attractive materials for functional polymeric surfaces in the coating industry. This thesis reports the development of hydrophobic coatings showing self-replenishing properties upon surface damage. This concept relies on the segregation of functional groups chemically bound to a light-cured IPN network towards the surface, thanks to the energy difference between surface and bulk. Surface functionality self-repairing mechanism requires a homogeneous distribution and a sufficient mobility of functional groups in the polymeric network. Self-replenishing hydrophobic surfaces based on a UV-cured acrylate network have been firstly developed in order to demonstrate the proof of concept. In a second part, UV and visible-light cured IPNs combining two polymers (acrylates and epoxides) with low and high Tgs (self-replenishing together with mechanical resistance), showing different morphologies have been investigated. Finally, self-replenishing hydrophobic surfaces with enhanced Tg more suitable for industrial applications have been obtained
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Le, Tuan Khanh. "Hydrophobic Cluster analysis : prédiction de structures secondaires à partir d'une séquence unique : implémentation de la procédure "Secondary Structure Prediction" (SSP)." Paris 6, 2003. http://www.theses.fr/2003PA066541.
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Rossignol, Cindie. "Couplage d'un contacteur membranaire à extraction liquide-liquide avec un biorécteur pour la production de molécules hydrophobes par voie biotechnologique." Thesis, Clermont-Ferrand 2, 2013. http://www.theses.fr/2013CLF22353.
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Le travail présenté porte sur le couplage d’un procédé membranaire à extraction liquide-liquide avec un bioréacteur impliquant des molécules hydrophobes. La bioconversion modèle utilisée est la production de cis-2-methyl-5-isopropylhexa-2,5-dienal (isonovalal) à partir d’α-pinène oxyde, instable en phase aqueuse, par des cellules entières perméabilisées de Pseudomonas rhodesiae (CIP 107491). La production d’isonovalal en milieu biphasique eau (tampon phosphate)/hexadécane présente des verrous technologiques importants, dont une inactivation de l'enzyme à l'interface eau-solvant organique ainsi que l'apparition d'une émulsion stable. L’intérêt de la membrane porte sur l'absence de formation d'émulsion et sur l’augmentation de la durée de vie du biocatalyseur en raison de l'absence de contact direct du biocatalyseur avec l'interface liquide-liquide. La nature de la membrane a été choisie à partir de l'analyse des propriétés physico-chimiques du matériau et de l’étude des affinités entre membrane et composés d’intérêt (solutés, solvants). Il a été montré que les conditions d'écoulement au voisinage de la membrane, notamment du côté aqueux, jouent un rôle prépondérant sur les vitesses de transfert. Ce résultat souligne l'importance du design et des conditions d'opération du module membranaire sur les capacités de transfert. Le couplage de l’extraction membranaire liquide-liquide et de la réaction biologique a conduit à la mise en place d’un système bi-membranaire. Le prototype développé a permis de doubler les capacités catalytiques (+ 100 % d’isonovalal par gramme de biomasse) ainsi que de la durée de vie du biocatalyseur (160 h contre 80 h) par rapport à la même bioconversion réalisée en système biphasique conventionnelThe study deals with the combination of a membrane process based on liquid/liquid extraction with a bioreactor producing hydrophobic molecules. The bioconversion used is the production of cis-2-methyl-5-isopropylhexa-2,5-dienal (isonovalal) from α-pinene oxide (unstable in aqueous phase) by whole cells of Pseudomonas rhodesiae (CIP 107491). The production of isonovalal in two-phase medium water/organic is known about but presents important technological brakes. Membrane interest concerns the stabilization of liquid/liquid interface and capacity to increase the biocatalyst life-time. Membrane nature is chosen from the analysis of physical and chemical properties of membrane material and study of the affinities between membrane and interest compounds (solutes, solvents). Two membrane contactors are designed and implemented on laboratory scale to study transfers between liquid phases. It is shown that the hydrodynamic conditions in the membrane neighborhood, in particular on aqueous side, play a major role on transfer speeds. This result underlines the importance of design and operation conditions in membrane module about the transfer capacities. The combination of liquid/liquid membrane extraction and biological reaction with unstable substrate had been studied and lead to the implementation of a serial bi-membrane system. The developed prototype, equipped with a PTFE membrane (polytetrafluoroethylene) with 0.22 μm pores’ diameter, highlights a doubling of catalytic capacities (+ 100 % of isonovalal per gram of biomass) as well as biocatalyst life-time (160 hours against 80 hours) compared with the same bioconversion realized in conventional two-phase medium system
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Albenge, Olivier. "Phénoménologie de l'hydrophobie : essuyabiltié d'un pare-brise hydrophobe." Toulouse 3, 2003. http://www.theses.fr/2003TOU30057.
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Brussieux, Charles. "Cellules électrochimiques produisant du gaz : suivi de l'électrolyse par émission acoustique et effets de la mouillabilité des électrodes sur le flux des charges électriques." Phd thesis, Ecole Centrale Paris, 2011. http://tel.archives-ouvertes.fr/tel-00647080.
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Certains procédés d'électrolyse industriels, comme ceux de production de fluor et d'aluminium, génèrent du gaz sur des électrodes peu mouillées par l'électrolyte. Dans ces procédés, la convection est en grande partie induite par le mouvement des bulles. Le temps de résidence du gaz n'étant pas maitrisé, la modélisation de ces électrolyses se heurte à de nombreux défis. Ce travail propose un état des connaissances nécessaires à la modélisation de ce type de cellules. Après avoir mis au point une méthode permettant de réaliser des électrodes fortement hydrophobes, nous avons étudié le dégagement gazeux que celles-ci produisent. Nous avons observé que les bulles qui s'y forment croissent par coalescence et ce phénomène affecte la vitesse de croissance et la taille au détachement. Par la suite, nous avons démontré qu'en localisant le dépôt hydrophobe il est possible d'obtenir une population de bulles dont le nombre, la taille et la position sont maitrisés. Nous avons constaté que l'émission acoustique est un outil efficace pour mesurer, sans observation visuelle, la taille et la vitesse d'ascension des bulles produites par électrolyse. La fréquence la plus énergétique du spectre des salves d'émission acoustique des cellules d'électrolyse produisant du gaz permet, quand la fraction volumique de gaz est faible, de mesurer la taille de toutes les bulles dans la cellule. Quand les bulles sont nombreuses et denses, cette même fréquence est liée aux dimensions de la cellule, à la densité de courant, à la taille des bulles et à la fraction volumique en gaz dans le panache. Nous avons proposé une explication à cette observation basée sur l'hypothèse d'un couplage acoustique des bulles. En l'absence d'agitation vigoureuse, l'activité acoustique d'une cellule d'électrolyse produisant des bulles traduit l'importance du transport de matière aux électrodes. La mesure de la répartition de la densité de courant par la méthode des électrodes segmentées dans une cellule en convection libre a été réalisée. Cette étude a été menée dans le but de tester un outil de simulation numérique des cellules d'électrolyse produisant du gaz. L'effet de la mouillabilité de l'électrode sur la répartition du courant a été évalué.
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Cui, Di. "Synthèse et caractérisation de capsules multicouches fonctionnelles à base de polysaccharides modifiés." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00621208.
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This work focused on the design of functional capsules made of chemically modified polysaccharides. The layer-by-layer capsules have attracted great interest due to their Indeed, as an advanced multifunctionality which can be advantageously used for pharmaceutical and biomedical applications. Polysaccharides, which are generally biocompatible and biodegradable, are very attractive materials for the construction of bio-related multilayer systems. Considering the intrinsic antibacterial properties of chitosan (CHI), this polysaccharide was selected and quaternized to prepare in physiological conditions contact-killing capsules by combination with hyaluronic acid (HA). The relationship between the antibacterial activity of the quaternized chitosan derivatives (QCHI) and that of QCHI-based capsules was investigated. Then, in order to encapsulate small hydrophobic drugs within the wall of capsules, alkylated derivatives of HA were used as the negatively charged partner of QCHI for the capsules formation. The encapsulation of the hydrophobic dye, nile red (NR), in the hydrophobic shell of capsules was determined. At last, to release the payload under mild conditions was studied by synthesizing rapidly degradable capsules composed of hydrolysable cationic dextran derivatives and HA. The degradation of the layer-by-layer assemblies, both multilayer films and microcapsules is discussed.
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Soisson, Arnaud. "Développement de polymères hydrophobes résistants à haute température pour l’encapsulation de module de puissance." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLV024.
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L’objectif de cette thèse était de concevoir denouveaux matériaux polymères hydrophobes pour la protectionde composants semi-conducteurs, résistants à hautetempérature, aux forts champs électriques et aux atmosphèresagressives. Dans ce contexte, les polyimides d’addition sontapparus comme la famille de polymères la mieux adaptée pourl’application envisagée. La synthèse de l’encapsulant étantréalisée directement dans les boîtiers des modules, elle ne peutdonc pas contenir de solvant organique exogène. Ainsi, nousavons développé de nouvelles voies de synthèse sans solvantde poly(aminobismaléimide)s et de poly(bismaléimide)s.Dans un premier temps, différentes diamines aliphatiques ontété utilisées comme solvant réactif lors de la synthèse depoly(aminobismaléimide)s à une température bien inférieure à latempérature de fusion du bismaléimide utilisé (Tf > 300 °C). Unepremière série de 3 nouveaux poly(aminobismaléimide)sréticulés de 70 à 95 % a ainsi été réalisée. A partir de cespremières synthèses, 10 nouveaux poly(aminobismaléimide)sont été élaborés. Pour 9 d’entre eux, des diamines aromatiquesont été utilisées et, pour le dernier, une diamine siloxane. Cesrésultats démontrent la possibilité de généraliser ce procédé desynthèse.Dans un second temps, des poly(bismaléimide)s ont étésynthétisés, toujours sans solvant. Pour cela, les synthèses dequatre nouveaux bismaléimides liquides à température ambianteont été mises au point. Ces composés ont une structurealiphatique ou siloxane dans laquelle un motif pyroméllitique aété, ou pas, introduit. Leur polymérisation amorcée avecl’amorceur radicalaire ad hoc, conduit à la formation desmatériaux sans l’usage de solvant.Selon le choix des réactifs, des matériaux thermodurcissablesou élastomères sont obtenus. Ces derniers semblent mieuxadaptés à l’application souhaitée car, d’une part, la faibleviscosité des mélanges réactionnels permet leur applicationsans difficulté dans un module de puissance et, d’autre part, leurcaractère hydrophobe est plus marqué. L’un d’eux présente unestabilité thermique à 250 °C particulièrement intéressante et unetempérature de relaxation mécanique quasi hors gamme detempérature de fonctionnement. Ce matériau peut doncvraisemblablement être utilisé comme encapsulantThe aim of this work is to develop new hydrophobicpolymeric materials for the protection of semi-conductorcomponents. These materials must withstand high temperature,strong electric fields and aggressive atmospheres such asmoisture. In this context, addition polyimides emerged as themost suitable polymers for the intended application. Thesynthesis of the encapsulant being made directly in the powermodules, it must be solvent free. Thus, we have developed newsolvent free synthesis routes of poly(aminobismaleimide)s andpoly(bismaleimide)s.First of all, different aliphatic diamines were used as a reactivesolvent in the synthesis of poly(aminobismaleimide)s to atemperature well below the melting point of the usedbismaleimide (m.p. > 300 °C). A first series of 3 newpoly(aminobismaleimide)s, crosslinked from 70 to 95 %, hasthus been made. From these first syntheses, 10 newpoly(aminobismaleimide)s have been developed. For 9 of them,aromatic diamines were used and, for the latter, a siloxanediamine. These results demonstrate that this process can begeneralized.Secondly, poly(bismaleimide)s were synthesized, still withoutany solvent. In order to do so, the syntheses of four newbismaleimides, liquid at room temperature, have beendeveloped. These compounds have an aliphatic or siloxanestructure in which a pyromellitic pattern has been or notintroduced. Their polymerization initiated with the suitable radicalinitiator leads to the formation of materials without the use of anysolvent.Depending on the choice of reagents, thermosetting materials orelastomers are obtained. These latter seem more suitable for thedesired application because, on one hand, the low viscosity ofthe reaction mixtures enables their application in a powermodule without any difficulty and, on the other hand, theirhydrophobic behaviour is stronger. One of them has aparticularly attractive thermal stability at 250 ° C and amechanical relaxation temperature almost out of the workingtemperature range. Therefore, this material may be used asencapsulant
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Mancera, Ricardo Luis. "Understanding the hydrophobic effect." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627110.
