Dissertations / Theses: 'Wettability of vegetal surfaces'

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Bami, Chatenet Yann. "Modélisation analytique du mouillage sur des topographies multi-échelles complexes pour le design biomimétique de surfaces superhydrophobes." Electronic Thesis or Diss., Ecully, Ecole centrale de Lyon, 2024. http://www.theses.fr/2024ECDL0053.

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Une goutte d’eau roule sur une feuille de lotus sacré mais elle adhère à un pétale de rose. Ces deux surfaces présentent, aux échelles micrométrique et nanométrique, une morphologie complexe. Quel est alors le lien entre leur mouillabilité et leur morphologie multi-échelles ? L’objectif de cette thèse est de mener une approche biomimétique pour la conception de surfaces superhydrophobes tout en comprenant les stratégies mises en œuvre par le vivant. Dans une première partie, nous caractérisons des surfaces végétales dont le régime de mouillage est observé directement par microscopie confocale à balayage laser. Nous démontrons que le lotus sacré produit un mouillage en régime mixte métastable caractérisable par une profondeur d’ancrage non nulle des lignes triples à l’équilibre. De plus, nous observons un régime hiérarchique de Wenzel-Wenzel sur le pétale de rose, à rebours des hypothèses de la littérature. De ces observations, nous tirons des questionnements clés que nous confrontons aux modèles actuels de la littérature. Dans une seconde partie, nous adaptons deux approches des phénomènes capillaires à l’étude du piégeage d’air sur une topographie multi-échelles et introduisons la paramétrisation nécessaire à l’étude des régimes de mouillage mixte et de leur robustesse. Nous prédisons la profondeur d’ancrage à l’équilibre sur le lotus sacré en mettant en lumière le rôle de sa topographie nanométrique. Enfin, nous décrivons les mécanismes gouvernant les mouvements à l’avancée et à la reculée et leurs propagations par récurrence à travers les échelles topographiques constituant une surface en introduisant la notion de mouvement précurseur. Nous démontrons l’effet de la profondeur d’ancrage à l’équilibre sur l’hystérèse d’angle de contact et le rôle des sous-échelles topographiques sur la robustesse du régime de piégeage d’air. À travers l’étude expérimentale de surfaces fabriquées par photolithographie, nous confrontons ce modèle à la réalité. Enfin, dans une troisième partie, nous transposons les conclusions issues de ce modèle en un cahier des charges pour la conception de surfaces superhydrophobes robustes, déclinons la stratégie mise en œuvre par la feuille du lotus sacré et proposons deux voies de fabrication de surfaces déperlantes, par recristallisation de cire naturelle et polymérisation deux-photons
A drop of water rolls on the sacred lotus leaf but stay fiercely anchored onto a rose petal. Both surfaces display a complex morphology at the micrometric and nanometric scales. Therefore, one could ask: how are their wettability and their morphology related? The purpose of this dissertation is to carry out a biomimetic approach in order to conceive superhydrophobic surfaces and to better understand nature’s strategies. In a first part, vegetal surfaces have been characterized by directly observing the wetting state they produce with the help of confocal microscopy. We demonstrate the fact that the sacred lotus produces a metastable mixed-state wetting that is characterized by a finite equilibrium anchorage depth of triple lines. On the other hand, a Wenzel-Wenzel hierarchical wetting state is observed on the rose petal, in spite of what literature suggests. From these experiments, key questions have been highlighted and confronted to the current models available within the literature. In a second part, two approaches to capillary phenomena have been adapted to the study of a composite wetting state produced by a multiscale topography. We introduce a complete parameterization allowing us to tackle the problem of the mixed-state wetting and its stability, to predict the value of the equilibrium anchorage depth on the sacred lotus leaf and to identify the contribution of its nanoscale topography to its wetting. Then, we thoroughly describe the mechanisms underlying the advancing and receding motions of triple lines and their recursive propagation across every topographical scale constituting a surface by introducing the notion of precursor motion. We highlight the effect of the equilibrium anchorage depth on the contact angle hysteresis and the role played by topographical subscales on the robustness of the composite wetting state. Through the experimental study of model surfaces manufactured by photolithography, we compare our predictions to reality. Eventually, in a third part, the conclusions drawn from our model are transposed into technical specifications for the conception of robust superhydrophobic surfaces, the strategy of the sacred lotus leaf is thoroughly described and two promising manufacturing processes are proposed through the recrystallization of natural wax and two-photon polymerization

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Melberg, Brita. "Nanostructured surfaces with patterned wettability." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19410.

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This project aims at the fabrication of a rough polydimethylsiloxane(PDMS) surface with patterned smooth areas. The idea is that such a surface will allow for water capturing on the smooth areas of the surface. The applications for this kind of surface are many, but especially the prospects of a surface able to trap droplets of cells in suspension by simply dipping the surface into the suspension is intriguing.From a previous project[1], and another student’s master’s thesis[2], the use of an etched copper surface seemed promising for the fabrication of a rough mold. This was abandoned after sandpaper turned out to be an even better mold, giving superhydrophobic PDMS(162, 33 ± 1, 40degrees).The negative photoresist SU-8 5 was used to pattern the sandpaper with small, circular features on the P1000 sandpaper(400μm and 1mm in diameter). The PDMS replica from this mold was a rough surface with smooth wells. This was not able to capture water droplets effectively, partly because air bubbles were trapped in the wells during the immersion in water. To avoid this, another mold was procured by the silanization of the previously made PDMS surface. The PDMS replica of the silanized PDMS had smooth pillars instead of wells, and did not succeed in trapping water droplets either. In fact, the smooth wells seemed to better at capturing the water.This project has succeeded in producing high enough roughness on PDMS to alter the contact angle with water by ∼ 61 degrees to a contact angle exceeding the lower limit for superhydrophobic surfaces by ∼ 12 degrees. The use of a sandpaper mold has proven to is simple, inexpensive and effective at producing PDMS with high contact angles.

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Hobæk, Thor Christian. "Nanostructured PDMS surfaces with patterned wettability." Thesis, Norges Teknisk-Naturvitenskaplige Universitet, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-21045.

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In this study, a surface with patterned wettability by means of surface structuring, rather than through modifying the surface chemistry, was developed. The device presented in this thesis was inspired by the Namib Desert Bettle, which collects water from the fog by having hydrophilic spots surrounded by hydrophobic wax-coated regions on its back. Besides water collection, controlling the wetting behaviour locally on the surface may find applications within droplet-based microfluidics, or fabrication of DNA, protein or cell microarrays. Spatial wetting contrast was achieved through replica moulding of the elastomer polydimethylsiloxane (PDMS), using a copper and/or the epoxy-based SU-8 photoresist surface as a template. Different types of surface roughness was produced and characterized on polycrystalline copper, through etching, oxidation, electrodeposition, or a combination. Regions with no surface roughness was patterned on the template moulds through conventional UV-photolithography processing of SU-8. The PDMS replicas were then tested for the ability to capture water droplets selectively on the patterned spots. Through characterization of the surface roughness by atomic force microscopy (AFM) and scanning electron microscopy (SEM), copper plates etched with a solution of CuCl2 and HCl produced the highest amount of surface roughness, with longer etching times leading to increased surface roughness. To characterize the hydrophobicity, the contact angle was measured for droplets deposited on the rough PDMS surfaces. Through surface structuring, the contact angle was increased from 101.8 ± 3.6◦ for a flat surface, to 154.7 ± 5.3◦ for the PDMS surface with the highest roughness. The polarity of surface roughness was also found to play an important role in the wetting behaviour, with a higher number of peaks than valleys being preferable. The fabricated PDMS surfaces showed spatial wetting contrast, as demonstrated in the cover photo. The device needs further optimization in terms of increasing the hydrophobicity of the rough regions, as well as changing the pattern geometries. However, the discoveries made in this study may be useful for further development and integration with droplet-moving mechanisms, for future lab-on-a-chip applications within medical diagnostics or chemical analysis.

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Badge, Ila. "Tuning Wettability And Adhesion Of Structured Surfaces." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1393716842.

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Zhang, Xueyun. "Wettability tuning by surface modification /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CBME%202009%20ZHANG.

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Falah, Toosi Salma. "Superhydrophobic polymeric surfaces : fabrication, wettability, and antibbacterial activity." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62353.

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This PhD thesis studies fabrication of superhydrophobic polymeric surfaces, their wetting properties, and their antibacterial activities as potential application to medical sciences. A femtosecond laser technique was used to fabricate mico/nano- structures on the surface of PTFE and PU. The effect of laser parameters (fluence, scanning speed, and overlap) on the wettability of the resulted micro/nano-patterns was studied. Two techniques were used to laser-scan the surface, namely uniaxial and biaxial scan. Uniaxial scan creates channeled morphology with direction-dependent wettability. To produce uniform wettability independent of direction, biaxial scanning was examined, which creates well-defined pillars with very high contact angle (CA) and very low contact angle hysteresis (CAH). To facilitate and speed up the surface micro/nano-structuring, laser-ablation was coupled with thermal imprinting. The metallic femtosecond laser-ablated templates were employed to imprint micron/submicron periodic structures onto the surface of several polymers. The CA of imprinted polymers increased to above 160°, while their CAH varied significantly depending on the surface thermophysical and chemical properties. A unique technique was developed to create superomniphobic patterns on HDPE through hot embossing. The filefish skin dual scale superoleophobic patterns were used as a biological model to develop angled microfiber arrays on HDPE. The obtained bioinspired surface is highly capable of repelling both water and liquids with low surface tensions that meets the superomniphobic criteria. The effect of superhydrophobicity on protein adsorption and bacterial adhesion of laser-ablated PTFE substrates were investigated. Samples were incubated in Gram negative (E.coli) and Gram positive (S.aureus) bacteria cultures, BSA solution, IgG solution, and blood plasma for 4 hours. All superhydrophobic surfaces were found to be more resistant to protein /bacteria adhesion compared to the corresponding smooth samples. However, some of the most superhydrophobic PTFE surfaces were found to exhibit the highest adherence with protein/bacteria; while some other did not allow any adsorption/adherence of protein/bacteria respectively towards the end of the incubation. Besides the CA, CAH, average height of pillars, and spacing distance between iii the pillars, this study showed that there are other roughness factors, which play crucial role in the durability of the superhydrophobic surfaces such as the distribution of pillar heights.
Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate

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Plaisance, Marc Charles. "Cellular Response to Surface Wettability Gradient on Microtextured Surfaces." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/53730.

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Objective: Topography, chemistry, and energy of titanium (Ti) implants alter cell response through variations in protein adsorption, integrin expression, and downstream cell signaling. However, the contribution of surface energy on cell response is difficult to isolate because altered hydrophilicity can result from changes in surface chemistry or microstructure. Our aim was to examine a unique system of wettability gradients created on microstructured Ti on osteoblast maturation and phenotype. Method: A surface energy gradient was created on sand-blasted/acid-etched (SLA) Ti surfaces. Surfaces were treated with oxygen plasma for 2 minutes, and then allowed to age for 1, 12, 80, or 116 hours to generate a wettability gradient. Surfaces were characterized by contact angle and SEM. MG63 cells were cultured on SLA or experimental SLA surfaces to confluence on TCPS. Osteoblast differentiation (IBSP, RUNX2, ALP, OCN, OPG) and integrin subunits (ITG2, ITGA5, ITGAV, ITGB1) measured by real-time PCR (n=6 surfaces per variable analyzed by ANOVA/Bonferroni’s modified Student’s t-test). Result: After plasma treatment, SLA surface topography was retained. A gradient of wettability was obtained, with contact angles of 32.0° (SLA116), 23.3° (SLA80), 12.5° (SLA12), 7.9° (SLA1). All surfaces were significantly more hydrophilic than the original SLA surface (126.8°). Integrin expression was affected by wettability. ITGA2 was higher on wettable surfaces than on SLA, but was highest on SLA1. ITGAV and ITGB1 were decreased on hydrophilic surfaces, but ITGA5 was not affected. IBSP, RUNX2, and ALP increased and OPG decreased with increasing wettability. OCN decreased with increasing wettability, but levels on the most wettable surface were similar to SLA. Conclusion: Here we elucidated the role of surface energy on cell response using surfaces with the same topography and chemistry. The results show that osteoblastic maturation was regulated in a wettability-dependent manner and suggest that the effects are mediated by integrins.