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Pazhianur, Rajesh R. "Hydrophobic Forces in Flotation." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/28066.
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An atomic force microscope (AFM) has been used to conduct force measurements to better understand the role of hydrophobic forces in flotation. The force measurements were conducted between a flat mineral substrate and a hydrophobic glass sphere in aqueous solutions. It is assumed that the hydrophobic glass sphere may simulate the behavior of air bubbles during flotation. The results may provide information relevant to the bubble-particle interactions occurring during flotation. The glass sphere was hydrophobized by octadecyltrichlorosilane so that its water contact angle was 109 degrees. The mineral systems studied include covellite (CuS), sphalerite (ZnS) and hornblende (Ca₂(Mg, Fe)₅(Si₈O₂₂)(OH,F)₂). The collector used for all the mineral systems studied was potassium ethyl xanthate (KEX).
For the covellite-xanthate system, a biopotentiostat was used in conjunction with the AFM to control the potential of the mineral surface during force measurements. This was necessary since the adsorption of xanthate is strongly dependent on the electrochemical potential (Eₕ) across the solid/liquid interface. The results show the presence of strong hydrophobic forces not accounted for by the DLVO (named after Derjaguin, Landau, Verwey and Overbeek) theory. Furthermore, the potential at which the strongest hydrophobic force was measured corresponds to the potential where the flotation recovery of covellite reaches a maximum, indicating a close relationship between the two.
Direct force measurements were also conducted to study the mechanism of copper-activation of sphalerite. The force measurements conducted with unactivated sphalerite in 10⁻³ M KEX solutions did not show the presence of hydrophobic force while the results obtained with copper-activated sphalerite at pH 9.2 and 4.6 showed strong hydrophobic forces. However, at pH 6.8, no hydrophobic forces were observed, which explains why the flotation of sphalerite is depressed in the neutral pH regime.
Direct force measurements were also conducted using hornblende in xanthate solutions to study the mechanism of inadvertent activation and flotation of rock minerals. The results show the presence of long-range hydrophobic forces when hornblende was activated by heavy metal cations such as Cu²⁺ and Ni²⁺ ions. The strong hydrophobic forces were observed at pHs above the precipitation pH of the activating cation. These results were confirmed by the XPS analysis of the activated hornblende samples.
Force measurements were conducted between silanated silica surfaces to explore the relationship between hydrophobicity, advancing contact angle (CA), and the magnitude (K) of hydrophobic force. In general, K increases as Contact Angle increases and does so abruptly at Contact Angle=90°. At the same time, the acid-base component of the surface free energy decreases with increasing CA and K. At CA>90°, GammaSAB approaches zero.
Based on the results obtained in the present work a mathematical model for the origin of the hydrophobic force has been developed. It is based on the premise that hydrophobic force originates from the attraction between large dipoles on two opposing surfaces. The model has been used successfully to fit the measured hydrophobic forces using dipole moment as the only adjustable parameter. However, the hydrophobic forces measured at CA>90° cannot be fitted to the model, indicating that there may be an additional mechanism, possibly cavitation, contributing to the appearance of the long-range hydrophobic force.Ph. D.
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Oliveira, Adauê Siegert de. "Efeito de cobertura antiaderente no acúmulo de biofilme em dispositivos ortodônticos." Universidade Federal de Pelotas, 2012. http://repositorio.ufpel.edu.br/handle/ri/2218.
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Previous issue date: 2012-06-01The use of orthodontic devices has been associated with an increase in dental biofilm retention. In this study, the effect of hydrophobic coatings, based on (fluorinated or not) organo-silanes, on the reduction of the contact angle and early biofilm retention in orthodontic devices was tested. Two different types of hydrophobic were tested: hydrophobic solution 1 (SH1), obtained by dilution of 2.5% of hexadecyl-triethoxy-silane in ethanol, and hydrophobic solution 2 (SH2), composed of 2.5% of perfluorodecyl-triethoxy-silane diluted in dimethyl sulfoxide. The solutions were applied in ceramic and stainless steel substrates and, via sol-gel process and crosslinking, siloxane networks were formed on the surface of the devices. The effect of the coatings was evaluated in two stages. In the first stage, aiming the characterization of the surface, the water contact angle was analyzed. Stainless steel and polycrystalline alumina plates were prepared, previously applying or not alumina sandblasting as surface treatment. A significant increase in contact angle was observed with the application of both hydrophobic solutions in both substrates, with the sandblasting allowing formation of super-hydrophobic surface in the ceramic substrate (contact angle up to 155o), while hydrophobic surfaces were obtained in the steel substrate (contact angle up to 123o). In the second phase, the effect of the hydrophobic coating on the biofilm retention in orthodontic brackets was evaluated using a microscosm model. Orthodontic brackets were previously prepared according to the surface treatments that showed the best results in the phase 1 (SH1 for steel, SH2 for ceramic). The effect of the coatings on the biofilm formation was evaluated in periods of 12h and 24h (controls: uncoated substrates and sandblasted substrates). The results showed that the hydrophobic coatings did not result in significant effect in biofilm retention for the time 12h, whereas all coating treatments significantly reduced the biofilm retention in the metal and ceramic brackets compared with the control groups. A significant exponential reduction in biofilm retention at 24h was associated with the increase in contact angle. It can be concluded that application of (super)-hydrophobic crosslinked coatings via sol-gel process on the surface of orthodontic metal and ceramic brackets reduced the surface wetting of the surfaces in contact with water and had a significant effect on the retention of dental biofilm after 24h
O uso de dispositivos ortodônticos tem sido associado ao aumento da retenção de biofilme dentário. Neste estudo, foi testado o efeito de coberturas hidrófobas,baseadas em organo-silanos (flourados ou não), no aumento do ângulo de contato e redução de acúmulo de biofilme inicial em dispositivos ortodônticos. Dois tipos diferentes de soluções hidrófobas foram testadas: solução hidrófoba 1 (SH1), obtida pela diluição de 2,5% de hexadecil-trietóxi-silano em etanol, e solução hidrófoba 2 (SH2), composta por 2,5% de perfluorodecil-trietóxi-silano diluído em dimetilsulfóxido. As soluções foram aplicadas em substratos cerâmico e de aço inox e, via processo sol-gel e reticulação, foram formadas redes siloxanas na superfície dos dispositivos. O efeito das coberturas foi avaliado em duas etapas. Na primeira etapa, buscando a caracterização da superfície, foi analisado o ângulo de contato com água. Placas de aço inox e alumina policristalina foram preparadas, aplicando ou não jateamento prévio das superfícies com partículas de alumina. Foi observado aumento significativo do ângulo de contato com a aplicação das duas soluções hidrófobas em ambos substratos, sendo que o jateamento do substrato propiciou a formação de superfície superhidrófoba no substrato cerâmico (ângulo de contato de até 155o), enquanto superfícies hidrófobas foram obtidas no substrato aço (ângulo de contato até 123o). Na segunda fase do trabalho, avaliou-se o efeito da cobertura no acúmulo de biofilme em braquetes ortodônticos, através de modelo de microcosmos. Braquetes ortodônticos foram previamente preparados conforme os tratamentos de superfície que apresentaram melhores resultados na primeira fase (SH1 para aço, SH2 para cerâmica). Foi avaliado o efeito da cobertura na formação de biofilme em períodos de 12h e 24h (controles: substratos não-recobertos e substratos jateados). Os resultados mostraram que as coberturas hidrófobas não resultaram em efeito significativo no acúmulo de biofilme no tempo 12h, entretanto todos os tratamentos de cobertura reduziram de forma significativa o acúmulo de biofilme sobre os braquetes metálicos e cerâmicos comparados aos grupos controle no período 24h. Foi observada relação de redução exponencial significativa entre ângulo de contato e acúmulo de biofilme para o tempo 24h. Dessa forma, conclui-se que a aplicação de coberturas (super)-hidrófobas reticuladas via processo sol-gel na superfície de dispositivos ortodônticos metálicos e cerâmicos reduziu o molhamento das superfícies em contato com a água e teve efeito significativo na retenção de biofilme bucal sobre esses dispositivos após 24h
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Ermeydan, Mahmut Ali. "Wood cell wall modification with hydrophobic molecules." Phd thesis, Universität Potsdam, 2014. http://opus.kobv.de/ubp/volltexte/2014/7132/.
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Wood is used for many applications because of its excellent mechanical properties, relative abundance and as it is a renewable resource. However, its wider utilization as an engineering material is limited because it swells and shrinks upon moisture changes and is susceptible to degradation by microorganisms and/or insects. Chemical modifications of wood have been shown to improve dimensional stability, water repellence and/or durability, thus increasing potential service-life of wood materials. However current treatments are limited because it is difficult to introduce and fix such modifications deep inside the tissue and cell wall. Within the scope of this thesis, novel chemical modification methods of wood cell walls were developed to improve both dimensional stability and water repellence of wood material. These methods were partly inspired by the heartwood formation in living trees, a process, that for some species results in an insertion of hydrophobic chemical substances into the cell walls of already dead wood cells,
In the first part of this thesis a chemistry to modify wood cell walls was used, which was inspired by the natural process of heartwood formation. Commercially available hydrophobic flavonoid molecules were effectively inserted in the cell walls of spruce, a softwood species with low natural durability, after a tosylation treatment to obtain “artificial heartwood”. Flavonoid inserted cell walls show a reduced moisture absorption, resulting in better dimensional stability, water repellency and increased hardness. This approach was quite different compared to established modifications which mainly address hydroxyl groups of cell wall polymers with hydrophilic substances. In the second part of the work in-situ styrene polymerization inside the tosylated cell walls was studied. It is known that there is a weak adhesion between hydrophobic polymers and hydrophilic cell wall components. The hydrophobic styrene monomers were inserted into the tosylated wood cell walls for further polymerization to form polystyrene in the cell walls, which increased the dimensional stability of the bulk wood material and reduced water uptake of the cell walls considerably when compared to controls. In the third part of the work, grafting of another hydrophobic and also biodegradable polymer, poly(ɛ-caprolactone) in the wood cell walls by ring opening polymerization of ɛ-caprolactone was studied at mild temperatures. Results indicated that
polycaprolactone attached into the cell walls, caused permanent swelling of the cell walls up to 5%. Dimensional stability of the bulk wood material increased 40% and water absorption reduced more than 35%. A fully biodegradable and hydrophobized wood material was obtained with this method which reduces disposal problem of the modified wood materials and has improved properties to extend the material’s service-life.
Starting from a bio-inspired approach which showed great promise as an alternative to standard cell wall modifications we showed the possibility of inserting hydrophobic molecules in the cell walls and supported this fact with in-situ styrene and ɛ-caprolactone polymerization into the cell walls. It was shown in this thesis that despite the extensive knowledge and long history of using wood as a material there is still room for novel chemical modifications which could have a high impact on improving wood properties.Der nachwachsende Rohstoff Holz wird aufgrund seiner guten mechanischen Eigenschaften und der leichten Verfügbarkeit für viele Anwendungszwecke genutzt. Quellen und Schrumpfen bei Feuchtigkeitsänderungen des hygroskopischen Werkstoffs Holz limitieren jedoch die Einsatzmöglichkeiten. Ein weiteres Problem stellt der mitunter leichte Abbau – u.a. bei feuchtem Holz - durch Mikroorganismen und/oder Insekten dar. Durch chemische Modifizierungen können die Dimensionsstabilität, die Hydrophobizität und die Dauerhaftigkeit verbessert und damit die potentielle Lebensdauer des Werkstoffes erhöht werden. Dabei ist die dauerhafte Modifikation der Zellwand nur äußerst schwer realisierbar. Inspiriert von der Kernholzbildung in lebenden Bäumen, ein zellwandverändernder Prozess, der Jahre nach der Holzbildung erfolgt, wurden im Rahmen dieser Arbeit neue Ansätze zur chemischen Modifizierung der Zellwände entwickelt, um die Dimensionsstabilität und Hydrophobizität zu erhöhen. Der erste Teil der Arbeit ist stark vom Prozess der Kernholzbildung inspiriert, eine abgeleitete Chemie wurde verwendet, um die Zellwände von Fichte, einem Nadelholz von geringer natürlicher Dauerhaftigkeit, zu modifizieren. Kommerziell verfügbare hydrophobe Flavonoide wurden nach einem Tosylierungsschritt erfolgreich in die Zellwand eingebracht, um so „artifizielles Kernholz“ zu erzeugen. Die modifizierten Holzproben zeigten eine verringerte Wasseraufnahme, die zu erhöhter Dimensionsstabilität und Härte führte. Dieser Ansatz unterscheidet sich grundlegend von bereits etablierten Modifikationen, die hauptsächlich hypdrophile Substanzen an die Hydroxylgruppen der Zellwand anlagern. Der zweite Teil der Arbeit beschäftigt sich mit der Polymerisation von Styren in tosylierten Zellwänden. Es ist bekannt, dass es nur eine schwache Adhäsion zwischen den hydrophoben Polymeren und den hydrophilen Zellwandkomponenten gibt. Die hydrophoben Styren-Monomere wurden in die tosylierte Zellwand eingebracht und zu Polystyren polymerisiert. Wie bei der Modifikation mit Flavonoiden konnte eine erhöhte Dimensionsstabilität und reduzierte Wasseraufnahme der Zellwände beobachtet werden. Im dritten Teil der Arbeit wurde das biologisch abbaubare, hydrophobe poly(ɛ-caprolacton) in der Zellwand aufpolymerisiert. Die Ergebnisse deuten darauf hin, dass Polycaprolacton in der Zellwand gebunden ist und zu einer permanenten Quellung führt (bis zu 5 %). Die Dimensionsstabilität nahm um 40 % zu und die Wasseraufnahmerate konnte um mehr als 35 % reduziert werden. Mit dieser Methode kann nicht nur dimensionsstabileres Holz realisiert werden, auch biologische Abbaubarkeit und damit eine einfache Entsorgung sind gewährleistest.
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Cochin, D., P. Hendlinger, and André Laschewsky. "Polysoaps with fluorocarbon hydrophobic chains." Universität Potsdam, 1995. http://opus.kobv.de/ubp/volltexte/2008/1734/.
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A series of amphiphilic copolymers is prepared by copolymerization of choline methacrylate with 1,1,2,2-tetrahydroperfluorooctyl methacrylate in varying amounts. The copolymers bearing fluorocarbon chains are studied concerning their effects on viscosity, solubilization and surface activity in aqueous solution, exhibiting a general behavior characteristic for polysoaps. The results are compared with the ones obtained for an analogous series of amphiphilic copolymers bearing hydrocarbon chains.
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Quyum, Abdul. "Water migration through hydrophobic soils." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ65008.pdf.
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Singh, Baljit. "Studies on hydrophobic dendrimer nanoparticles." Thesis, University College London (University of London), 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428133.
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Aumaitre, Elodie. "Viscoelastic properties of hydrophobin layers." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607660.
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Matthews, Andrew Ernest. "Synthesis of hydrophobic crosslinkable resins." Thesis, Kingston University, 1989. http://eprints.kingston.ac.uk/20528/.
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After reviewing the literature relating to the synthesis and properties of hydrophobic materials, and then considering potential methods for their synthesis, a route for the preparation of novel materials was chosen. A reaction scheme involving the condensation of an excess of 1,4-bis (chloromethyl) benzene with bisphenolic compounds, and conversion of the resultant chloromethyl products to their vinyl analogues is described. A variety of methods were used to accomplish the initial etherification. The use of dimethyl acetamide and potassium carbonate was found to reduce the incidence of side reactions. The vinylation stage, using the Wittig reaction was also studied. The products were characterised by NMR and IR spectroscopy and by gel permeation and high perfonnance liquid chromatography. The curing reaction of the vinyl terminated material was studied using differential scanning calorimetry. The reaction product derived from bisphenol A was cured into various specimens, and the physical properties of the material examined. The polymer combines reasonable mechanical properties with one of the lowest water absorption maximov reported in the literature for non-fluorinated thennosets. On immersion in water at 700 C. the absorption maximov was 0.28% by weight. The thermooxidative degradation of the base material was also examined.
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Pan, Lei. "Hydrophobic Forces in Wetting Films." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/76918.
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Flotation is an important separation process used in the mining industry. The process is based on hydrophobizing a selected mineral using an appropriate surfactant, so that an air bubble can spontaneously adhere on the mineral surface. The bubble-particle adhesion is possible only when the thin film of water between the bubble and particle ruptures, just like when two colloidal particles or air bubbles adhere with each other. Under most flotation conditions, however, both the double-layer and dispersion forces are repulsive, which makes it difficult to model the rupture of the wetting films using the DLVO theory.
In the present work, we have measured the kinetics of film thinning between air bubble and flat surfaces of gold and silica. The former was hydrophobized by ex-site potassium amyl xanthate, while the latter by in-site Octadecyltrimetylammonium chlroride. The kinetics curves obtained with and without theses hydrophobizing agents were fitted to the Reynolds lubrication theory by assuming that the driving force for film thinning was the sum of capillary pressure and the disjoining pressure in a thin film. It was found that the kinetics curves obtained with hydrophilic surfaces can be fitted to the theory with the disjoining pressure calculated from the DLVO theory. With hydrophobized surfaces, however, the kinetics curves can be fitted only by assuming the presence of a non-DLVO attractive force (or hydrophobic force) in the wetting films. The results obtained in the present work shows that long-range hydrophobic forces is responsible for the faster drainage of wetting film.
It is shown that the changes in hydrophobic forces upon the thin water film between air bubble and hydrophobic surface is dependent on hydrophobizing agent concentration, immersion time and the electrolyte concentration in solution. The obtained hydrophobic forces constant in wetting film K132 is compared with the hydrophobic forces constant between two solid surfaces K131 to verify the combining rule for flotation.Master of Science
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Boyett, Robin Ernest. "Computational studies of hydrophobic porphyrins." Thesis, University of Sussex, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241621.
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Barnier, Claudie. "Biodiversité et fonctionnalité des biofilms oléolytiques en milieu marin." Thesis, Pau, 2018. http://www.theses.fr/2018PAUU3032/document.