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Shirafkan, Abbas. "Wettability and hydrophilicity of rigid and soft contact lens surfaces." Thesis, City University London, 1997. http://openaccess.city.ac.uk/8385/.

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In the last two decades an abundance of contact lens materials with unknown surface properties have been introduced as well as new contact lens design. Recent studies have identified the importance of physical and chemical interactions between materials and liquids. The purpose of this experimental research work was to investigate the relationship between a contact lens surface and a liquid. The wettability and hydrophilicity of both soft and rigid contact lens surfaces were determined using two novel techniques and an established method. The two novel techniques were the un-separated adherent quid/laser method and the adherent liquid/ maximum force method whereas the established technique involved monitoring the receding wetting angle and interface are a diameter of a sessile drop. Contact lens surface preparation and the method of removing a liquid from hydrated surfaces were found to be important variables when determining wettability or hydrophilicity. Experiments showed that the use of surface tension to remove liquid from hydrated surfaces significantly improved the reproducibility of subsequent measurements. Variation of the sessile drop wetting angle and interface area diameter with evaporation time demonstrated different values for different contact lenses. The clinical consequence of monitoring the receding values would be; if a material to spread tear break up time occurs the dry patches will be advanced on PMMA, rather than Paraperm contact lens. Surface hydrophilicity, if defined in terms of the maximum adherent force, describes the ability of a lens surface to attract a liquid, whereas wettability may be defined as the ability of a liquid to spread on a contact lens surface. The wettability and hydrophilicity, therefore, are two different issues. When a wetting angle is 01, or close to 0" the surface is described as wettable. Results demonstrated that Equalens had a greater surface wettability and hydrophilicity than the PMMA for pre-wear, but the post-wear hydrophilicity for PMMA was greater than Equalens. The use of each measurement method, therefore, resulted in a value that is intrinsically related to measurement method and definition. The clinical consequenceo f the valuesi s to help practitioners prescribea lens material either on wettability or hydrophilicity values. In contact lens practice, a lens surface is required to maintain a stable tear film and produce a long tear film break up time. A combination of hydrophilicty and wetting angle values can help to determine the requirement of wettability and hydrophilicity in the contact lens industry and also in practice. It can be concluded that no single test can fully describe the surface properties of contact lens surface materials, but it is proposed that information and results from a series of tests provides the most useful clinical description.

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Sernek, Milan. "Comparative Analysis of Inactivated Wood Surfaces." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/27429.

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A wood surface, which is exposed to a high temperature condition, can experience inactivation. Surface inactivation results in reduced ability of an adhesive to properly wet, flow, penetrate, and cure. Thus, an inactivated wood surface does not bond well with adhesives. The changes in surface chemistry, wettability, and adhesion of inactivated wood surfaces, including heartwood of yellow-poplar (Liriodendron tulipifera) and southern pine (Pinus taeda), were studied. Wood samples were dried from the green moisture content condition in a convection oven at five different temperature levels ranging from 50 to 200 Â°C. The comparative characterization of the surface was done by X-ray photoelectron spectroscopy (XPS), sessile drop wettability, and fracture testing of adhesive bonds. The oxygen to carbon ratio (O/C) decreased and the C1/C2 ratio increased with drying temperature. The C1 component is related to carbon-carbon or carbon-hydrogen bonds, and the C2 component represents single carbon-oxygen bond. A low O/C ratio and a high C1/C2 ratio reflected a high concentration of non-polar wood components (extractives/VOCs) on the wood surface, which modified the wood surface from hydrophilic to more hydrophobic. Wettability was directly related to the O/C ratio and inversely related to the C1/C2 ratio. Contact angle decreased with time and increased with the temperature of exposure. Southern pine had a lower wettability than yellow-poplar, which was due to a greater concentration of non-polar hydrocarbon-type extractives and heat-generated volatiles on the surface. Solvent extraction prior to drying did not improved wettability, whereas, extraction after drying improved wettability. A contribution of extractives migration and VOCs generation played a significant role in the heat-induced inactivation process of southern pine. The maximum strain energy release rate (Gmax) showed that surface inactivation was insignificant for yellow-poplar when exposed to drying temperatures < 187Â°C. The southern pine was most susceptible to inactivation at drying temperatures > 156Â°C, particularly when bonded with phenol-formaldehyde (PF) adhesive. Chemical treatments improved the wettability of inactivated wood surfaces, but an improvement in adhesion was not evident for specimens bonded with polyvinyl-acetate (PVA) adhesive. NaOH surface treatment was most effective for improving adhesion of the PF adhesive bond.
Ph. D.

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Tow, Emily Winona. "Bubble behavior in subcooled flow boiling on surfaces of variable wettability." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/75682.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 59).
Flow boiling is important in energy conversion and thermal management due to its potential for very high heat fluxes. By improving understanding of the conditions leading to bubble departure, surfaces can be designed that increase heat transfer coefficients in flow boiling. Bubbles were visualized during subcooled nucleate flow boiling of water on a surface of variable wettability. Images obtained from the videos were analyzed to find parameters influencing bubble size at departure. A model was developed relating the dimensions of the bubble at departure to its upstream and downstream contact angles based on a rigid-body force balance between momentum and surface tension and assuming a skewed truncated spherical bubble shape. Both experimental and theoretical results predict that bubble width and height decrease with increasing flow speed and that the width increases with the equilibrium contact angle. The model also predicts that the width and height increase with the amount of contact angle hysteresis and that the height increases with equilibrium contact angle, though neither of these trends were clearly demonstrated by the data. Several directions for future research are proposed, including modifications to the model to account for deviations of the bubbles from the assumed geometry and research into the parameters controlling contact angle hysteresis of bubbles in a flow. Additionally, observations support that surfaces with periodically-varying contact angle may prevent film formation and increase the heat transfer coefficients in both film and pool boiling.
by Emily W. Tow.
S.B.

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Denison, Kieth Royston. "A study of photo-induced wettability changes at metal oxide semiconductor surfaces." Thesis, Lancaster University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.651293.

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Colloidal semiconductor photocatalytic materials such as Ti02• α-Fe203 and Sn02 have been used in laboratory-scale pollution abatement systems, reducing I oxidising both organic and inorganic impurities / toxins to chemically useful and / or biologically harmless compounds. For Ti02 there are potentially two distinct photoinduced phenomena: the first is the photocatalytic redox phenomena described above. The second involves photolytically induced high wettability or superhydrophilicity. The longer the surface is illuminated with IN light, the smaller the contact angle formed between the air - water - TiO2 interfaces until, in some cases the angle approaches zero. We have studied Photo-induced SuperHydrophilicity (PISH) on mesoporous TiO2(M-Ti02) films produced from reverse micellar solutions of titanium isopropoxide. M-Ti02 films have been deposited on quartz by spin coating and shown to clearly exhibit phot(}-induced wettability when irradiated with ultra-band gap light. Using a new continuous contact angle measurement technique. the time dependence of the photo-induced wettability changes on the film have been evaluated through the spreading of a sessile water drop. Results obtained at 100% RH, 293 K showed that drops on M-Ti02 exhibited a photo-induced "stick-slip" behaviour. The thermodynamic driving force for this photo-induced stick-slip has been attributed to the departure of the system from capillary equilibrium as the equilibrium contact angle of the drop, θo, decreased with illumination time. Based on this model, a simple theoretical description of photo-induced stick-slip has been derived and used to calculate a value of the potential energy barrier opposing the onset of movement of the triple line, U = 6.26 X 10-6 J m-1. This is the first time that U has been quantified for a surface with photo-induced wenability. Micro gravimetric studies of M-Ti02 layers in humid atmospheres show that, especially at RH > 95%, illumination of the M-Ti02 surface leads to a photo-induced watcr adsorption I condensation at the semiconductor / gas interface. Studies of this photo-induced water condensation on M-Ti02 coated crystals as a function of crystal age / experiment run number indicates that there are two possible modes of condensation - in-pore / in-layer condensation and condensation over the outer surface of the layer.

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Zhu, Geyunjian. "FABRICATION OF SLIPPERY LIQUID-INFUSED POROUS SURFACES USING LAYER-BY-LAYER ASSEMBLY: TOWARDS MULTIFUNCTIONAL SURFACES AND FACILE FABRICATION PROCESSES." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1518051453328934.

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Li, Nanxi. "High-pressure pool boiling and physical insight of engineered surfaces." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/35561.

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Doctor of Philosophy
Department of Mechanical and Nuclear Engineering
Amy R. Betz
Boiling is a very effective way of heat transfer due to the latent heat of vaporization. Large amount of heat can be removed as bubbles form and leave the heated surface. Boiling heat transfer has lots of applications both in our daily lives and in the industry. The performance of boiling can be described with two important parameters, i.e. the heat transfer coefficient (HTC) and the critical heat flux (CHF). Enhancing the performance of boiling will greatly increase the efficiency of thermal systems, decrease the size of heat exchangers, and improve the safety of thermal facilities. Boiling heat transfer is an extremely complex process. After over a century of research, the mechanism for the HTC and CHF enhancement is still elusive. Previous research has demonstrated that fluid properties, system pressures, surface properties, and heater properties etc. have huge impact on the performance of boiling. Numerous methods, both active and passive, have been developed to enhance boiling heat transfer. In this work, the effect of pressure was investigated on a plain copper substrate from atmospheric pressure to 45 psig. Boiling heat transfer performance enhancement was then investigated on Teflon© coated copper surfaces, and graphene oxide coated copper surfaces under various system pressures. It was found that both HTC and CHF increases with the system pressure on all three types of surfaces. Enhancement of HTC on the Teflon© coated copper surface is contributed by the decrease in wettability. It is also hypothesized that the enhancement in both HTC and CHF on the graphene oxide coated surface is due to pinning from micro and nanostructures in the graphene oxide coating or non-homogeneous wettability. Condensation and freezing experiments were conducted on engineered surfaces in order to further characterize the pinning effect of non-homogeneous wettability and micro/nano structure of the surface.

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Balaur, Eugeniu. "Organic monolayers on semiconductor surfaces from electron-beam induced modification to wettability control /." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=984115986.

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Zhang, Yilei. "The effect of surface roughness parameters on contact and wettability of solid surfaces." [Ames, Iowa : Iowa State University], 2007.

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Frenzel, Ralf, Christa Blank, Karina Grundke, Veneta Hein, Bernd Schmidt, Frank Simon, Michael Thieme, and Hartmut Worch. "Wettability of Methacrylate Copolymer Films Deposited on Anodically Oxidized and Roughened Aluminium Surfaces." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-107056.