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En milieu marin le carbone organique particulaire (POC) représente 25 % du carbone organique total. Sa dégradation est réalisée par des microorganismes hétérotrophes ayant mis en place diverses stratégies pour parvenir à le dissoudre et l’assimiler. Peu d’études se sont intéressées à la dégradation des composés polymériques et/ou hydrophobes, quasiment insolubles dans l’eau constituant le POC. Parmi ces composés, on retrouve les lipides et les hydrocarbures regroupés sous le terme de COH (composés organiques hydrophobes). La dégradation des COH est réalisée par des bactéries dîtes oléolytiques ayant entre autre pour stratégie la formation de biofilms également qualifiés d’oléolytique. Nos connaissances sur la diversité et la fonctionnalité des biofilms oléolytiques se limitent actuellement aux bactéries spécifiquement étudiées pour leur capacité à dégrader les HC. Ainsi la dégradation des lipides est souvent négligée alors que cette famille de molécules représente une part significative du POC.La diversité taxonomique des bactéries formant des biofilms oléolytiques a été déterminée par un criblage de 199 souches marines sur 4 substrats : un alcane (paraffine), un triglycéride (tristéarine), un acide gras (acide palmitique) et une cire (l’hexadécyl palmitate). Cette étude a révélé que les bactéries oléolytiques (formant un biofilm sur au moins 1 des substrats) sont relativement répandues parmi les bactéries marines puisque qu’elles représentent 18.7 % des souches testée. Cette étude montre également que les bactéries capables d’assimiler les alcanes sont également capables d’assimiler au moins un lipide. Les bactéries hydrocarbonoclastes, jusqu’alors décrites comme spécialisées, voir restreintes à l’assimilation des hydrocarbures, présentent donc une gamme de substrats s’étendant aux lipides. La corrélation positive entre la capacité d’assimilation des alcanes et l’assimilation des lipides suggère un lien physiologique entre l’assimilation de ces deux familles de COH. L’activité lipase qui est essentielle à l’assimilation des triglycérides mais pas à l’assimilation des alcanes, a été mesurée dans des cultures de souches oléolytiques poussant sur acétate, triglycéride ou hexadécane. Comme attendu, les cultures sur triglycérides montrent toutes une surexpression de l’activité lipases par rapport aux cultures sur acétate. Les cultures sur hexadécane montraient aussi une surexpression de l’activité lipase renforçant l’idée d’un lien physiologique entre dégradation des alcanes et dégradation des lipides. De plus les souches oléolytiques n’ont pas montré de capacité à former un biofilm sur une surface inerte hydrophobe telle que le polystyrène ou sur une surface hydrophile telle que le verre à la hauteur de celles constaté sur COH. Une étude quantitative de l’adhésion sur COH et substrats inertes réalisée par microscopie montre que l’adhésion (dans les conditions testées) n’est pas un facteur déterminant de la formation de biofilm sur ces mêmes substrats. Cela suggère que la spécificité de formation de biofilm sur les substrats COH, ne réside pas dans l’adhésion mais vraisemblablement dans les étapes de développement du biofilm plus tardives.Enfin, les biofilms oléolytiques mettant en jeux des produits extracellulaires (enzymes et facteurs de solubilisation) qui constituent des biens communs, sont propices à l’établissement de comportements sociaux. Nous avons mis en évidence des comportements synergiques (5/8 des comportements observés) ou compétitifs au sein de biofilm oléolytiques (3/8 des comportements observés)Particulate organic carbon (POC), in marine environment, accounts for 25% of total organic carbon. POC degradation is carried out by heterotrophic microorganisms which have developed strategies to dissolve and assimilate it. Few studies have investigated the degradation of the polymeric and / or hydrophobic components of POC, which are almost insoluble in the water. Among these compounds, there are lipids and hydrocarbons (HC) grouped under the term of HOCs (hydrophobic organic compounds). The degradation of the HOCs is carried out by oleolytic bacteria which form biofilms at the HOC– water interface. Our knowledge of the diversity and functionality of oleolytic biofilms is mostly limited to HC degrading bacteria, while the degradation of lipids is often neglected although this family of molecules represents a significant part of the POC. A screening of 199 marine strains on 4 substrates: an alkane (paraffin), a triglyceride (tristearin), a fatty acid (palmitic acid) and a wax ester (hexadecyl palmitate) was performed to determine the taxonomic diversity of bacteria able to form oleolytic biofilms. This study revealed that oleolytic bacteria (forming a biofilm on at least 1 substrate) were relatively widespread among marine bacteria since they represented 18.7% of tested strains. This study also showed that bacteria able to assimilate alkanes were also able to assimilate at least one lipid. Hydrocarbonoclastic bacteria, previously described as specialized, or restricted to the assimilation of hydrocarbons, have actually a substrate range spanning from HC to lipids. The positive correlation between the ability to form a biofilm on alkanes and on lipids suggested a physiological link between the assimilation of these two HOC families. The lipase activity, which is essential for triglycerdides assimilation but not for the alkanes assimilation, was measured in oleolytic strains cultures growing on acetate, triglyceride or hexadecane. As expected, overexpression of lipase activity was observed in cultures on triglycerides compared to cultures on acetate. Moreover, overexpression of lipase activity was also observed in cultures on hexadecane reinforcing the idea of a physiological link between alkanes and lipids degradation.Oleolytic strains exhibited a very weak ability to form a biofilm on the inert surfaces (non-nutritive) polystyrene or glass compared to the HOC nutritive surface indicating that oleolytic strains have a specificity for HOC to form a biofilm. A quantitative study of adhesion on HOC and inert substratums carried out by microscopy shows that adhesion (in the tested conditions) is not a determining factor of the biofilm formation on these same substrates. This suggests that the specificity of biofilm formation on HOC substrates does not reside in adhesion but presumably in later biofilm development stages.Lastly, oleolytic biofilms, involving extracellular products (enzymes and solubilization factors) that constitute public goods, are favorable to the establishment of social behaviors. We have demonstrated synergistic behaviors (5/8 of observed behaviors) or competitive behaviors (3/8 of observed behaviors) in oleolytic biofilms
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Boudot, Mickael. "Elaboration et caractérisation d'un vernis antireflet sol-gel innovant pour application dans les systèmes d'écrans embarqués en aéronautique." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066387/document.
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Des revêtements antiréflectifs hydrophobes à bas indice de réfraction ont été synthétisés sous forme de couches minces nanométriques de silice mésoporeuses par chimie sol gel couplée à un procédé de dépôt par dip coating sur substrats polymériques thermosensibles de polyméthacrylate de méthyle (PMMA) et de triacétate de cellulose (TAC). Les couches minces de silice pure et hybride ont été durcies par traitement en vapeur d’ammoniaque (TVA) à température ambiante. Les propriétés optiques, mécaniques et de résistance chimique des revêtements ont été optimisées et des mécanismes décrivant les modifications de la structuration induit par TVA selon la composition chimique des films ont été proposés grâce à l’étude de l’influence des conditions et des temps de traitement en vapeur d’ammoniaque. La condensation et la stabilisation de vapeur d’eau à l’intérieur de films de silice mésoporeux hydrophobes à l’aide de vapeur d’alcool ont été réalisées à température et pression ambiantes. L’étude de l’influence de la chimie de surface, de la taille des pores ainsi que des pressions partielles en eau et alcool, et de la nature du co-adsorbant alcoolique a permis de mettre en lumière les mécanismes d’adsorption et de confinement d’eau dans des nano-cavités hydrophobes. La diffusion d’eau à l’intérieur de monolithes de xérogel de silice millimétriques a été rapportée en utilisant pour la première l’ellipsométrie environnementale in situ. Des sujets aussi variés que la réalisation de films à gradient de fonctionnalité, la fabrication d’actuateurs sensibles à l’humidité à partir de films minces inorganiques, la synthèse de couches minces mésostructurées de BaTiO3 et la mise de forme 3D de films de quartz sont discutés dans ce manuscritLow refractive index hydrophobic antireflective coatings were synthetized as mesoporous nanometric thin silica films by use of sol gel chemistry coupled with the dip coating process on thermo sensitive polymeric substrates such as poly(methyl methacrylate) (PMMA) and cellulose triacetate (TAC). Thin films of pure and hybrid silica were stiffened by ammonia vapor treatment (AVT) at room temperature. Optical, mechanical and chemical stability of those coatings were optimized and the AVT-induced mechanisms of structuration depending on the chemical composition of silica films were proposed after the study of the influence of the ammonia treatment conditions and duration. Alcohol-assisted water vapor condensation and stabilization in hydrophobic mesoporous silica thin films were displayed at room temperature and atmospheric pressure. Study of the influence of surface chemistry and pore size, as well as partial vapor pressure of water and alcoholic co-adsorbant, and chemical nature of the alcohol allowed us to determine the mechanisms of water adsorption and confinement in hydrophobic nano-cavities. Water diffusion into millimetric scaled silica xerogel monoliths was reported using in situ environmental ellipsometry for the first time. Other subject as different as the production of graded functional films, fabrication of inorganic thin films based humidity sensitive actuators, synthesis of BaTiO3 mesostructured thin films and shaping of 3D quartz films are also discussed
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Yang, Fan 1980. "Solvent mediated interaction between hydrophobic spheres." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84087.
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We develop a coarse grained methodology to study solvent mediated interactions between two or more hydrophobic spheres. The free energy of a configuration of two hydrophobic hard spheres is calculated as a function of their separation to understand the thermodynamic force between them mediated by water. The range of the hydrophobic interaction is found to be of the order of the equilibrium correlation length of water; beyond this range the hydrophobicity induced force is negligible. We also examine the free energy landscape corresponding to the two interacting hydrophobic spheres, and find a new intermediate state between the two states of separate and non-interacting spheres and a weakly bound cluster. The nature of this intermediate state changes depending on the size of the spherical particles, and even disappears beyond a minimum critical radius. Our results are relevant to the understanding of hydrophobic mediated interactions in coarse grained models of protein folding and protein protein interactions which, to date, have only accounted for hydrophobicity in an empirical way.
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Lipnizki, Frank. "Hydrophobic pervaporation : process integration and optimisation." Thesis, University of Bath, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343775.
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Baines, Fiona Louise. "Water-soluble hydrophilic-hydrophobic block copolymers." Thesis, University of Sussex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283139.
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Gupta, Vipul. "Deposition and Characterization of Hydrophobic Coatings." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3859.
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Hydrophobic coatings find application in various sectors of the economy including to electronics, textiles, optical devices, and in scientific and commercial equipment. These different applications demand that different hydrophobic coatings posses a range of properties that may include smoothness or roughness, thicknesses on the order of a monolayer or a micron, robustness or the ability to dissolve quickly, transparency or opacity, water resistance or water permeability, electrical conductivity, oleophobicity, etc. However, whatever the final/desired properties, deposition via dry-deposition processes offers significant advantages, including greater reproducibility, increased environmental friendliness, and cost effectiveness on an industrial scale. Herein I explore the chemical vapor deposition of silanes and the characterization of a commercial, hydrophobic coating to better prepare and understand hydrophobic coatings on different materials. One of the characterization techniques I used frequently in these studies is X-ray photoelectron spectroscopy (XPS). Accordingly, in Chapter 2 of this thesis I discuss this technique vis-à-vis the chemical shifts it detects, which reflect the oxidation states of materials being probed. In particular, I discuss a recommendation made over a decade ago by Gion Calzaferri for 'fixing' the problem of oxidation numbers as applied to organic materials and show how XPS confirms his suggestion. In Chapter 3 I introduce hydrogen as an etch/cleaning gas for silicon wafers. I first show that, like argon and oxygen plasmas, hydrogen plasmas will effectively clean silicon wafers. However, I then show that hydrogen plasma treatment leads to a silicon surface that is chemically different than those prepared with the other plasmas and that undergoes silanization to a greater extent -- the resulting surfaces have higher water contact angles and thicknesses. In Chapter 4 I study the deposition of a potential barrier layer for water, which was prepared from an aza silane: N-n-butyl-aza-2,2-dimethoxysilacyclopentane (1) in a molecular layer deposition (MLD)-like process using either water or ammonium hydroxide as the second half reactant. This molecule has the interesting property of undergoing self-limiting growth, where the termination of this growth is accelerated by use of an ammonium hydroxide catalyst. Interestingly, films of 1 are considerably thicker on nylon than on silicon, which is explained by nylon acting as a water reservoir in the reaction. In Chapter 5 I show the careful characterization of the hydrophobic coating on an Apple iPod nano, which was probed by ToF-SIMS, wetting, and XPS. I could identify that the coating is only applied to the touchscreen of the device. SIMS suggested that the fluorinated coating contains oxygen, which should add to its biodegradability. Finally, in Chapter 6 I make recommendation for future work in these areas.
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Ghasemi, Mohsen. "Evaporation of Water in Hydrophobic Confinement." Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1503094472074141.
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Baba, N. M. "Hydrophobic polymers and nanocomposites from cassava." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1435602/.
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This project aims to benefit the sub-Saharan African economies by exploiting cassava for chemical feedstock for materials production. It anticipates the industrial changes that will follow from increased petroleum price and regulatory control of embedded fossil carbon. It offers a way to integrate industrial and agricultural sectors. Initially, glucose and fructose were dehydrated by reactive distillation over a sulfated zirconia catalyst and 1-butyl-3-methylimidazolium chloride (BMIM Cl) ionic liquid as solvent under a nitrogen atmosphere at 180 oC to produce 5-(hydroxymethyl) furan (5-HMF) as a precursor for polymeric materials. Solvent, catalyst and reaction conditions were varied to improve the yield of 5-HMF. Yields of 82% and 65% were obtained using fructose and glucose substrates with this catalyst. Secondly, 2,5-furandicarboxylic acid (FDCA) and 2,5-bis-(hydroxymethyl)furan (BHMF) were synthesised as monomers from 5-HMF. The aldehyde group of 5-HMF was oxidized using potassium permanganate to FDCA with 80% yield achieved. BHMF was synthesised from 5-HMF using sodium borohydride with 88% yield achieved. The third part focuses on the polymerization of FDCA with the following diols: 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol and BHMF via esterification reactions at 160-200 oC using titanium (IV) n-butoxide catalyst. All diols produced polymers under the same conditions. The difference within this family of polymers was the number of carbon atoms in the linking diols and that BHMF had a different diol structure with a furan ring attached. Furthermore, a study of the interaction of all the monomers and the 5-HMF with Na-montmorillonite clay was made. It was observed that all were intercalated into the clay paving the way for the manufacture of nanocomposites. Finally, all the polymers were shown to be hydrophobic with PBH-2,5-F more hydrophobic with a contact angle of 91o compared to others. Water absorption, dielectric constant and mechanical properties of the polymers were recorded.
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Wang, Jihang. "Modeling Hydrophobic Effects at different lengthscales." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/161.
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Understanding hydrophobic effects at different length scales is relevant to many complex and poorly understood everyday phenomena in materials science and biology. In this thesis, a variety of theory/computational methods in statistical physics and statistical mechanics are used to address three separated, but interconnected problems: (1) How solvation free energy scales with a partical size that is charged? This problem has never been attempted to solve before despite its immense importance in colloidal and protein solutions (J. Wang, D. Bratko, K. Leung and A. Luzar, Hydrophobic hydration at different length-scales: manipulating the crossover by charges, to be submitted to J. Stat. Phys. (Special issue on Water and Associated Liquids)); (2) Can onset to capillary evaporation, seen in some protein complexes with large hydrophobic areas be predicted in a simple way? A simple coarse-grained model of water/protein system, which is developed here shows the conditions for wet and dry hydrophobic protein cavities, and is able to reproduce all atom simulation results. The method should serve as an intermediate step between the initial screening of protein hydrophobic cavities and expensive molecular simulations (J. Wang, S. Kudesia, and A. Luzar, Computational probe of dewetting events in protein systems, in preparation for submission to J. Phys. Chem. B); (3) How to predicts hydrophobicity of a mixed surface from the knowledge of its pure constituents? To this end, wetting free energy on synthetic and biological heterogeneous surfaces is studied. Two distinct mechanisms responsible for their non-additivity have been identified in each case (J. Wang, D. Bratko and A. Luzar, Probing surface tension additivity on heterogenous surfaces: a molecular approach, Proc. Natl. Acad. Sci, under revision)
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Bonfante, Gwenaël. "Electromouillage et fiabilité : investigation de matériaux diélectriques et de couches minces hydrophobes." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1289.
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Dans le but d'améliorer la fiabilité des technologies utilisant l'électromouillage, l'objectif de cette thèse est d'étudier les mécanismes de vieillissement de matériaux diélectriques et hydrophobes utilisés en électromouillage et d'appliquer ensuite le protocole de caractérisation établi, à de nouveaux matériaux. Cette thèse s'articule en trois parties. Dans une première partie, afin de caractériser finement les propriétés d'hydrophobie de surfaces et de déterminer plus particulièrement leur polarité, nous avons mis au point une méthode de mesure de la polarité de surface basée sur le mouillage de deux liquides sur une surface, ce qui apporte une précision accrue avec un minimum de mesures. Dans une deuxième partie, nous avons étudié différents revêtements utilisés en électromouillage avant et après vieillissement. Nous nous sommes plus particulièrement intéressés aux films hydrophobes largement utilisés dans les systèmes optiques et de micro-laboratoires comme le Fluoropel©, le Cytop© et le parylène C. Cette étude montre une altération non négligeable des performances des matériaux de manière reproductible. L'hystérésis de mouillage, l'angle de contact au repos ainsi que les propriétés de cohésion des couches ont été étudiés afin de mettre en évidence les paramètres critiques à la durée de vie.Dans la dernière partie, nous avons cherché à mettre au point une méthode de dépôt d'un nouveau matériau hydrophobe par deux techniques de synthèse ; la voie sol-gel et la pulvérisation cathodique (PVD). Ainsi, un sol de précurseur à base du métal applicable pour la préparation de couches minces de son oxyde a été élaboré. La solution est obtenue à partir d'un précurseur synthétisé au laboratoire et stabilisée par des chélatants (acétylacétone). La stabilité de la solution ainsi que la procédure de dépôt sont présentées et les revêtements recuits déposés par sol-gel et PVD sont caractérisés par DRX et d'un point de vue morphologique (MEB, microscope optique…). Si, il fut possible de préparer par la méthode sol-gel des films de 300nm couvrants, leur forte rugosité n'a pas permis de les tester en électromouillage. Par la méthode PVD, nous avons pu réaliser des couches de 400 nm d'épaisseur, très lisses et utilisables en électromouillage. Ces films donnent de très bons résultats en électromouillage sur substrats plans et en lentilles liquidesIn order to increase the technologies reliability using electrowetting, this work aims to study the mechanisms of ageing on dielectric and hydrophobic materials used in electrowetting as well and to apply this study to new materials. This thesis is composed of three parts.First, to be able to characterize precisely the hydrophobic properties of these surfaces and especially their surface polarity, we established a method to measure the surface polarity based on wettability of two liquids on a surface permitting a better precision with less measurements. In a second part, we studied different films used in electrowetting before and after ageing around 90°C for one week in order to simulate a long term ageing at an ambient temperature. Widely used hydrophobic coating used in optical systems and lab-on-chip will be mainly characterized such as Fluoropel©, Cytop© and parylène C. This work shows the visible alteration of material performances in a reproducible way. Wetting hysteresis and natural contact angle with the cohesive properties of the coatings are studied in order to establish critical parameters for the life time.Finally, we tried to establish a method to deposit a hydrophobic metal oxide coating by two ways, sol-gel technic with dip-coating deposition and by PVD. A precursor sol made of the metal usable to deposit its oxide thin films has been elaborated. The solution is prepared from the synthesized precursor and stabilized by chelatant (acetylacetone). The solution stability as well as the deposition method used are presented and the annealed coatings deposited by sol-gel and PVD are characterized by XRD and morphologically (SEM, optic microscope …). By the sol-gel method, covering coatings of about 300nm have been made. However, because of the roughness, no electrowetting experiments could have been achieved. By PVD, we have deposited coatings of 400nm thickness, very smooth and usable in electrowetting. These coatings give very good results in electrowetting on plane substrates and liquid lenses
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Stolz, Aude. "Systèmes fonctionnels à base de carbone et interactions avec l’eau : du nano-confinement aux éponges (super)hydrophobes." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1296/document.
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Les matériaux carbonés présentent de nombreux avantages pour les domaines des nanotechnologies et de l'environnement.La mixité de chiralité des nanotubes de carbone limite leur application dans les appareils électroniques et le nano-confinement. Dans une première partie, ce travail de thèse s'est concentré sur la séparation en chiralité de nanotubes de carbone de type CoMoCAT, afin d'élaborer de nouveaux nano-conteneurs.Après sélection en chiralité, nous avons évalué les propriétés sous hautes pressions des fagots de nanotubes sélectionnés, et leur interaction avec l'eau. Les résultats ont montré que les fagots supportent des pressions jusqu'à 17 GPa, avant de subir un effondrement radial réversible, permettant de les utiliser en tant que nano-enclumes.L'élaboration d'une éponge de carbone (super)hydrophobe pour le traitement des eaux après pollution aux hydrocarbures a été décrite dans une seconde partie. La pyrolyse de mousses polymères a permis de conserver la très grande porosité de la mousse (> 99%), tout en lui conférant des propriétés proches de la superhydrophobie et de grandes capacités d'absorption de pétrole et solvants organiques (85-200 g/g). L'élasticité du matériau permet sa régénération par simple compression mécanique : récupération du polluant et réutilisation de l'absorbant. De plus, cette caractéristique reste valable même après une centaine de cycles de compression-décompression, en conservant 81% de sa capacité d'absorption dans le cas du pétrole brutCarbon materials present many advantages for the nanotechnology and environment fields. The chirality mixity of carbon nanotubes limits their application in electronic devices and the nano-confinement. In the first part, this thesis has focused on the chirality separation of CoMoCAT carbon nanotubes, in order to elaborate new nano-containers.After the chirality selection, the properties of selected nanotubes bundles under high pressure were evaluated, as well as their interaction with water. The results show that the bundles support pressures until 17 GPa, before to undergo a reversible collapse, allowing their application as nano-anvils.The (super)hydrophobic carbon sponge elaboration for the clean-up of water polluted by oils was described in the second part. The polymeric foams pyrolysis allows to keep the very high foam porosity (> 99%), to give properties next to the superhydrophobicity and large absorption capacities in oils and organic solvents (85-200 g/g). The material elasticity allows its regeneration by simple mechanical compression : recovery of pollutant and re-use of the absorbant. Moreover, this feature remains valid after a hundred compression-decompression cycles, with 81% of the initial crude oil absorption capacity
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Macdonald, Ryan. "The Effects of Trimethylamine-N-Oxide and Guanidinium Chloride on Aqueous Hydrophobic Contact-Pair Interactions." Elsevier - Biophysical Chemistry, 2013. http://hdl.handle.net/1993/30162.
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Trimethylamine-N-oxide (TMAO) and guanidinium chloride (GdmCl) are both highly studied molecules in the field of protein folding/unfolding. Thermodynamic studies have shown that TMAO, an organic osmolyte, is a strong stabilizer of the protein folded state, while GdmCl is known to be one of the most effective protein denaturants. Although TMAO and GdmCl are well studied the mechanism by which they stabilize and denature proteins, respectively, is not well understood. In fact there are few studies looking at their effects on hydrophobic interactions. In this work we determine the effect of TMAO and GdmCl on hydrophobic interactions, by looking at the model system of phenyl and alkyl hydrophobic contact pairs. Contact pair formation is monitored through the use of fluorescence spectroscopy, i.e., measuring the intrinsic phenol fluorescence being quenched by carboxylate ions. Hydrophobic interactions are isolated from other interactions through a developed methodology. The results show that TMAO addition to the aqueous solvent destabilizes hydrophobic contact-pairs formed between phenol and carboxylate ions. The TMAO acts as a “denaturant” for hydrophobic interactions. For GdmCl the data shows that for small alkyl groups, acetate and propionate, hydrophobic contact-pairs are slightly stabilized or are not affected, respectively. For the larger alkyl groups GdmCl disrupts contact pair formation and destabilizes them. GdmCl’s effect on hydrophobic interactions shows a size dependence on carboxylate ion size, i.e., as carboxylate ion tail length increases the contact pair formed with phenol is destabilized to a greater degree.
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Rodrigues, Sabrina Páscoli. "Galtier, Pasteur e Roux: estudos sobre a raiva (1879 1885)." Pontifícia Universidade Católica de São Paulo, 2010. https://tede2.pucsp.br/handle/handle/13453.