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The wetting behavior of water on methacrylate copolymer films was studied on anodically oxidized and micro-roughened aluminium surfaces and also on smooth model surfaces. The copolymerization of tert-butyl methacrylate with a methacrylate containing a fluoroorganic side chain led to a considerable decrease of the surface free energy, but not to a superhydrophobic behavior of polymer-coated, micro-roughened aluminium surfaces. However, copolymers containing both hydrophobic and hydrophilic sequences are able to form superhydrophobic films. X-ray photoelectron spectroscopy showed that an enrichment of the interface between the solid phase and the air by fluorine-containing polymer components was the reason for the strong decrease of the surface free energy. The hydrophilic segments of the copolymers improved the ability to wet the highly polar aluminium surface and to form films of higher density.

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Kjemperud, Jostein. "Interaction of different crude oils with model shoreline surfaces : Adsorption and wettability studies." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemisk prosessteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22386.

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To improve shoreline cleanup operations in the current oil spill response systems, a better understanding of the interactions between the spilled crude oil and the shoreline surfaces is required. The objective of this study was to investigate how the interactions between model shorelines and different crude oils are affected by the difference in chemical composition between the oils. How long the oil has been at sea before the interaction, the weathering of the oil, was also studied. The effects of dispersants (Corexit 9500) and oil-in-seawater emulsification will also be studied.The four crude oils investigated originated from different oil fields, and had different chemical compositions. The different oil types were an asphaltic oil (from the Grane field), a waxy oil (from Norne), a naphthenic oil (from Gullfaks A) and a paraffinic oil (from Oseberg). Fresh and weathered fractions from each field were studied. The shoreline was modeled by quartz crystals with different types of coatings; silica, calcium carbonate and aluminosilicate. The parameters investigated in the study were mass adsorption of oil on the crystals, and the wettability of sea water on the oil covered crystals. The mass adsorption was measured using Quartz Crystal Microbalance with Dissipation (QCM-D), and the wettability was measured by the contact angle of seawater on the oil coated crystals using CAM 200.The results show that the asphaltic Grane oil adsorbed the most on the silica coated crystal, whilst the aluminosilicate coating tended to adsorbed more of the other oil types as well. The calcium carbonate coated crystal also adsorbed a great deal of the Grane oil, but also adsorbed the paraffinic Oseberg oil to a great extent. The dissipation measured simultaneously with the mass adsorption showed that most of the oils adsorbed as a compact and rigid layer. For the wettability of the oil types, this seemed to follow adsorption; high mass adsorption gave a low wettability of seawater on the oil covered crystals, especially for the silica and calcium carbonate coated crystals.With regards to weathering, some trends were observed. For the silica coating, the adsorption of the Norne, Oseberg and Grane oil tended to increase with increased weathering. On the aluminosilicate coating, the adsorption of the Grane oil also increased, whilst the Norne and Oseberg values decreased. For the crystals with the calcium carbonate coating, the Norne adsorption value increased, whilst the Oseberg and Grane values decreased. For all coatings, the Gullfaks A oil tended to change less than the other oil types when introduced to weatheringWhen Corexit 9500 were added, some trends were observed. The mass adsorption of the paraffinic Oseberg oil tended to decrease, whilst the asphaltic Grane oil tended to increase. The other oil types did not have as clear trends. The oil-in-seawater experiments did not give as clear tendencies as in the other experiments. The aluminosilicate coated crystals seemed to adsorb more than the other two crystal coatings, these two coatings tended to adsorb much less than in the other experiments.

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Frenzel, Ralf, Christa Blank, Karina Grundke, Veneta Hein, Bernd Schmidt, Frank Simon, Michael Thieme, and Hartmut Worch. "Wettability of Methacrylate Copolymer Films Deposited on Anodically Oxidized and Roughened Aluminium Surfaces." Technische Universität Dresden, 2009. https://tud.qucosa.de/id/qucosa%3A26713.

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The wetting behavior of water on methacrylate copolymer films was studied on anodically oxidized and micro-roughened aluminium surfaces and also on smooth model surfaces. The copolymerization of tert-butyl methacrylate with a methacrylate containing a fluoroorganic side chain led to a considerable decrease of the surface free energy, but not to a superhydrophobic behavior of polymer-coated, micro-roughened aluminium surfaces. However, copolymers containing both hydrophobic and hydrophilic sequences are able to form superhydrophobic films. X-ray photoelectron spectroscopy showed that an enrichment of the interface between the solid phase and the air by fluorine-containing polymer components was the reason for the strong decrease of the surface free energy. The hydrophilic segments of the copolymers improved the ability to wet the highly polar aluminium surface and to form films of higher density.

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He, Lingna. "Wettability Modification of Electrospun Poly(ε-caprolactone) Fiber Surfaces by Femtosecond Laser Irradiation." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1325125032.

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Abramov, Aleksandr. "Wettability of quartz surfaces under carbon dioxide geo-sequestration conditions. A theoretical study." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2019. https://ro.ecu.edu.au/theses/2232.

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The wettability of rocks under reservoir conditions is important to ensure and secure long term underground storage of carbon dioxide. The composition of those rocks vary significantly and are influenced by the fact that quartz is the second most abundant mineral in the earth's continental crust. Thus, the CO2 wettability of quartz dominates the overall CO2 trapping performance of storage and cap rocks. If depleted oil or gas reservoirs are used for storage of CO2 quartz surfaces of rocks in reservoirs which have been previously exposed to hydrocarbons might be covered with chemisorpt hydrocarbon molecules. The CO2 wettability of these chemically modified quartz is studied in this work with molecular dynamics. To model quartz surfaces with chemisorpt hydrocarbons both CLAYFF and DREIDING force fields are coupled at atomic site charge level using the density functional theory and the Bader charge analysis. Augmented with modified charges of the OC bond, CLAYFF and the DREIDING force fields are applied to solve the practical problem of calculating the contact angle of a water droplet on alkylated quartz surfaces in a CO2 environment. A systematic computational study of wettability of fully hydroxylated and alkylated (001) -quartz surface in carbon dioxide atmosphere with respect to surface concentration of pentyl groups is performed. Alkylated quartz surfaces have been shown to be extremely hydrophobic even when the surface density of hydroxyl groups is close to the highest naturally observed. The study also verifies that a comprehensive description of wettability of alkylated quartz surface requires three parameters: the theoretical contact angle, the apparent contact angle and the hidden contact angle. These contact angles are determined at the tip level of pentyl groups and the level of the quartz surface. The hidden contact angle is calculated as the angle of a water "skirt", which is formed between the level of the quartz surface and the tip level of pentyl groups. Additionally, the concept and the method of how to determine computational contact angles of a liquid droplet resting on a solid surface from individual snapshots of molecular dynamics simulations have been formulated, implemented and analysed in this work. Spherical coordinates to circumscribe a sphere around given configuration of water molecules form the basis of the method, which is thus natural and consistent with the droplet's geometric computational framework.

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Alheshibri, Muidh Hamed. "USING GRADIENTS TO MANIPULATE WATER DROPLET BEHAVIOR ON COPPER AND ALUMINUM SURFACES." Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1386599950.

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22

Park, Jung Hwa. "The role of surface chemistry and wettability of microtextured titanium surfaces in osteoblast differentiation." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44732.

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Biomaterial surface energy, chemical composition, charge, wettability and roughness all play an important role in determining the degree of the direct bone-to-implant interface, termed osseointegration. Surface chemistry, which is influenced by surface energy, wettability, and composition, is another factor that determines osteoblast phenotype and regulates osteoblast maturation. Increased surface energy is desirable for bone implants due to enhanced interaction between the implant surface and the biological environment. The extent of bone formation in vivo is also increased with increasing water wettability of implants. The physiological role of implant surface chemistry is important in determining the success of implant osseointegration because of molecular rearrangements, surface reactions, contamination, and release of toxic or biologically active ions that are determined by the starting chemistry. However, the role of surface chemistry on osteoblast response is not fully studied. Therefore, the overall goal of this dissertation is to understand how the surface chemistry, including wettability, chemical composition, and charge density, of titanium biomaterials impacts osteoblast maturation (in vitro). This study focuses on the general hypothesis that modifications of surface chemistry of titanium surfaces with sterilization or polyelectrolyte coating on titanium surfaces regulate osteoblast response.

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Zhao, Xun. "Effect of Surface Wettability, Morphology and Chemistry on the Biocompatibility of Laser Textured Titanium Surfaces." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42254.

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Titanium has been used in bio-medical implants for decades due to its superior biocompatibility. To improve the osseointegration of dental and orthopaedic implants, various surface modification techniques have been used including laser surface texturing. In particular, short-pulsed lasers, such as femtosecond and picosecond lasers, are widely used for surface modification. In this thesis, commercially pure Ti surfaces are modified by a femtosecond laser to explore the relationship between surface topography, surface chemistry, surface wettability, and biocompatibility with the goal of improving the osseointegration of implants. The laser textured surfaces consist of 1μm wide grooves spaced 10 μm, 4.8 μm, 2.4 μm and 1.2 μm apart. Gradient configurations where the groove spacing varies are also investigated. Surface morphology was characterized using Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). A custom-build contact angle measurement apparatus is used to investigate the wettability of the laser textured surfaces using the sessile drop method. Freshly laser-treated commercially pure Ti surfaces are found to be super-hydrophilic and become hydrophobic over time when exposed to air. The presence of grooves can accelerate the evolution of the contact angle over time, and introduces anisotropy in the wetting behavior (along vs. across the grooves). The hydrophilicity of laser treated surfaces can be retained by storing samples in ethanol. X-ray Photoelectron Spectroscopy (XPS) shows that the relative carbon content increases over time when Ti samples are exposed to air, which results in the subsequent evolution of the contact angle and cell response to laser textured Ti surfaces. Besides, laser treatment promotes the oxidation of pure Ti, and the product, TiO2, is responsible for the better biocompatibility. In vitro experiments using MG 63s osteoblast-like cells are implemented on laser-treated Ti surfaces and polished surfaces (control) with 1 day, 3 days and 7 days of cell culture. The best cell outcome was obtained by storing samples in air for 1 week, where storing for shorter or longer times resulted in the worst outcome, especially in the early stages of cell adhesion. There does not appear to be a direct link between wettability and the fate of cells on Ti surfaces. Indeed, while samples stored in air and ethanol have drastically different contact angle measurements (the former being hydrophobic and the latter hydrophilic), the cell behavior was unaffected. In addition, while wettability and laser treatment can affect the early stages of cell adhesion, they do not have a strong effect on the number of cells at longer incubation times (3 and 7 days). Laser machining does however affect the cell morphology and alignment, where cells preferentially align themselves parallel to the direction of the laser machined grooves with an elongated morphology.

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Parin, Riccardo. "Investigation of dropwise condensation on engineered surfaces." Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3425299.

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The scientific objective of the present thesis is to investigate dropwise condensation (DWC) over water repellant surfaces. Creation of surfaces which can promote dropwise condensation is one of the main issues. This type of surfaces, in presence of phase change, vapour-liquid or liquid-solid, can bring significant benefits to various applications, for example in thermoelectric power plant condensers, in the production of drinking water, or in applications that require defrosting for their correct operation (e.g. air source heat pumps). The research activity is focused on metallic surfaces such as aluminum and copper, as they are widely used in industry. The advantage of dropwise condensation of steam is related to the promotion of liquid droplets, which leads to higher heat transfer coefficients by one order of magnitude compared to film condensation. The development and characterization (pre and post experimental condensation tests) of several surfaces with different wettability, from hydrophilic to superhydrophobic, is presented. In particular, hydrophobic surfaces obtained via sol-gel method using hybrid organic-inorganic sol-gel silica coatings functionalized with methyl and phenyl groups are analyzed. This type of surfaces paves the way to a cheap and green route to promote stable DWC on metal substrates without using fluorocarbons or controlled roughness patterns. Indeed, the hydrophobic behavior due to methyl/phenyl groups allows to promote DWC and at the same time SiO2 represents a good barrier to chemical agents and provides resistance to mechanical stress. Condensation tests proved that, while these coatings are barely hydrophobic, exhibiting contact angles similar to untreated aluminum, condensation of steam occurs in dropwise mode reaching values of heat transfer coefficient (HTC) up to 250 kW m-2 K-1, among the highest obtained during DWC on metallic substrates, and duration of more than 100 hours with heat flux of 400 kW m-2. Furthermore, the robustness and performances of such coating at different vapor velocities, from 2.7 m s-1 to 11 m s-1, is assessed. The experimental data are compared against DWC models proposed in the past 50 years by different research groups. Such models describe the phenomena that take place during dropwise condensation: the nucleation of a droplet until its departure, the heat exchanged by the drop during its lifetime and the droplets population on the surface. The conduction through thin film (≈ 200 nm - 300 nm) is also discussed for its importance to the process. The experimental campaign is conducted at the Two-phase Heat Transfer Laboratory of the University of Padova with the collaboration of the Material Science Engineering laboratory for the surfaces development.

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Paulik, Matthew George. "The Modification of Gold Surfaces via the Reduction of Aryldiazonium Salts." Thesis, University of Canterbury. Chemistry, 2007. http://hdl.handle.net/10092/3105.

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This thesis presents the study of films derived from the reduction of aryldiazonium salts at gold surfaces. The properties of bare polycrystalline surfaces were investigated via the observation of the electrochemical oxidation and reduction of the gold. Films derived from diazonium salts were electrochemically grafted to the gold surface. The structure and stability of these interfaces was examined through the use of redox probes, gold oxide electrochemistry and water contact angle measurements. The spontaneous reduction of aryldiazonium salts at gold surfaces was investigated and the possible applications it presented towards printing and patterning of the gold surface with films were explained. Polycrystalline gold surfaces were prepared and subjected to various treatments, to observe the behaviour of gold oxide formation and reduction at the surface. Various effects on the surface structure were observed after treatment in solvents and electrolyte solutions. The surface structure of the gold atoms frequently changed due to the high mobilities of the gold atoms, and it is difficult to achieve a reproducibly stable surface. The electrochemical modification of gold surfaces via the reduction of aryldiazonium salts was investigated. Surfaces were modified with methylphenyl and carboxyphenyl films and exposed to various treatments. Monitoring the gold oxide reduction changes enabled the surface coverage of modifier directly attached to the surface to be calculated. The films appear to be stable, loosely packed and porous. The films are flexible in nature; redox probe responses showed reversible changes after repeated sonication in solvents of differing polarities and hydrophilicities. Contact angle measurements further support the notion of films that can reorganise in response to their environment. The spontaneous reduction of aryldiazonium salts at gold surfaces was observed. Film coverage was significantly lower at the spontaneously grafted surface than for films grafted electrochemically. Gold surfaces were successfully modified via microcontact printing, and surface coverages similar to the spontaneously grafted film were achieved. Microcontact printing was also used to pattern surfaces with films derived from diazonium salts. Feature sizes down to 100 µm were successfully achieved.

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Saad, Nadine. "Caractérisation par ondes acoustiques des surfaces fonctionnalisées." Phd thesis, Université de Valenciennes et du Hainaut-Cambresis, 2012. http://tel.archives-ouvertes.fr/tel-00747257.

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La fonctionnalisation des surfaces permet d'en modifier leur comportement vis-à-vis des propriétés physico-chimiques de fluides. Nous avons restreint notre étude à la caractérisation par méthode acoustique des interfaces microstructurées silicium-fluide pour lesquelles une gravure physique d'un réseau de piliers de petites dimensions a été réalisée. Les propriétés de ces interfaces vis-à-vis des liquides dépendent de la géométrie des gravures, des propriétés du fluide et des conditions d'interaction du fluide avec la surface. Notre objectif a été de confronter des modèles de comportement en terme de mouillabilité de ces surfaces aux mesures des coefficients de réflexion des ondes ultrasonores. Une première étape du travail a consisté à modéliser le coefficient de réflexion d'une onde ultrasonore incidente sur une surface microtexturée en fonction de l'état du liquide sur la surface. Deux états physiques caractéristiques ont étés étudiés : l'état où le liquide reste au sommet des piliers (état Cassie) et celui où le liquide pénètre dans le réseau de piliers (état Wenzel). Deux modèles numériques ont été développés : le premier repose sur la modélisation par éléments finis utilisant COMSOL MULTIPHYSICS et le second modèle numérique utilise une méthode explicite aux différences finies.La technique expérimentale est fondée sur une méthode de mesure du coefficient de réflexion électrique d'un transducteur ultrasonore haute fréquence à l'aide d'un analyseur de réseau, qui permet après traitement d'en déduire le coefficient de réflexion à l'interface.Les résultats originaux obtenus démontrent qu'une onde acoustique de compression est sensible à l'état d'un liquide sur une surface microtexturée.

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Raspal, Vincent. "Élaboration de surfaces nanostructurées d'alumine, caractérisation et modélisation de la mouillabilité." Thesis, Clermont-Ferrand 1, 2013. http://www.theses.fr/2013CLF1PP02/document.

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Au cours de ce travail, nous avons décrit et mis en œuvre la fabrication de surfaces nanostructurées d’alumine par anodisation de feuilles d’aluminium de très grande pureté. Les paramètres morphologiques caractérisant la membrane d’oxyde que sont le diamètre des pores, leur profondeur et leur espacement sont finement contrôlés par les paramètres expérimentaux. Ces surfaces nanotexturées ont permis l’étude approfondie de l’interaction solide-liquide au sein des pores et de la physique de la ligne de contact devant composer avec les nano-aspérités de surface. Ces deux éléments ont pu être appréhendés par des mesures d’angles de contact à l’équilibre et d’hystérésis de mouillage. La modélisation des résultats a montré l’inadéquation des modèles classiques de CASSIE, WENZEL ou de capillarité à cette situation. L’adjonction du terme controversé de tension de ligne permet de bonnes prévisions. Nous montrons que cette interprétation n’est pas unique ; une diminution de l’énergie de surface due à la forte courbure des pores conduit à des résultats identiques. Une investigation théorique a été menée par l’intégration des forces de VAN DER WAALS. La baisse de l’énergie de surface est prévue mais dans des proportions insuffisantes. Le modèle peut être amélioré. Les mesures d’hystérésis ont dévoilé le pouvoir adhésif des surfaces nanoporeuses. À cause des forces de capillarité dans les pores, la ligne de contact ne peut jamais reculer. Les angles d’avancée ont montré que la ligne de contact a une épaisseur négligeable devant la dizaine de nanomètre. Elle peut en outre parfaitement contourner les pores, imprimant de fortes courbures à l’interface liquide-gaz à la base de la goutte. Sa forme tridimensionnelle a été abordée au travers d’un modèle numérique restant à perfectionner
In this work, we have described and carried out the fabrication of nanostructured alumina surfaces by anodizing highly pure aluminum foils. The pore diameter, depth and spacing are finely controled through experimental parameters. These nanotextured surfaces allowed a thorough study of the solid-liquid interactions within the pores and of the contact-line constrained by the surface nanoasperities. Equilibrium contact-angle and wetting hysteresis measurements were helpful to apprehend them. Modeling the results has revealed the inability of classical CASSIE, WENZEL and capillarity models to properly match the situation. Adding the controversial line-tension term solves the problem and provides good predictions. Anyway, this interpretation is not unique. A lower surface energy within the pores due to their strong curvature yields the same modeling quality. This case has been theoretically investigated through the integration of VAN DER WAALS’ forces. A surface-energy decrease has been calculated but it is not as strong as required. The model still can be improved. Hysteresis measurements have highlighted the nanoporous surfaces are strongly adhesive. Because of the pore size, the capillarity is very marked and keeps the contact line from receding. The advancing contact angles have shown that the contact-line thickness is negligible with respect of ten nanometres. In addition, it can circumvent the pore openings which involves strong liquid–gas interface curvatures at the drop base. The three-dimensional liquid–gas interface shape has been studied with a numerical model that still has to be enhanced

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Virgilio, Christophe. "Caractérisation du mouillage de surfaces micro/nanostructurées par méthode acoustique haute fréquence : application aux traitements humides dans l'industrie de la microélectronique." Thesis, Valenciennes, 2017. http://www.theses.fr/2017VALE0018/document.

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L’augmentation de la densité d’intégration de composants électroniques (CMOS, FDSOI 14 nm, mémoires flash) et le développement de nouveaux dispositifs (capteurs d’images, composants photoniques) font émerger de nouveaux problèmes de fabrication des puces dans l’industrie de la microélectronique. L’efficacité des procédés humides de gravure et de nettoyage de la surface structurée des composants peut être limitée par un mouillage incomplet des micro/nanostructures dont les dimensions chutent alors que les rapports d’aspect augmentent fortement. L’état de mouillage et les cinétiques de remplissage des micro/nanostructures constituent alors deux paramètres clés pour adapter au mieux les procédés humides. Ce travail de thèse, réalisé en collaboration avec STMicroelectronics, présente une méthode acoustique originale de réflectométrie haute fréquence appliquée à la caractérisation du mouillage de surfaces structurées industrielles aux échelles micrométriques (vias) et nanométriques (tranchées profondes d’isolation de pixels, contacts de transistors CMOS). Deux modèles acoustiques ont été développés : un modèle numérique par différences finies et un modèle analytique basé sur la diffraction. Ils nous ont permis de mieux comprendre le comportement de l’onde acoustique dans les micro/nanostructures et d’interpréter les mesures expérimentales de mouillage. Nous avons alors déterminé localement l’état de mouillage des structures (état Wenzel, Cassie, composites) et détecté l’imprégnation de surfaces initialement non-mouillantes par abaissement de la tension superficielle des liquides. La cinétique de remplissage de vias micrométriques a aussi pu être mesurée
Large scale integration in the field of electronic components (CMOS, FDSOI 14 nm, flash memory), and the development of new devices (image sensors, photonic components) raise new issues in chip manufacturing in the microelectronics industry. Wet etching and wet cleaning efficiency of the patterned surface of the components can be limited by an incomplete wetting of the micro/nanostructures, for which dimensions shrink and aspect ratios increase highly. Wetting state and micro/nanostructures filling kinetics are then two key parameters to adapt the wet processes at best. This thesis work, conducted in partnership with STMicroelectronics, presents an original acoustic method of high frequency reflectometry for wetting characterization of industrial structured surfaces at the micrometric (vias) and nanometric scale (deep trenches for pixels insulation, CMOS transistor contacts). Two acoustic models have been developed: one numerical finite difference model and one analytical model based on diffraction. They enable us to have a better understanding of the acoustic wave behavior inside the micro/nanostructures and to interpret the experimental measurements of wetting. We determined the wetting state of the structures (Wenzel, Cassie, composite states) and imbibition of initially non-wetting surfaces has been detected by lowering the surface tension of the liquids. Micrometric vias filling kinetics has also been measured

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Gagnon, Yancie. "Étude de l’extraction des huiles végétales en milieu aqueux assistée par des tensioactifs." Thesis, Compiègne, 2021. http://www.theses.fr/2021COMP2654.