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Nowadays, in general, the chemist Louis Pasteur (1822-1895) takes all the credit for the researches that led to the production of the vaccine against hydrophobia. This dissertation deals with Pasteur s contributions concerning this subject, from 1879 to1885, taking into account its context. It also discusses the contributions from the veterinary Pierre Victor Galtier (1846-1908) and the physician Émile Roux (1853-1933). The aim of this research is trying to elucidate the existence of a possible superiority or priority concerning some important contributions related to rabies considering Pasteur, Galtier and Roux s publications on the subject during the period. This dissertation contains an introduction and four chapters. Chapter 1 provides an overview of Pasteur s researches before carrying out his researches on rabies, as well as its scientific context. Chapter 2 discusses the researches on rabies did by Galtier (1846-1908). Chapter 3 analyses the researches on rabies conducted by Pasteur and his collaborator, Roux. Chapter 4 presents some final remarks on the subject. This study led to the conclusion that the vaccine against rabies is the product of several scientists work such as Galtier, Roux and Pasteur. Besides that, it pointed out that Pasteur s contribution on the subject was not so significant as it is normally thought. Galtier and Roux should have achieved recognition indeed. Moreover, the popular version of this episode cannot be explained only taking into account Pasteur s scientific contributions on the subject
Hoje em dia, geralmente, é o químico Louis Pasteur (1822-1895) quem recebe o crédito pelas pesquisas que levaram à produção da vacina anti-rábica. Esta dissertação trata das contribuições de Pasteur sobre o assunto durante o período compreendido entre 1879 e 1895, levando em conta seu contexto. Discute também as contribuições do veterinário Pierre Victor Galtier (1846-1908) e do médico Émile Roux (1853-1933). O objetivo desta pesquisa é procurar elucidar a existência de uma possível superioridade ou prioridade em relação a importantes contribuições relacionadas à raiva considerando as publicações de Pasteur, Galtier e Roux sobre o assunto no período. Esta dissertação contém uma introdução e quatro capítulos. O Capítulo 1 oferece uma visão geral das pesquisas de Pasteur que antecederam seus estudos sobre a raiva, bem como seu contexto científico. O Capítulo 2 discute as pesquisas sobre a raiva feitas por Galtier (1846-1908). O Capítulo 3 analisa as pesquisas sobre a raiva desenvolvidas por Pasteur e seu colaborador, Roux (1853-1933). O Capítulo 4 apresenta algumas considerações finais sobre o assunto. Este estudo levou à conclusão de que a vacina contra a raiva é o produto do trabalho de vários cientistas tais como Galtier, Roux e Pasteur. Além disso, indica que a contribuição de Pasteur sobre o assunto não é tão significativa como se pensa geralmente. Certamente Galtier e Roux mereciam ter recebido um maior reconhecimento por suas contribuições. Além disso, a versão aceita popularmente sobre este episódio não pode ser explicada somente através das contribuições científicas de Pasteur
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Al-Salihi, Arfan. "Contribution à l'étude du cinquième composant du complément (C5)." Rouen, 1989. http://www.theses.fr/1989ROUES024.
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Une méthode de purification du C5, en quatre étapes, permet d'obtenir C5, C3 et H. La présence des sites hydrophobes dans C5 est mise en évidence. La localisation de ces sites est réalisée par digestion par la trypsine et analysé par électrophorèse bidimensionnelle. Par chromatographie hydrophobe, trois fragments sont isolés et caracterisés. La comparaison des compositions de ces fragments et des degrés d'hydrophobicité permet de localiser les sites hydrophobes dans le fragment alpha-2 de la chaîne peptidique alpha
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Houzelle, Marie-Christine. "Dérivés amphiphiles associatifs de la pectine diverses voies de synthèse : étude comparative des propriétés physicochimiques des solutions aqueuses en régimes dilué et semi-dilué." Vandoeuvre-les-Nancy, INPL, 1998. http://www.theses.fr/1998INPL111N.
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La pectine est un polysaccharide anionique extrait des végétaux supérieurs et, en particulier, de l'écorce des fruits et des légumes. Ce polymère a été modifié chimiquement par fixation de chaines alkyles en C₁₂, C₁₆ et C₁₈, par trois voies de synthèse différentes, de manière à obtenir des dérivés associatifs dans lesquels les chaines apolaires sont associées au squelette polymère par des liaisons covalentes et/ou des liaisons ioniques. Les propriétés physico-chimiques des différents dérivés hydrophobisés résultants ont été étudiées de façon comparative par viscosimétrie, spectrométrie de fluorescence, en rhéologie et par des mesures de tension de surface, dans l'eau pure ou en présence de sels. Quel que soit le mode de synthèse et donc de fixation des chaines hydrophobes au polymère, tous ces dérivés présentent des propriétés associatives. En régime dilué, des interactions intramoléculaires se mettent en place, conduisant à une diminution de la viscosité macroscopique du milieu. En régime plus concentré, des interactions hydrophobes intermoléculaires s'établissent, conduisant à l'obtention de solutions aqueuses de très haute viscosité, voire même de réseaux tridimensionnels physiquement pseudo - réticulés ayant l'apparence d'hydrogels. Cependant, à coté de ces ressemblances, les chaines hydrophobes ne s'organisent pas au niveau moléculaire de la même façon, selon qu'elles sont associées au squelette polysaccharidique de façon covalente ou ionique. Cette différence de structure se traduit au plan macroscopique, en particulier par des propriétés de surface et des comportements rhéologiques sensiblement dissemblables.
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Etmimi, Hussein Mohamed. "Hydrophobic core/shell particles via miniemulsion polymerization." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019/539.
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Kroeger, Thomas William 1952. "Hydrophobic partitioning of the bacteriophage MS-2." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/276963.
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In batch experiments at pH's 5 and 7, the partitioning of MS-2 between water and silica (unbonded) was compared with the partitioning between water and silica with 6.5 percent of the surface covered by hydrophobic C18 chains (bonded). The roles of double-layer and van der Waals forces in partitioning were explored by modeling the potential energies of interaction. MS-2 adsorption to unbonded silica was negligible at pH 7, but did occur at pH 5. Adsorption was independent of pH with the bonded silica and approximately 2.6 orders of magnitude greater than the unbonded at pH 5, suggesting the importance of hydrophobic partitioning. The total potential energies of interaction, which closely approach the pH-independent van der Waals potentials, are similar in magnitude for all pH's or silica types, and have no positive (repulsive) values. The insignificant contribution of the double-layer potentials suggests that these pH-dependent forces may not account for the pH-dependent adsorption observed with the unbonded silica.
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Chen, C. H. "Phase ordering of monoglyceride in hydrophobic solutions." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597547.
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In Chapter 1 the fundamentals of MG and MG-water are reviewed before embarking on studying the mixtures of MG and oils. The typical phase ordering and crystallisation process are reviewed. Understanding the physical properties of lipids is fundamentally important, hence, relevant theories regarding the phase behaviour are discussed in the following section. Chapter 2 introduces synthesis, characterisation and experimental techniques used throughout the thesis. Particular attention is given to assess the limitations of these techniques when probing the phase ordering of MG-oil. In Chapter 3 the phase diagram and the microstructure of MG in oils are presented by a set of experimental data from different techniques. Chapter 4 presents the experimental findings of the water effects in MG-oil systems. Chapter 5 considers the aging and metastability of MG-oil and its hydrated system (MG-oil with 3 wt\% water). The aging phenomena are quantified by the increase of melting enthalpy in differential scanning calorimetry (DSC) heating scans and the mechanism is understood by applying infrared spectroscopy. The changes of hydrogen bonding patterns by adding small quantity of water slows the aging process significantly. In Chapter 6 the effect of colloidal dispersions is discussed to modify the MG gel. Lipids such as MG form the gel-like material which can be widely applied in the food industry, cosmetics and other personal products. It is hoped that this thesis will provide stimulating insight into the lipid composite field and furthermore, motivate research in industry toward improvement of existing materials and discovery of innovative new products.
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Crick, C. R. "The chemistry and CVD of hydrophobic surfaces." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1332890/.
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This thesis details the use of chemical vapour deposition (CVD) to deposit hydrophobic surfaces, in addition to this, the functional properties are investigated and further characterisation of the surfaces extreme water repulsion (superhydrophobicity) is made. The design and manufacture of surfaces that repel water (hydrophobic) draws much inspiration from the natural world, including examples of superhydrophobic leaves. The way water can interact with a surface is characterised, with many examples of superhydrophobic surface generation provided from the literature, along with general routes toward their formation. The main aspects of CVD depositions are addressed and examples of hydrophobic surfaces using this technique are cited. The novel deposition of thermosetting and thermosoftening polymers has been investigated, with the role of the CVD deposition mechanism emphasised. The deposition of the polymer occurs via the preformation of polymer particles, which is not typical in CVD, these were then deposited onto the substrate. The result was an easy-to-produce and robust superhydrophobic thin film, constructed from an inherently hydrophobic material. The same principle is then expanded to silica microparticles, films of the particles were deposited on to a substrate with hydrophilic surfaces originally deposited. The silica films were subsequently rendered exceptionally superhydrophobic by a simple post-treatment. The formation of copper films is then reported, using copper nitrate precursors a relatively flat metallic copper film was formed. The films were then roughened by reaction to form copper hydroxide nano-crystals, this hydrophilic surface is again functionalised to render it superhydrophobic. All films deposited were characterised using energy dispersive X-ray analysis, glancing angle X-ray diffraction, UV/Vis spectroscopy, infra-red/Raman spectroscopy and scanning electron and atomic force microscopy were used to study surface morphology, with the hydrophobicities of each surface quantified. The superhydrophobic elastomer films underwent microbiological testing in order to examine the adhesion of bacteria. A substantial reduction in the ability of bacteria to attach to the superhydrophobic surfaces was observed and rationalised through a reduction in available contact between the media of the bacteria (water) and the surface material. The dynamic interaction between water and surfaces was examined through water bouncing. The dependence of water bouncing on surface hydrophobicity and microstructure was studied, in addition to the effect of water droplet volume and impact velocity. A new definition and scale for superhydrophobicity is proposed, through the ability of water droplets to bounce on a surface. Finally the insight gained from previous work carried out is used in developing a device for separating mixtures of oil and water, through the use of superhydrophobic meshes.
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Moradi, Sona. "Super-hydrophobic nanopatterned interfaces : optimization and manufacturing." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46588.
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This work studies in detail the effect of femtosecond laser irradiation process parameters (fluence, scanning speed and scanning overlap) on the wettability of the resulted micro/nano-patterned morphologies on stainless steel. Depending on the laser parameters, four distinctly different nano-patterns were produced, namely nano-rippled, parabolic-pillared, elongated sinusoidal-pillared and triple roughness nanostructures. All of the produced structures were classified according to a newly defined parameter, the Laser Intensity Factor (LIF) that is a function of scanning speed and fluence of laser. By increasing LIF, the ablation rate and the periodicity of the asperities increase. In order to decrease the surface energy, all of the surfaces were coated with a fluorinated alkylsilane agent. Analysis of the wettability in terms of contact angle (CA) and contact angle hysteresis (CAH) revealed enhanced superhydrophobicity for most of these structures, particularly that possessing triple roughness pattern. This also exhibited a low CAH. The high permanent superhydrophobicity of this pattern is due to the special micro-nano structure of the surface that facilitates the Cassie-Baxter state.