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L’une des préoccupations actuelles majeures des acteurs de la trituration repose sur l’identification d’une alternative au procédé utilisant l’hexane en raison de son impact sur l’environnement, la qualité des produits et la santé humaine. L’utilisation de l’eau comme solvant de substitution présente plusieurs avantages, mais cette piste a été longtemps écartée en raison de la non miscibilité de l’eau et des huiles. La solution proposée suggère d’utiliser une solution aqueuse de tensioactifs permettant la réduction de la tension interfaciale entre l’eau et l’huile sous les 10-2 mN/m (i.e. la formation de microémulsion). Cette thèse vise donc à étudier l’extraction des huiles végétales à partir de graines oléagineuses en milieux aqueux en présence de tensioactifs. L’objectif principal est d’acquérir une meilleure compréhension des mécanismes mis en jeu et notamment des interactions physicochimiques entre les différents composés du système. Différentes questions ont été abordées dans cette thèse de façon à prendre en considération pas à pas le rôle et l’impact de chaque constituant du système. D’abord, la caractérisation physicochimique de différents types de tensioactifs, en particulier les tensioactifs dits rallongés et les tensioactifs biosourcés largement moins étudiés dans la littérature, a permis de sélectionner ceux capables de solubiliser un maximum d’huile végétale dans l’eau. Ensuite, les systèmes étudiés se complexifient par la prise en compte des graines oléagineuses, et donc de l’interface solide-liquide jamais étudiée dans la littérature. Des hypothèses quant aux mécanismes d’action des tensioactifs sur la modification de la mouillabilité des surfaces oléagineuses ont pu être proposées. Finalement, l’étude du procédé d’extraction a été abordée. L’influence des paramètres opératoires sur les rendements d’extraction a été appréhendée. Les résultats obtenus offrent des perspectives de poursuite, dans le but d’envisager l’émergence de cette technologie à l’échelle industrielle
One of the major current concerns in the crushing industry is to identify an alternative to the processthat uses hexane because of its impact on the environment, product quality, and human health. Theuse of water as a substitute solvent has several advantages, but this path has long been set apart dueto the immiscibility of water and oils. The proposed solution suggests using an aqueous solution ofsurfactants allowing the reduction of the interfacial tension between water and oil below 10-2 mN/m(i.e., the formation of microemulsion). This thesis, therefore, aims to study the extraction of vegetable oils from oilseeds in aqueous media in the presence of surfactants. The main objective is to acquire a better understanding of the mechanisms involved, in particular, the physicochemical interactions between the different compounds of the system. Different questions have been addressed in this thesis to consider step by step the role and the impact of each constituent of the system. First, the physicochemical characterization of different types of surfactants, in particular, the so-called extended surfactants and bio-based surfactants that are largely less studied in the literature, which made it possible to select those capable of solubilizing a maximum of vegetable oil in water. Then, the studied systems become more complex by considering the oilseeds, therefore the solid-liquid interface, which has never been studied inthe literature. Hypotheses as to the mechanisms of action of surfactants on the wettabilitymodification of oleaginous surfaces have been proposed. Finally, the study of the extractionprocess was approached. The influence of the operating parameters on the extraction yields hasbeen apprehended. The results obtained offer prospects for further action to consider the emergenceof this technology on an industrial scale

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Sharfeddin, Asma Sharfeddin. "Mechanotransduction of Matrix Stiffness Regulates Cell Adhesion Strength: An Analysis Using Biomaterial Surfaces with Tunable Mechanical and Chemical Properties." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6387.

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Cells have the ability to sense the rigidity of the extracellular matrix which directly affects the control of cellular functions in development, wound healing and malignant transformation. Polydimethylsiloxane elastomers are useful model biomaterials for mechanotransduction studies because they possess several advantages including ease of fabrication, tunable elasticity and modifiable surface chemistry. In this work, we are investigating the influence of matrix stiffness on adhesion strength and the mechanosensory structures that regulate these processes. In addition, the effect of surface modifications to this elastic substrate system on other physical properties such as local stiffness and topography will be analyzed. Based on previous research, we hypothesized that cell adhesion dependent processes will be regulated by matrix stiffness, but that surface chemistry influences on protein adsorption could provide overriding regulatory signals. The results of this research will provide insight into the interconnected processes of mechanosensing and cell adhesion strengthening, and reveal criteria for designing instructive biomaterials with specific mechanical and chemical properties.

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Diawara, Jules. "Mouillabilité de surfaces hétérogènes (fer/oxyde) par un alliage de zinc liquide." Phd thesis, Ecole Centrale Paris, 2011. http://tel.archives-ouvertes.fr/tel-00658768.

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Le phénomène de mouillage intervient dans de nombreux procédés, parmi lesquels la galvanisation en continu de tôles d'acier pour carrosserie automobile. Dans ce procédé, la tôle est immergée dans un bain de zinc liquide afin de la recouvrir d'une couche protectrice de zinc. Mais avant cela, cette tôle, laminée à froid, est soumise à un recuit sous atmosphère réductrice dans le but d'éliminer l'écrouissage et les oxydes de fer superficiels et favoriser ainsi les réactions de galvanisation. Des nouveaux aciers, dits à haute limite d'élasticité, ont été élaborés afin d'améliorer la sécurité passive des véhicules sans trop augmenter leur masse et leur consommation de carburant. Ces aciers contiennent des teneurs élevées en éléments d'addition oxydables qui, lors du recuit, diffusent de la masse de l'acier vers la surface où ils forment des particules d'oxydes qui ne sont pas mouillées par le zinc liquide. Il parait donc important de comprendre le mouillage par le zinc liquide de surfaces hétérogènes, composées de fer métallique et d'oxydes. Pour cela, nous avons étudié l'étalement d'une goutte de zinc liquide, à des temps très courts, à l'aide d'une caméra rapide dans un dispositif de chute de goutte. Nous avons mené nos expériences sur des alliages fer - silicium et un acier industriel, recuits à haute température avant le dépôt de la goute, ce qui a permis d'obtenir un taux de couverture par les oxydes variant de 0 à 100%. Le mouillage est décrit à l'aide de deux paramètres : le diamètre d'étalement et l'angle de contact. Nous nous sommes attachés à la compréhension et à la modélisation de l'évolution de ces deux paramètres aux cours des premiers instants de contact et en fin d'étalement. Nous avons, en particulier, mis en évidence l'influence du taux de couverture par les oxydes et de l'énergie cinétique initiale de la goutte. Le manuscrit se termine par une extrapolation des résultats de mouillage obtenus pour les surfaces hétérogènes modèles à des substrats recuits dans des conditions voisines du recuit continu industriel

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O'Hanley, Harrison Fagan. "Separate effects of surface roughness, wettability and porosity on boiling heat transfer and critical heat flux and optimization of boiling surfaces." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78208.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering; and, (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 157-161).
The separate effects of surface wettability, porosity, and roughness on critical heat flux (CHF) and heat transfer coefficient (HTC) were examined using carefully-engineered surfaces. All test surfaces were prepared on nanosmooth indium tin oxide - sapphire heaters and tested in a pool boiling facility in MIT's Reactor Thermal Hydraulics Laboratory. Roughness was controlled through fabrication of micro-posts of diameter 20[mu]m and height 15[mu]m; intrinsic wettability was controlled through deposition of thin compact coatings made of hydrophilic SiO₂ (typically, 20nm thick) and hydrophobic fluorosilane (monolayer thickness); porosity and pore size were controlled through deposition of layer-by-layer coatings made of SiO₂ nanoparticles. The ranges explored were: 0 - 15[mu] for roughness (Rz), 0 - 135 degrees for intrinsic wettability, and 0 - 50% and 50nm for porosity and pore size, respectively. During testing, the active heaters were imaged with an infrared camera to map the surface temperature profile and locate distinct nucleation sites. It was determined that wettability can play a large role on a porous surface, but has a limited effect on a smooth non-porous surface. Porosity had very pronounced effects on CHF. When coupled with hydrophilicity, a porous structure enhanced CHF by approximately 50% - 60%. However, when combined with a hydrophobic surface, porosity resulted in a reduction of CHF by 97% with respect to the reference surface. Surface roughness did not have an appreciable effect, regardless of the other surface parameters present. Hydrophilic porous surfaces realized a slight HTC enhancement, while the HTC of hydrophobic porous surfaces was greatly reduced. Roughness had little effect on HTC. A second investigation used spot patterning aimed at creating a surface with optimal characteristics for both CHF and HTC. Hydrophobic spots (meant to be preferential nucleation sites) were patterned on a porous hydrophilic surface. The spots indeed were activated as nucleation sites, as recognized via the IR signal. However, CHF and HTC were not enhanced by the spots. In some instances, CHF was actually decreased by the spots, when compared to a homogenous porous hydrophilic surface.
by Harrison Fagan O'Hanley.
S.B.
S.M.

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Balu, Balamurali. "Plasma processing of cellulose surfaces and their interactions with fluids." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31675.

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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Breedveld, Victor; Committee Chair: Hess, Dennis; Committee Member: Aidun, Cyrus; Committee Member: Deng, Yulin; Committee Member: Singh, Preet. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Ben, Ali Imed Eddine. "Wetting, Adhesion and friction investigations of hetero-chemical smooth patterned surfaces." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1250/document.

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Les surfaces texturées sont devenues, ces dernières années, des substrats de choix pour de nombreuses applications. En effet, la texturation des surfaces, de l'échelle nanométrique à l'échelle microscopique, permet d'accroître les propriétés d'adhérence ou de renforcer la résistance mécanique intrinsèque. Dans ce travail de thèse nous proposons une étude sur l'influence des textures chimiques sur le comportement tribologique, adhésif et sur la mouillabilité des substrats. Dans le premier chapitre, on propose une stratégie de micro-texturation des surfaces basées sur la technique de microcontact-printing et le greffage de chaînes de polymères de géométries/formes contrôlées. En outre, on a notamment étudié de manière approfondie la mouillabilité des surfaces texturées afin de comprendre les effets de diminution de taille des textures sur le comportement adhésif. Dans les expériences d'adhésion et frottement, un dispositif de type JKR (pour Johnson, Kendall et Roberts), une machine de frottement et une FFM ont été utilisés permettant d'observer le contact entre une sphère élastique et une pointe rigide avec un plan texturé tout en contrôlant la force entre les surfaces. En outre l'utilisation de ces différentes approches ne nous a pas finalement donné des explications satisfaisantes sur les mécanismes agissant sur les phénomènes interfaciaux. De ce fait, l'utilisation du démouillage de films minces de PS et de PDMS sur des surfaces texturées nous as permis de suivre l'évolution de l'instabilité du bourrelet à l'interface. Enfin, dans le dernier chapitre, nous avons étudier les différents aspects prédominants des phénomènes interfaciaux sur des surfaces homogènes
Micro and Nanoscale surface patterns are considered as potential templates and building blocks for Micro/nanotechnology. As for materials in general, these micro /nano-scale surface structures have been of increasing research interest in recent years, due to their unique properties. They are expected to exhibit novel and significantly improved physical, chemical, mechanical and other properties, as well as to offer opportunities for manifestation of new phenomena and processes. In the present PhD work, we propose a multiple scale analysis of the adhesion, friction and wetting behaviors for different patterned interfaces. In a first chapter, we developed a general methodology to design well-defined surfaces combining micro-contact printing (µCP), self-assembled monolayers (SAMs) and polymer grafting techniques. Then we study the wettability of a patterned solid surface. Where, the stick-slip regime, and the effect of the patterning at the mesoscale was investigated. Furthermore, we concentrate on the dependence of adhesion and friction between a polymer and a rigid tip on the composition of the patterned substrates using a JKR, FFM and friction machines. Intriguingly, the uses of these approaches did not provide us with a clear answer to our bewilderment. Therefore, in the third chapter, we adopted the approach of the dewetting of thin polymer film on top of patterned surfaces. We study the impact of the solid/liquid boundary condition on the evolution of the rim instability during the course of dewetting. The last chapter details the investigation of the predominant aspect between the chemistry introduced on the surface and the mechanical proprieties of the substrate

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35

Keska, Renata. "Study of the phase behavior of poly(n-alkyl methacrylate-b-methyl methacrylate) diblock copolymers and its influence on the wettability of polymer surfaces." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1169916108434-40600.

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In this thesis detailed investigations of the phase behavior of poly(n-alkyl methacrylate-b-methyl methacrylate) diblock copolymers and its influence on the wettability of the polymer surfaces were carried out. For this investigation two polymethacrylic systems differing only in the alkyl rest of one block: poly(pentyl methacrylate-b-methyl methacrylate) and poly(propyl methacrylate-b-methyl methacrylate) have been chosen in order to prove how this substituent affects the phase behavior of whole system. The PnAlkMA-b-PMMA diblock copolymers in a wide range of molar masses, and with varied block length ratios were synthesized by living anionic polymerization. The syntheses were carried out in tetrahydrofuran (THF), at –78 °C, by using sec-buthyllithium as initiator, in the presence of lithium chloride (LiCl). Under these conditions highly syndiotactic products, rr ~ 0.82, with very narrow molar mass distribution, Mw/Mn ~ 1.1, were obtained. The phase behavior of PnAlkMA-b-PMMA diblock copolymers in bulk was investigated by means of DSC and SAXS measurements. The DSC analysis revealed that the PPMA-b-PMMA with weight fractions of PPMA, fPPMA, from 0.28 up to 0.86 showed two separate Tg’s, indicative of a phase separated system. However, by comparing the Tg’s of the diblock copolymers with the Tg’s of the corresponding homopolymers we found that in a few cases, mostly for samples with the high molar masses, they were slightly shifted. This finding pointed out the existence of two mixed phases, and hence partial miscibility between the both blocks was assumed. The SAXS patterns reflected for most diblock copolymers lamellae morphologies even in the case of very asymmetric composition, for instance with volume fraction of PPMA, 0.86 It was assumed that this behavior is caused by the chemical similarity of both blocks as well as by the differences in their molar volumes. The SAXS findings were further confirmed by the AFM measurements on the cutted “bulk” samples. From the solubility concept of Van Krevelen we obtained that the interaction parameter of PPMA-b-PMMA is rather low, 0.065, compared to the other well-known diblock copolymers. The calculated spinodals are characterized by a high asymmetry. The investigation of the phase behavior of PPMA-b-PMMA in thin films showed that the morphology as well as the topography of the thin films were strongly affected by the film thickness, when the films were prepared from a non-selective solvent (THF) onto silicon wafers. Well-recognizable nanostructures with long-range order were mainly found in thin films of diblock copolymers with high molar masses, above 100,000 g/mol, and with a high amount of PPMA. The lateral domain spacing obtained for these films from AFM corresponded well with that found in bulk. The study of the influence of the thermal as well as vapor annealing on the morphology and topography of the thin films provided additional information about the phase behavior of PPMA-b-PMMA diblock copolymers in thin films. Finally, the wettability of the investigated PPMA-b-PMMA surfaces was established by means of contact angle measurements. The measured contact angles were in most cases even on nicely nanostructured surfaces very similar to the contact angle of PPMA, indicating preferential segregation of PPMA to the film surface. Additional XPS measurements also showed an enrichment of the PPMA at the surface, independent of the morphology observed by AFM, and thereby confirmed the ADSA finding. In the next part of this work, investigations of the phase behavior of PPrMA-b-PMMA diblock copolymers were presented. In the contrary to the previous system the PPrMA-b-PMMA showed mostly a single Tg, which was further found to be depend on the weight fraction of PPrMA, fPPrMA. The SAXS data revealed that the PPrMA-b-PMMA diblock copolymers were phase separated in bulk, however the obtained scattering patterns exhibited mostly broad, not-well discernible higher-order peaks. Nevertheless, it was possible to identify the formed morphologies and depending on the volume fraction of PPrMA, hexagonally packed cylinders and lamellae were detected. The PPrMA-b-PMMA is characterized by a significantly lower value of the interaction parameter, 0.022, than the PPMA-b-PMMA system. This difference clearly reflects the weakening of the interactions between the components with decrease of the length of the alkyl side chain. The thin films of PPrMA-b-PMMA diblock copolymers appeared mostly smooth and featureless, independent of the film thickness. From the contact angle and XPS measurements we obtained, that unlike the PPMA-b-PMMA, both components were always present on the top of the surface
In der vorliegenden Arbeit wurden Untersuchungen zum Entmischungsverhalten von Poly(n-alkylmethacrylat-b-methylmethacrylat) Diblockcopolymeren und deren Einfluss auf die Benetzbarkeit der Polymeroberflächen dargestellt. Diese Untersuchungen wurden anhand der Poly(pentylmethacrylat-b-methylmethacrylat) und Poly(propylmethacrylat-b-methylmethacrylat) durchgeführt. Die Diblockcopolymere in einem weiten Molmassenbereich, mit enger Molmassenverteilung, abgestuften Zusammensetzung wurden erfolgreich mittels anionischer Polymerization synthetisiert. Die Synthese erfolgte in THF bei (-78 °C) in Gegenwart von Lithiumchlorid. Als Initiator wurde sec. Butyllithium genutzt. Das Phasenverhalten der Diblockcopolymere im Festkörper wurde mittels DSC und SAXS untersucht. Für die meiste PPMA-b-PMMA Diblockcopolymere wurden mittels DSC zwei getrennte Tg gefunden, die aber im Vergleich zu den Tg von den entsprechenden Homopolymeren leicht verschoben waren. Es wurde also eine partielle Mischbarkeit der Blöcke festgestellt. Mittels SAXS-Untersuchungen wurde für die Mehrzahl der Diblckcopolymere in einem weiten Zusammensetzungsbereich bis zum 0.86 Volumenanteil von PPMA, eine lamellare Anordnung beobachten. Diese Befunde wurden nachfolgend mit AFM–Untersuchungen an dünnen Polymerfolien bestätigt. Das mit der Mean-Filed-Methode berechnete Phasendiagramm zeigte eine Asymmetrie, die durch die Unterschiede in den molaren Volumina des Blöckes verursacht war. Es wurde aber eine gute Übereinstimmung mit der experimentell erhaltenen Daten gefunden. Der berechnete für das System Wechselwirkungsparameter beträgt 0,065. Die AFM-Untersuchungen zum Entmischungsverhalten in dünnen Filmen haben gezeigt, dass die Topographie als auch Morphologie des Films war von der Filmdicke beeinflusst. Die Polymerfilme wurden mittels dipcoating der Si-Wafer präpariert. Dazu wurden Polymerlösungen in THF verwendet. Reguläre Nanostrukturen, deren Abstände mit dem im Festkörper gefundenen sehr gut übereinstimmten, wurden bei den Proben mit höherem Anteil von PPMA erhalten. Es wurden auch der Einfluss der Temperatur und der Dampfbehandlung auf die Morphologie und Topographie des Films untersucht. Die Benetzbarkeit der untersuchte PPMA-b-PMMA Filme wurde mit der Kontaktwinkelmessungen (ADSA) bestimmt. Als Messflüssigkeit wurde Milipore Wasser genutzt. Für die Mehrzahl der Diblockcopolymere wurden Kontaktwinkel im Bereich um 95° ermitteln, unabhängig von der Zusammensetzung der Diblockcopolymere und der vorhandenen Nanostruktur. Dies entspricht dem Kontaktwinkel von PPMA Homopolymer. Die Benetzbarkeit der PPMA-b-PMMA Filme wurde also durch die Oberflächensegregation des Niedrigenergieblocks (PPMA) bestimmt. Dies wurde danach durch zusätzliche XPS Messungen bestätigt. Im Vergleich zu PPMA-b-PMMA, die nachfolgend untersuchte PPrMA-b-PMMA Diblockcopolymere wiesen eine höhere Tendenz zur Mischbarkeit auf. Anhand der DSC–Untersuchungen wurde hier vorübergehend eine Misch-Tg gefunden. Nur bei der Probe mit symmetrischer Zusammensetzung wurden zwei getrennte Tg beobachtet. Die Streukurven von diesem System waren sehr schwach ausgeprägt. Dadurch die Indizierung der vorhandenen Morphologien war nicht eindeutlich. Der berechnete Wechselwirkungsparameter beträgt 0,022. Bei den AFM-Untersuchungen zum Entmischungsverhalten in dünnen PPrMA-b-PMMA Filmen wurden entweder keine oder sehr schwach geordnete Nanostruktur gefunden. Im Gegensatz zu dem vorherigen System, die Benetzbarkeit der PPrMA-b-PMMA Filme war durch die Zusammensetzung der Diblockcopolymere bedingt

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36

Keska, Renata. "Study of the phase behavior of poly(n-alkyl methacrylate-b-methyl methacrylate) diblock copolymers and its influence on the wettability of polymer surfaces." Doctoral thesis, Technische Universität Dresden, 2006. https://tud.qucosa.de/id/qucosa%3A25029.