A new two-dimensional (2D) thermodynamic model is developed to predict the contact angle (CA) and contact angle hysteresis (CAH) of all types of surface geometries, particularly those with asperities having non-flattened tops. The model is evaluated by micro/nano sinusoidal and parabolic patterns fabricated by laser ablation. These microstructures are analyzed thermodynamically through the use of the Gibbs free energy to obtain the equilibrium CA and CAH. The effects of the geometrical details on maximizing the superhydrophobicity of the nano-patterned surface are also discussed in an attempt to design surfaces with desired and/or optimum wetting characteristics. The analysis of the various surfaces reveals the important geometrical parameters, which may lead to lotus effect (high CA>150° and low CAH<10°) or petal effect (high CA>150° and high CAH>>10°).
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Charalambous, Antonia. "Lipid oil nanodroplets for hydrophobic drug delivery." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/21956/.
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Delivery of anti-cancer drugs to tumours is a fundamental requirement for cancer treatment. However, failure of drugs to reach tumours at sufficient concentrations due to poor bioavailability, rapid metabolism and elimination compromises effective treatment. A substantial number of potent anti-cancer drugs, exhibit hydrophobic properties that hinder their clinical use. Therefore, there is an urgent need for the development of a hydrophobic drug delivery system (DDS) that aims to effectively deliver and controllably trigger the release of these agents. This may improve drug bioavailability, efficacy and reduce severe side effects. Lipid-Oil-NanoDroplets (LONDs) are nanosized nanoemulsions and are proposed as a novel hydrophobic DDS for colorectal cancer (CRC) treatment. LONDs were produced using a two-step high pressure homogenisation process, producing LONDs with size ranges between 100-300 nm. The hydrophobic vascular disrupting agent Combretastatin A4 (CA4) was encapsulated and used as a proof-of-concept for LOND evaluation in vitro and in vivo. CA4 was dispersed in triacetin or tripropionin oil to form the LOND core, stabilised by a phospholipid-shell. Using a microfluidic production platform, CA4 LONDs were attached on-chip to gas-filled, phospholipid-shelled therapeutic microbubbles (thMBs). CA4 thMBs were targeted to vascular endothelial growth factor receptor 2 (VEGFR-2) and used as LOND delivery vehicles. An external ultrasound (US) destruction pulse applied at the tumour site was used to trigger targeted release and enhance delivery. This project showed CA4 release and/or uptake from LONDs in both endothelial and human CRC cells by immunofluorescence and flow cytometry. Intratumoural delivery of CA4 LONDs was observed and quantified in CRC xenografts using liquid chromatography tandem mass spectrometry (LS-MS/MS). Administration of CA4 LONDs resulted in a modest tumour growth inhibition in vivo, while a reduction in tumour perfusion was observed with CA4 thMBs. Combination therapy of CA4 thMBs with a chemotherapeutic agent, irinotecan, further reduced tumour growth compared to irinotecan alone, potentially through reduction in tumour perfusion. These results suggest that LONDs may serve as a novel hydrophobic DDS, while thMBs could further enhance tumour specific delivery.
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Gan, Haiying. "Self-Assemblies Driven by the Hydrophobic Effect." ScholarWorks@UNO, 2011. http://scholarworks.uno.edu/td/1389.
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Water is a simple molecule but is an essential part of life. One key aspect of the properties of water is the hydrophobic effect, and whilst there is an appreciation of this phenomenon at the macro-scale (raindrops falling off leaves) and the micro-scale (the structure of cellular systems), a complete understanding at the molecular level still eludes science. Addressing this issue, our studies involve synthetic supramolecular compounds that assemble in water via the hydrophobic effect.
First of all, a novel water-soluble deep-cavity cavitand was synthesized. It possesses four endo methyl groups on top rim of the cavitand, eight water-solubilizing carboxylic acid groups coated on the cavitand exterior, and a relatively large hydrophobic interior. Compared to a previous well-studied water-soluble deep-cavity cavitand octa-acid (OA), this novel cavitand (TEMOA) possesses a non-monotonic assembly profile in the presence of a homologous series of straight-chain alkanes. Three supramolecular species were observed: 1:1, 2:2, and 2:2 and they are approximately isoenergetic. Second, we examined the guest-controlled self-sorting in assemblies. A mixture of OA and TEMOA formed hetero-capsular complex driven by the hydrophobic effect. The extent of homo- or hetero-dimerization is intimately tied to the size of the guest being encapsulated. TEMOA is less predisposed to dimerize than OA, thus TEMOA possesses the ability to form various self-assembled states, such as tetrameric and hexameric assemblies. Furthermore, we also discussed our observation of how external stimuli such as changing the nature or concentration of a co-solute salt influences a unique, unusual transition from one assembled state to another.
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Cardin, Karl Jeffrey Theodore. "Jet Rebound from Hydrophobic Substrates in Microgravity." PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/4830.
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We experimentally investigate the phenomena of large jet rebound, a mode of fluid transfer following oblique jet impacts on hydrophobic substrates. We initially seek to describe the jet rebound regimes in tests conducted in the weightless environment of a drop tower. A parametric study reveals the dependence of the flow structure on the relevant dimensionless groups such as Reynolds number and Weber number defined on the velocity component perpendicular to the substrate. We show that significantly larger diameter jets behave similarly as much smaller jets demonstrated during previous terrestrial investigations is some parameter ranges while the flow is fundamentally different in others. Level-set numerical predictions are provided for comparisons where practicable. Simple models are developed predicting landing geometry and the onset of instability that are found to yield good agreement with experiments and simulations. Improving our understanding of such jet rebound opens avenues for unique transport capabilities.
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Ronchi, Laura. "Synthesis of Hydrophobic Zeolites for Energetic Applications." Thesis, Mulhouse, 2017. http://www.theses.fr/2017MULH0678/document.
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Les zéolithes sont des solides microporeux cristallins largement utilisés en adsorption, catalyse, échange ionique et comme tamis moléculaires. Les zéolithes hydrophobes purement siliciques (zéosils) peuvent être utilisées pour le stockage et l’absorption de l’énergie mécanique par intrusion d’eau à haute pression. En fonction du système “zéosil-eau”, lorsque la pression est relâchée (extrusion), le système peut restituer, dissiper ou absorber l’énergie mécanique fournie pendant la compression (intrusion) et donc, il peut montrer un comportement de type ressort, amortisseur ou pare-chocs. Récemment, il a été remarqué que l’intrusion de solutions salines peut améliorer considérablement les performances énergétiques de ces systèmes par une augmentation de la pression d’intrusion. Pendant ce travail, l’intrusion d’eau et de solutions de LiCl a été étudiée pour différentes zéosils pour mieux comprendre la relation qui existe entre la structure des zéosils (dimension des pores, type et dimensionnalité du système poreux) et le comportement ou les performances énergétiques du système “zéosil-liquide intrusé”.Les expériences avec des zéosils qui présentent une structure à cage ont confirmé une pression d’intrusion plus faible par rapport à celles observées par les zéosils ayant une structure à canaux. La pression d’intrusion augmente fortement avec la concentration de LiCl pour les zéosils caractérisés par de petites ouvertures des pores, spécialement pour ceux qui ont des cages, tandis que cette augmentation est plus faible lorsque de grandes ouvertures de pores sont présentes. Il a été aussi montré une influence de la concentration du sel sur le comportement, probablement, due à la nature particulière des solutions très concentréesZeolites are microporous crystalline solids widely used in adsorption, catalysis, ion exchange and molecular sieving. Hydrophobic pure-silica zeolites (zeosils) can be used for mechanical energy absorption and storage by high pressure intrusion-extrusion of water. Depending on the “zeosil-water” system, when the pressure is released (extrusion), the system is able to restore, dissipate or absorb the supplied mechanical energy during the compression step (intrusion) and therefore to display a spring, shock absorber or bumper behavior. Recently, it was found that the use of aqueous salt solutions could considerably improve the energetic performances of such systems by an increase of the intrusion pressure.In this work the intrusion of water and LiCl solutions was studied for different zeosils in order to understand the relationship between the structure of zeosils (pore size, pore system type and dimensionality) and the behavior or the energetic performances of “zeosil-liquid” systems. The experiments with cage-type zeosils confirmed a lower intrusion pressure in comparison with channel-type ones. The intrusion pressure strongly increases with the LiCl content for the zeosils with small pore openings, particularly, for the cage-type ones, while for larger pores this increase is less important. An influence of salt concentration on the behavior of “zeosils-liquid” systems probably due to the particular nature of highly concentrated solutions was also shown
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Jones, Alan Wayne III. "Advancement of the Hydrophobic-Hydrophilic Separation Process." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/89067.
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Froth flotation has long been regarded as the best available technology for ultrafine particles separation. However, froth flotation has extreme deficiencies for recovering ultrafine particles that are less than 30-50 μm in size for coal and 10-20 μm for minerals. Furthermore, dewatering of flotation products is difficult and costly using currently available technologies. Due to these problems, coal and mineral fines are either lost to tailings streams inadvertently or discarded purposely prior to flotation. In light of this, researchers at Virginia Tech have developed a process called hydrophobic-hydrophilic separation (HHS), which is based originally on a concept known as dewatering by displacement (DbD). The process uses non-polar solvents (usually short-chain alkanes) to selectively displace water from particle surfaces and to agglomerate fine coal particles. The resulting agglomerates are subsequently broken (or destabilized) mechanically in the next stage of the process, whereby hydrophobic particles are dispersed in the oil phase and water droplets entrapped within the agglomerates coalesce and exit by gravity along with the hydrophilic particles dispersed in them. In the present work, further laboratory-scale tests have been conducted on various coal samples with the objective of commercial deployment of the HHS process. Test work has also been conducted to explore the possibility of using this process for the recovery of ultrafine minerals such as copper and rare earth minerals. Ultrafine streams produced less than 10% ash and moisture consistently, while coarse coal feed had no observable degradation to the HHS process. Middling coal samples were upgraded to high-value coal products when micronized by grinding. All coal samples performed better with the HHS process than with flotation in terms of separation efficiency. High-grade rare earth mineral concentrates were produced with the HHS process ranging from 600-2100 ppm of total rare earth elements, depending on the method and reagent. Additionally, the HHS process produced copper concentrates assaying greater than 30% Cu for both artificial and real feed samples, as well as, between 10-20% Cu for waste samples, which all performed better than flotation.Master of Science
Froth flotation has long been regarded as the best available technology for separating fine particles. Due to limitations in particle size with froth flotation, and high downstream dewatering costs, a new process has been developed called the hydrophobic-hydrophilic separation (HHS) process. This process was originally based on a concept known as dewatering by displacement (DbD) which was developed by researchers at Virginia Tech in 1995. The process uses hydrocarbon oils, like pentane or heptane, to selectively collect hydrophobic particles, such as coal, for which it was originally developed. In coal preparation plants, a common practice is to purposefully discard the ultrafine stream that flotation cannot recover and has an increased dewatering cost. The HHS process can effectively recovery this waste stream and produce highgrade salable product, with significantly reduced cost of dewatering. In the work presented, laboratory-scale tests have been conducted on various coal samples with the objective of commercial deployment of the HHS process. In this respect, several varying plant streams have been tested apart from the traditional discard stream. Additionally, test work has expanded into mineral commodities such as copper and rare earth minerals. In this work, salable high-value coal products were achievable with the HHS process. Ultrafine streams consistently produced less than 10% ash and moisture. Coarse coal feeds had no observable degradation to the HHS process and were able to produce single digit ash and moisture values. Middling coal samples were upgraded to high-value coal products when micronized by grinding. All coal samples performed better with the HHS process than with flotation in terms of separation efficiency. High-grade rare earth mineral concentrates were produced with the HHS process ranging from 600- 2100 ppm of total rare earth elements depending on the method and reagent. Additionally, the HHS process produced copper concentrates assaying greater than 30% Cu for an artificial and feed samples, as well as, between 10-20% Cu for waste samples, which all performed better than flotation.