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In this thesis detailed investigations of the phase behavior of poly(n-alkyl methacrylate-b-methyl methacrylate) diblock copolymers and its influence on the wettability of the polymer surfaces were carried out. For this investigation two polymethacrylic systems differing only in the alkyl rest of one block: poly(pentyl methacrylate-b-methyl methacrylate) and poly(propyl methacrylate-b-methyl methacrylate) have been chosen in order to prove how this substituent affects the phase behavior of whole system. The PnAlkMA-b-PMMA diblock copolymers in a wide range of molar masses, and with varied block length ratios were synthesized by living anionic polymerization. The syntheses were carried out in tetrahydrofuran (THF), at –78 °C, by using sec-buthyllithium as initiator, in the presence of lithium chloride (LiCl). Under these conditions highly syndiotactic products, rr ~ 0.82, with very narrow molar mass distribution, Mw/Mn ~ 1.1, were obtained. The phase behavior of PnAlkMA-b-PMMA diblock copolymers in bulk was investigated by means of DSC and SAXS measurements. The DSC analysis revealed that the PPMA-b-PMMA with weight fractions of PPMA, fPPMA, from 0.28 up to 0.86 showed two separate Tg’s, indicative of a phase separated system. However, by comparing the Tg’s of the diblock copolymers with the Tg’s of the corresponding homopolymers we found that in a few cases, mostly for samples with the high molar masses, they were slightly shifted. This finding pointed out the existence of two mixed phases, and hence partial miscibility between the both blocks was assumed. The SAXS patterns reflected for most diblock copolymers lamellae morphologies even in the case of very asymmetric composition, for instance with volume fraction of PPMA, 0.86 It was assumed that this behavior is caused by the chemical similarity of both blocks as well as by the differences in their molar volumes. The SAXS findings were further confirmed by the AFM measurements on the cutted “bulk” samples. From the solubility concept of Van Krevelen we obtained that the interaction parameter of PPMA-b-PMMA is rather low, 0.065, compared to the other well-known diblock copolymers. The calculated spinodals are characterized by a high asymmetry. The investigation of the phase behavior of PPMA-b-PMMA in thin films showed that the morphology as well as the topography of the thin films were strongly affected by the film thickness, when the films were prepared from a non-selective solvent (THF) onto silicon wafers. Well-recognizable nanostructures with long-range order were mainly found in thin films of diblock copolymers with high molar masses, above 100,000 g/mol, and with a high amount of PPMA. The lateral domain spacing obtained for these films from AFM corresponded well with that found in bulk. The study of the influence of the thermal as well as vapor annealing on the morphology and topography of the thin films provided additional information about the phase behavior of PPMA-b-PMMA diblock copolymers in thin films. Finally, the wettability of the investigated PPMA-b-PMMA surfaces was established by means of contact angle measurements. The measured contact angles were in most cases even on nicely nanostructured surfaces very similar to the contact angle of PPMA, indicating preferential segregation of PPMA to the film surface. Additional XPS measurements also showed an enrichment of the PPMA at the surface, independent of the morphology observed by AFM, and thereby confirmed the ADSA finding. In the next part of this work, investigations of the phase behavior of PPrMA-b-PMMA diblock copolymers were presented. In the contrary to the previous system the PPrMA-b-PMMA showed mostly a single Tg, which was further found to be depend on the weight fraction of PPrMA, fPPrMA. The SAXS data revealed that the PPrMA-b-PMMA diblock copolymers were phase separated in bulk, however the obtained scattering patterns exhibited mostly broad, not-well discernible higher-order peaks. Nevertheless, it was possible to identify the formed morphologies and depending on the volume fraction of PPrMA, hexagonally packed cylinders and lamellae were detected. The PPrMA-b-PMMA is characterized by a significantly lower value of the interaction parameter, 0.022, than the PPMA-b-PMMA system. This difference clearly reflects the weakening of the interactions between the components with decrease of the length of the alkyl side chain. The thin films of PPrMA-b-PMMA diblock copolymers appeared mostly smooth and featureless, independent of the film thickness. From the contact angle and XPS measurements we obtained, that unlike the PPMA-b-PMMA, both components were always present on the top of the surface.
In der vorliegenden Arbeit wurden Untersuchungen zum Entmischungsverhalten von Poly(n-alkylmethacrylat-b-methylmethacrylat) Diblockcopolymeren und deren Einfluss auf die Benetzbarkeit der Polymeroberflächen dargestellt. Diese Untersuchungen wurden anhand der Poly(pentylmethacrylat-b-methylmethacrylat) und Poly(propylmethacrylat-b-methylmethacrylat) durchgeführt. Die Diblockcopolymere in einem weiten Molmassenbereich, mit enger Molmassenverteilung, abgestuften Zusammensetzung wurden erfolgreich mittels anionischer Polymerization synthetisiert. Die Synthese erfolgte in THF bei (-78 °C) in Gegenwart von Lithiumchlorid. Als Initiator wurde sec. Butyllithium genutzt. Das Phasenverhalten der Diblockcopolymere im Festkörper wurde mittels DSC und SAXS untersucht. Für die meiste PPMA-b-PMMA Diblockcopolymere wurden mittels DSC zwei getrennte Tg gefunden, die aber im Vergleich zu den Tg von den entsprechenden Homopolymeren leicht verschoben waren. Es wurde also eine partielle Mischbarkeit der Blöcke festgestellt. Mittels SAXS-Untersuchungen wurde für die Mehrzahl der Diblckcopolymere in einem weiten Zusammensetzungsbereich bis zum 0.86 Volumenanteil von PPMA, eine lamellare Anordnung beobachten. Diese Befunde wurden nachfolgend mit AFM–Untersuchungen an dünnen Polymerfolien bestätigt. Das mit der Mean-Filed-Methode berechnete Phasendiagramm zeigte eine Asymmetrie, die durch die Unterschiede in den molaren Volumina des Blöckes verursacht war. Es wurde aber eine gute Übereinstimmung mit der experimentell erhaltenen Daten gefunden. Der berechnete für das System Wechselwirkungsparameter beträgt 0,065. Die AFM-Untersuchungen zum Entmischungsverhalten in dünnen Filmen haben gezeigt, dass die Topographie als auch Morphologie des Films war von der Filmdicke beeinflusst. Die Polymerfilme wurden mittels dipcoating der Si-Wafer präpariert. Dazu wurden Polymerlösungen in THF verwendet. Reguläre Nanostrukturen, deren Abstände mit dem im Festkörper gefundenen sehr gut übereinstimmten, wurden bei den Proben mit höherem Anteil von PPMA erhalten. Es wurden auch der Einfluss der Temperatur und der Dampfbehandlung auf die Morphologie und Topographie des Films untersucht. Die Benetzbarkeit der untersuchte PPMA-b-PMMA Filme wurde mit der Kontaktwinkelmessungen (ADSA) bestimmt. Als Messflüssigkeit wurde Milipore Wasser genutzt. Für die Mehrzahl der Diblockcopolymere wurden Kontaktwinkel im Bereich um 95° ermitteln, unabhängig von der Zusammensetzung der Diblockcopolymere und der vorhandenen Nanostruktur. Dies entspricht dem Kontaktwinkel von PPMA Homopolymer. Die Benetzbarkeit der PPMA-b-PMMA Filme wurde also durch die Oberflächensegregation des Niedrigenergieblocks (PPMA) bestimmt. Dies wurde danach durch zusätzliche XPS Messungen bestätigt. Im Vergleich zu PPMA-b-PMMA, die nachfolgend untersuchte PPrMA-b-PMMA Diblockcopolymere wiesen eine höhere Tendenz zur Mischbarkeit auf. Anhand der DSC–Untersuchungen wurde hier vorübergehend eine Misch-Tg gefunden. Nur bei der Probe mit symmetrischer Zusammensetzung wurden zwei getrennte Tg beobachtet. Die Streukurven von diesem System waren sehr schwach ausgeprägt. Dadurch die Indizierung der vorhandenen Morphologien war nicht eindeutlich. Der berechnete Wechselwirkungsparameter beträgt 0,022. Bei den AFM-Untersuchungen zum Entmischungsverhalten in dünnen PPrMA-b-PMMA Filmen wurden entweder keine oder sehr schwach geordnete Nanostruktur gefunden. Im Gegensatz zu dem vorherigen System, die Benetzbarkeit der PPrMA-b-PMMA Filme war durch die Zusammensetzung der Diblockcopolymere bedingt.

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37

Berthet, Guillaume. "Revêtements diamant pour surfaces actives sur capteurs du domaine pétrolier." Electronic Thesis or Diss., Paris 6, 2017. http://www.theses.fr/2017PA066660.

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Dans le domaine pétrolier les alliages de nickel tels que l’Inconel sont majoritairement utilisés au cours des forages pour leur bonne résistance mécanique et chimique face à H2S, CO2 ou des acides carboxyliques. Cependant, en dépit de leurs excellentes propriétés, les parties sensibles des capteurs réalisés à partir de ces matériaux voient leurs performances altérées par les environnements hostiles de forages (conditions hautes pressions et hautes températures), la corrosion et l’abrasion. De plus, ces capteurs peuvent être exposés à divers fluides, durant un même forage, contenant des particules solides ou de très grosses molécules organiques telles que les asphaltènes, paraffines ou résines qui ont tendance à s’agglomérer sur les surfaces hydrophiles métalliques. Le diamant a été identifié comme un excellent candidat pour la fabrication de revêtements de protection pour des capteurs embarqués lors de forages pétroliers. En effet, le diamant offre une excellente résilience mécanique, une grande inertie chimique, un module d’Young élevé et une résistance à l’encrassement qui font de lui un matériau parfaitement adapté pour une utilisation en conditions hostiles. Cependant la réalisation d’un dépôt de diamant sur Inconel ne peut pas être réalisée via les solutions usuelles de MP-CVD. Les résultats de cette étude présentent trois différents procédés permettant d’obtenir un revêtement diamant adhérent sur des pièces 3D d’Inconel718. Ces procédés se différencient par leur rugosité et leur complexité de mise en œuvre. Leurs bénéfices sur des capteurs de densité-viscosité ont été évalués face à divers fluides pétroliers particulièrement encrassants. Pour lutter contre ces encrassements, deux approches ont été identifiées comme étant prometteuses : (i) développer des surfaces exploitant l’effet Lotus en réalisant une microstructure superhydrophobe, et (ii) optimiser un traitement électrochimique permettant de nettoyer des surfaces in-situ sans intervention humaine. Cette étude a permis de comprendre les mécanismes réactionnels en mettant en avant le rôle de la dégradation de l’eau lors du traitement électrochimique. Grace à cela, ces travaux indiquent les conditions d’utilisations et les limites du procédé. De plus le potentiel de cette technique face à des fluides de forage et du pétrole brut a été démontré avec succès
In the field of oil and gas industry, Inconel alloys are largely used for their high strength and good corrosion resilience to H2S, CO2 and carboxylic acids. However, those of despite their excellent properties compare to other alloys, some specific oil and gas parts such as the sensitive areas of some sensors may require a special attention as high pressure high temperature (HPHT) environment, corrosion and abrasion may affect their performances in the long term. Additionally, oil and gas sensors may often be exposed, during the same drilling work, to various drilling fluids containing hydrophilic solid particles or heavy molecules such as asphaltenes, resins or heavy alkanes which tend to aggregate on hydrophilic alloy surfaces. Diamond coatings have thus been identified as attractive candidates to protect sensor used during drilling operations. Indeed, diamond materials due to their excellent hardness and wear, low friction coefficient, corrosion resilience and chemical inertness further to high natural resilience to fouling are especially suitable to be used in harsh environments. However, diamond coating on Ni-alloy such as Inconel could not be done by MP-CVD common processes. The current study has proposed solutions, and namely the development of three different processes aiming at a strong and adherent diamond coating on Inconel718. These three processes differ by their roughness and their difficulties of implementation. Their advantages for density-viscosity sensors have been assessed in various drilling fluids, and two specific approaches have been identified as particularly promising to mitigate fouling, namely (i) to create a diamond superhydrophobic surface through micro-structuration to get the antifouling Lotus properties, and (ii) the optimization of an electrochemical treatment aiming at cleaning in situ the diamond surfaces downhole. This study has led to propose reaction mechanisms and demonstrated the role of degraded water on the electrochemical treatment. The thesis has demonstrated the potentialities and identified the limits of those approaches. Efficiency of the electrochemical process applied to drilling fluids and crude oils fouling have been successively demonstrated

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38

Hairaye, Camille. "Fonctionnalisation de surfaces par microstructuration laser." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAD013/document.