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Zhuang, Rong-Chuan. "Synthesis of polymers and oligomers containing fluorinated side groups for the construction of hydrophobic surfaces." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1120215670616-23184.
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Oligomers and polymers based on functionalized Rf-amides were successfully synthesized for the fabrication of hydrophobic surfaces with either linear or network structure. Firstly, new functionalized Rf-amides (RfCONH-, Rf is a perfluoroalkyl segment) were developed in most cases by a one step reaction and a simple work-up procedure. The reaction behaviors of synthesized Rf-amides in polyreactions were well understood. New fluorinated oligoester polyols, blocked IPDI's, and end-hydroxyl terminated oligo(urea urethane)s have been synthesized, the detail structures and properties are well understood. These materials could be suitable components of powder coatings. On the other hand, the end-hydroxyl terminated oligo(urea urethane)s could be used as reactive additives in high solid content and water-borne coatings. Hydrophobic smooth surfaces based on linear polymers, poly(urea urethane)s and alternating MI copolymers, containing fluorinated side groups were successfully constructed. The attachment of fluorinated side groups into polymers can dramatically alter the surfaces of corresponding polymers from more hydrophilic to hydrophobic due to the enrichment of fluorinated side groups on the top of the surface. The backbone configuration, the polarity of backbones, and the thermal treatment on surfaces can influence the surface properties of corresponding materials. Finally, hydrophobic surfaces of cross-linked polyurethanes as model top coatings were constructed under melt condition at high temperature (180 and 190 oC) using the combination of fluorinated oligouretdiones and non-fluorinated oligoester polyols. It was found that the hydrophobicity of resulting cured films is a matter of the competition between the formation of cross-linking network and the segregation of fluoromoieties on the top of the surface.
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Degabriel, Thomas. "Study of the interaction between proteins and TiO2 NPs : nature of the interfacial processes." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066660/document.
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L’utilisation de nanoparticules (NPs) dans un milieu biologique est de plus en plus importante, alors que leur assimilation et leur toxicité reste peu maitrisée. Dans ce contexte l’objectif de ce travail est d’étudier l’interaction entre nanoparticules de dioxyde de titane (TiO2) avec des protéines ainsi que leur possible impact sur leurs propriétés structurales. Trois protéines d’intérêt ont été choisies: une protéine de la matrice extra cellulaire, le collagène, et deux protéines du plasma sanguin, l’albumine et le fibrinogène. Le choix a été basé sur l’importance biologique de ces protéines lors des interactions avec des NPs et sur la différence de leurs structures tridimensionnelles. L’étude de l’interaction protéine-NPs a été réalisée en solution et en phase adsorbée dans différentes conditions de température et de temps d’incubation. Dans un premier temps des nanoparticules de dioxyde de titane ont été synthétisées par voie solvothermale, afin d’obtenir des nanoparticules de tailles et de formes contrôlées. Deux types de nanoparticules ont été sélectionnés en vues d’étudier l’effet de forme et de taille sur l’interaction protéines-nanoparticules: des nano-sphères de diamètre de 8 à 10 nm et des nano-bâtonnets d’environ 8 nm de largeur et 23 nm longueur. Leur comportement en solution physiologique ainsi que leur réactivité ont été caractérisé par DSL et absorption UV montrant une inhibition des propriétés catalytiques ainsi qu’une forte agrégation en solution tampon phosphate saline (PBS). Dans un deuxième temps les propriétés d’adsorption du collagène en présence de nanoparticules furent étudiées sur deux types de surfaces l’une hydrophobe et l’autre hydrophile par XPS et imagerie AFM ainsi que par des mesures de forces AFM. Le comportement du collagène en solution en présence de nanoparticules a été caractérisé par ATR liquide. Les observations suggèrent que la formation des fibrilles à l’interface surface-solution de collagène est affectée par le caractère hydrophobe ou hydrophile de la surface ainsi que par la présence de nanoparticules. Enfin les propriétés d’adsorption de la HSA et du fibrinogène en présence de nanoparticules furent étudiées sur une surface hydrophile par imagerie AFM et analyses XPS. Leur comportement en solution en présence de nanoparticules fut étudié par ATR liquide. Les résultats suggèrent deux comportements différents des protéines en présence de nanoparticules pouvant être attribués propriétés physicochimiques différentes des protéines. La HSA subit d’importants changements structuraux en présence de nanoparticules contrairement au fibrinogène.L’étude en phase liquide de l’interaction protéine-nanoparticules couplé à l’étude en phase adsorbées des protéines permet de déterminer les phénomènes impliqués lors de cette interaction ainsi que leurs conséquences sur les protéines, de plus l’utilisation de nanoparticules de taille et forme différentes permet d’étudier la sensibilité des protéines à ces facteursThe extensive use of NPs in a biological environment raises the problem of their assimilation or their toxicity, the main objective of this work is to study the interaction of TiO2 NPs with proteins as well as their possible impact on the structural properties of proteins. Three proteins were chosen, a protein of the extracellular matrix, the collagen, and two proteins of the plasma blood, the albumin and the fibrinogen for their biological importance as well as for their various tridimensional structures. The study of the protein-nanoparticle interaction was realized in solution and in the adsorbed phase under various condition of temperature and incubation time. First, titanium dioxide NPs were synthesized by a solvothermal method, NPs with controlled size and form were obtained. Two types of NPs were selected in order to study the effect of shape and size on the protein-NPs interaction: nano-spheres with a diameter of 8 to 10 nm and nano-rods with a width about 8 nm and a length of 23 nm. The behavior in physiological solution as well as the reactivity were characterized by DSL and UV absorption showing an inhibition of catalytic properties as well as a strong aggregation in phosphate buffer saline solution (PBS). Second, the adsorption properties of the collagen in the presence of NPs were studied on two kinds of surfaces, one hydrophobic and the other hydrophilic by XPS and AFM imaging as well as by AFM force measurements. The behavior of the collagen in solution in the presence of NPs was characterized by liquid ATR. The observations suggest that the formation of fibrils at the surface- collagen solution interface is affected by the hydrophobic or the hydrophilic character of the surface as well as by the presence of NPs. In the last part the adsorption properties of HSA and fibrinogen in the presence of NPs were studied on a hydrophilic surface by AFM imaging and XPS analyses. Their behaviors in solution in the presence of NPs were studied by liquid ATR. The results suggest two different behaviors of proteins in the presence of NPs, which can be attributed to the different physico-chemical properties of the proteins. HSA undergoes important structural changes in the presence of NPs but not fibrinogen. The study in the liquid phase of the protein-nanoparticle interaction, coupled to study of proteins in the adsorbed phase allows determining the involved phenomenon during the protein-nanoparticle interaction as well as the consequences on protein adsorption. Moreover, the use of NPs with different sizes and shapes revealed the sensitivity of proteins to these factors
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Nguyen, Hoang Truc Phuong. "Formulation de nanosystèmes et évaluation de leur potentiel pour la délivrance cutanée de molécules actives." Thesis, Tours, 2015. http://www.theses.fr/2015TOUR3806/document.
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Ces travaux visent à déterminer l‘intérêt de deux types de nanosystèmes (NS) coeur-couronne dans des applications dermatologiques ou cosmétiques. Les nanocapsules lipidiques (LNC) sont obtenues par une méthode déjà décrite dans la littérature. Leur formule est modifiée pour incorporer un actif cosmétique d‘intérêt. Les nanocapsules d‘alginate (ANC) sont développées au moyen de plans d‘expériences. Elles sont composées d‘un coeur huileux et d‘une coque d‘alginate de calcium gélifiée obtenue par gélification ionique de surface d‘une nanoémulsion. Des méthodes basées sur le phénomène de fluorescence nous permettent de mettre en évidence l‘endocytose des ANC par les kératinocytes. Leur contenu est rapidement libéré dans le cytoplasme. Une étude sur différents modèles ex vivo montre que les deux nanosystèmes permettent aux molécules encapsulées d‘atteindre les couches vivantes de l‘épiderme. ANC et LNC sont stables plusieurs mois dispersées dans des formes galéniques semi-solides. Ces deux NS sont donc adaptés à la délivrance de molécules actives dans la peauTwo types of core-shell nanosystems have been evaluated for dermatological and cosmetic applications. Lipid nanocapsules (LNC) are obtained by a method that has already been described in the literature. Their composition is adapted for incorporation of a specific cosmetic ingredient. Alginate nanocapsules (ANC) are developed with the aid of experimental design. They consist of a triglyceride core with a rigid calcium alginate shell obtained by ionic gelation of the surface of a nanoemulsion. By incorporating fluorophores into these nanosystems, they can be studied by advanced spectral fluorescence imaging methods. We were thus able to show that ANC are first internalized into keratinocytes by endocytosis, and once inside the cells, their contents are rapidly released into the cytoplasm. A study of different ex vivo skin model systems has shown that both nanosystems enable active substances to reach the living epidermis. When incorporated into gels similar to those used as galenic forms for topical administration, LNC and ANC remain stable for months. They can thus be used as vectors for delivering active substances to the skin
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Tchuenbou-Magaia, Fideline Laure. "Hydrophobins and air filled emulsions." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3594/.
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Suspensions of micron sized air cells, Air Filled Emulsions (AFEs), represent a new colloidal material with outstanding physical properties. They have the potential for technological applications in very different fields such as biomedical, environmental sciences and the food industry. This thesis focuses on the construction of AFEs and their use as ingredients to construct reduced fat and calorie emulsion-based products. These microstructurally complex materials have been termed triphasic A/O/W emulsions. A sonochemical templating process has allowed for the construction of air cells (the majority around 0.5-10 μm) in the size range of oil droplets found in emulsion based foods. Air cells were stabilised with either hydrophobins, obtained from submerged fermentation and extraction, or other cysteine rich but more common proteins such as bovine serum albumin (BSA) and egg albumen (EWP). The air cells were stable against disproportionation and ripening for substantial periods of time. They resisted destabilisation effect of oil droplets and could survive unit operations involving mild vacuum treatment and centrifugal forces, relatively high shear forces, temperatures and pressures. Triphasic A/O/W emulsions were created with up to 60% included phase of air and oil in an aqueous continuous phase. This gave a greater than 50% reduction in lipid content. Comparative rheology and tribology showed that the triphasic A/O/W emulsions could have similar if not better lubrication properties than a full O/W version. The molecular properties of the protein used for the AFEs played a crucial role in the determination of lubrication properties (mouth-feel). Moreover, AFEs and triphasic emulsions offer the potential for new structures and textures for the food industry due to their self interaction to give a weak gel
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Cao, Huachuan. "Part I Charge transfer in DNA containing modified guanine bases: Steric and engergetic control of reactivity : Part II Synthesis of DNA binding lipids to induce hydrophobic environment." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/30008.
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