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Cette thèse porte sur la fonctionnalisation de surface par microstructuration laser. L’étude expérimentale a consisté à texturer des surfaces d’acier inoxydable avec une source laser impulsionnelle à fibre dopée Yb (1030 nm, 300 fs), dans le but de contrôler leur mouillabilité et de les rendre superhydrophobes. Par une optimisation des conditions d’irradiation, il est possible de conférer à la surface une structuration à double échelle de rugosité. Des structures d’une dizaine de micromètres sont réalisées par ablations successives selon un motif de lignes croisées, sur lesquelles se forment des nanostructures auto-organisées. La simulation du couplage de l’énergie dans la cible a permis de déterminer les paramètres opératoires pour limiter l’accumulation thermique en surface. L’étude fait clairement apparaître le rôle de la texturation dans l’apparition du caractère superhydrophobe de la surface, tout en soulignant l’influence des propriétés physico-chimiques du matériau
This PhD thesis is about surface functionalization by laser microstructuring. The experimental study consists in texturing stainless steel surfaces with a pulsed Yb fibre laser source (1030 nm, 300 fs), in order to control their wettability and confer to them superhydrophobic properties. With an optimization of the irradiating conditions on the target, it is possible to confer to the surface a dual-scale roughness. By successive ablations according to a pattern of crossed lines, microstructures in the range of tens of micrometres are realized, on which self-organized nanostructures are superimposed. Simulation of the energy coupling in the material allows to determine the process parameters to be used, in order to limit the thermal accumulation and avoid the melting of the surface. This study reveals the role of the laser texturing in the apparition of the superhydrophobic character and emphasizes the influence of the physicochemical properties of the material

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39

Qi, Lin. "Bioinspired Smart Surfaces with Switchable Wetting Properties for Droplet Manipulation and Controlled Drug Release." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555584165880048.

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40

Filho, Erivelto dos Santos. "Avaliação da molhabilidade e das texturas de superfícies nanoestruturadas através da ebulição em piscina de nanofluidos." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/18/18147/tde-25022019-220332/.

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O presente trabalho envolve a análise experimental do efeito da deposição de nanopartículas por meio da ebulição em piscina na molhabilidade e na textura da superfície. Inicialmente, este estudo apresenta uma análise da literatura sobre métodos de avaliação do ângulo de contato, preparo de nanofluidos, procedimentos de avaliação da rugosidade e possíveis efeitos que a deposição de nanopartículas tem sobre a textura da superfície. Verificou-se para as superfícies recobertas com nanopartículas ângulos de contato próximos a zero e comportamento dinâmico para gotas de água depositadas sobre elas. Desta forma, optou-se por avaliar a molhabilidade qualitativamente através da análise da velocidade de espalhamento de uma gota depositada sobre a superfície recoberta. Caracterizou-se também a massa de nanopartículas depositadas, a morfologia e a rugosidade das superfícies. Efetuou-se o recobrimento das superfícies por meio da ebulição em piscina de nanofluidos a base de água deionizada contendo nanopartículas de Al2O3 (10, 20-30 e 40-80 nm), Cu (25 nm) e SiO2 (15 e 80 nm) para concentrações volumétricas de 0,001, 0,01, 0,1 e 0,5%, submetidos a tempos de ebulição de 15, 30, 45 e 180 minutos em superfícies de alumínio e aço inoxidável. Como resultado final deste estudo concluiu-se que a rugosidade superficial e a molhabilidade se elevam com a deposição das nanopartículas. Além disso, a molhabilidade aumenta com o incremento da área da superfície recoberta com aglomerados.
The present study concerns an investigation on the wettability and the surface texture behavior of flat aluminum and stainless steel plates covered with porous thin-films of nanoparticles obtained through pool boiling of nanofluids. Since the contact angle of the obtained surfaces is small and in many cases the deposited droplet exhibits a dynamic behavior, dynamic top-down analyses of spreading droplets were performed. Evaluations were performed of nanoparticles mass deposition on the sample, surface roughness and micro-structural with an SEM (Scanning Electron Microscopy). Experiments were performed for nanofluids containing nanoparticles of Al2O3 (10, 20-30 and 40-80 nm), Cu (25nm) and SiO2 (15 and 80 nm) for volumetric concentrations of 0.001, 0.01, 0.1 and 0.5% for pool boiling time set to 15, 30, 45 and 180 minutes over aluminum and stainless steel plates. As a final result of this study it was found that surface roughness and wettability increase with the deposition of the nanoparticles. In addition, the wettability increases with increasing of the surface area covered with clusters.

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41

Batista, Jorge Leonardo Leite. "Modelamento de ângulos de contato em superfícies superhidrofóbicas por minimização de energia." Universidade do Estado de Santa Catarina, 2013. http://tede.udesc.br/handle/handle/1981.

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The control of surface wettability is an issue of great scientific interest because of the large number of applications both as hydrophobic to hydrophilic surfaces, such as medical instruments, fluidic microdevices, coating for microdevices, manipulation of nanoparticles, microscale motors, lubricants, waterproofing surfaces and even instruments for domestic use. The objectives of this work are to compare the values obtained in experiments with surfaces of well-defined topography with available theoretical models and characterize the transition between hydrophobic and superhydrophobic surfaces with the proposition of configurations and criteria that lead to a better understanding of the wettability and superhydrophobic surfaces production, in the light of the energy minimization.
O controle da molhabilidade de superfícies é um tema de grande interesse científico em função da grande quantidade de aplicações, tanto para superfícies hidrofílicas quanto hidrofóbicas, como é o caso de instrumentos médicos, microdispositivos fluídicos, recobrimento para microdispositivos, manipulação de nanopartículas, motores em microescala, lubrificantes, impermeabilização de superfícies e mesmo em instrumentos de uso doméstico. Os objetivos deste trabalho são comparar os valores obtidos em experimentos com superfícies de topografia bem definida com os modelos teóricos disponíveis e caracterizar a transição entre superfícies hidrofóbicas e superhidrofóbicas, com a proposição de configurações e critérios que levem a um melhor entendimento da molhabilidade e da produção de superfícies superhidrofóbicas, sob a luz da minimização de energia.

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42

Vittoz, Christelle. "Étude de l'acido-basicité des surfaces par mouillabilité et XPS : application aux aciers inoxydables." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0042.

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Les aciers inoxydables sont des materiaux caracterises en surface par une couche passive, protectrice vis-a-vis de la corrosion, dont la composition chimique et la structure varie en fonction de la composition de l'alliage et de l'histoire de l'echantillon (nature du recuit, du vieillissement, du traitement de surface). Dans de nombreux domaines d'applications, la connaissance des proprietes d'adhesion de ces surfaces est necessaire. L'objet de cette etude consiste de determiner en particulier les caracteristiques acido-basiques de ces surfaces. Pour cela, nous avons utilise une methode originale basee sur la methode de la goutte posee dont le principe consiste a analyser l'evolution des angles de contact en fonction du ph de la solution aqueuse. A partir des proprietes des oxydes en presence d'une solution aqueuse, on a pu demontrer que cette evolution permet d'obtenir le point de charge nulle (pcn) et la charge maximale de la surface etudiee, ces parametres etant directement relies aux proprietes acido-basiques des surfaces au sens de brnsted. Dans un premier temps, l'application de cette methode pour la caracterisation des proprietes acido-basiques de surfaces modeles (silice, alumine) a permis de valider le principe et l'approche theorique proposee. Ensuite, des surfaces d'aciers inoxydables (aisi 304, fecrsi) ayant subi differents traitements ont ete ainsi caracterisees. Une etroite correlation a ete mis en evidence entre le comportement acido-basique et la composition chimique de la surface determinee par les spectroscopie d'electrons (xps, aes). Au regard de ces premiers resultats, il semble que les proprietes acido-basiques des aciers inoxydables peuvent etre modifier en modifiant la chimie des films passifs.

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43

Mortier, Claudio. "Conception de surfaces bio-inspirées à mouillabilité contrôlée à partir de polymères conducteurs." Thesis, Université Côte d'Azur (ComUE), 2017. http://www.theses.fr/2017AZUR4110/document.

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Le contrôle de la mouillabilité de surface est un enjeu majeur pour le développement de matériaux innovants liés aux nano, bio et smart technologies. La mouillabilité est fonction de deux paramètres majeurs : l’énergie de surface du matériau et sa morphologie. La combinaison de ces deux paramètres est à la base de phénomènes tels que la super/parahydrophobie ou la superoléophobie. Ces capacités extrêmes à repousser les liquides avec soit une forte ou faible adhésion sont des propriétés de surface très intéressantes pour de multiples applications industrielles. La présente thèse propose l’étude d’une série de dérivés du polypyrrole élaborés par électrodéposition permettant d’influencer les paramètres régissant la mouillabilité de surface. Par cette approche, il a été possible d’élaborer des surfaces aux morphologies diverses avec une gamme de mouillabilité complète. Les différentes fonctionnalisations par des groupements hydrophobes greffés sur différentes positions préférentielles du monomère ont conduit à l’élaboration de surfaces para et superhydrophobes mettant en évidence l’impact de l’énergie de surface et de la morphologie sur la mouillabilité. Des études préliminaires ont mis en évidence la possibilité d’obtenir des morphologies variées allant de sphères jusqu’à des fibres à l’échelle du micro/nanomètre. Finalement, ces travaux contribuent à un contrôle en amont de la mouillabilité et de la morphologie de surface pour de nombreuses applications potentielles comme les matériaux collecteurs d’eau, les membranes séparatrices de liquide ou bien les revêtements auto nettoyant
The control of the surface wettability is a key point for the development of innovative materials in several domains such as nano-, bio- and smart-technologies. The wettability is a function of two main parameters of the materials, such as the surface energy and the surface morphology. The combination of these two parameters allows to observe wetting phenomena as super/parahydrophobicity and superoleophobicity. These extreme abilities to repel liquids with different adhesion behaviors are very interesting properties for several industrial applications. This work presents a series of polypyrrole derivatives elaborated by electrodeposition allowing to influence the parameters driving the surface wettability. Following this approach, it was possible to develop surfaces with several types of morphology and different wetting behaviors from a low to high wettability. The different functionalizations using hydrophobic compounds grafted on various preferential positions on the monomer core yielded to para and superhydrophobic surfaces showing the impact of the surface energy and morphology on the wettability. Thanks to preliminary studies, it was showed the possibility to obtain several morphologies from spherical aggregates to fibers at the micro/nano scale. Finally, this work contributes to an upstream control of the surface wettability and morphologies for many potential applications such as water harvesting, separation membranes and self-cleaning coatings

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44

Whiteley, Amelia Jane. "Ingénierie de surfaces antimicrobiennes : combinaison de topographie et de fonctionnalisation par dépôt chimique en phase vapeur par polymérisation amorcée in situ et plasma atmosphérique froid." Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALI043.

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Alors que les biofilms continuent de causer de nombreux dégâts dans diverses industries, entrainant des problèmes de santé, des défaillances de matériel et des coûts non négligeables, les stratégies traditionnelles de lutte contre le biofilm sont remises en question. En effet, la croissance de l’antibiorésistance ainsi que la constatation de la toxicité de certains biocides, mettent en lumière les limites de telles approches. Ainsi, plutôt que de s’attaquer à l’élimination de biofilm, de nouvelles stratégies, qui consistent à éviter l’adsorption bactérienne, sont en train d’être étudiées, notamment avec des surfaces hydrophobes ou hydrophiles. Dans cette thèse, un polymère organosilicié hydrophobe mais sans fluor, a été déposé sous forme de couche mince à l’aide de deux techniques innovantes : le plasma atmosphérique froid à décharge par barrière diélectrique (DBD-CAP) et le dépôt chimique en phase vapeur par une polymérisation amorcée in-situ (iCVD), créant respectivement des polymères plasma et conventionnels. L’iCVD a aussi été utilisé pour fonctionnaliser des surfaces avec le poly(vinyl pyrrolidone) superhydrophile. Ce dernier, malgré des propriétés de mouillabilité intéressantes, ne permet pas une utilisation dans des milieux liquides tels que des suspensions bactériennes, à cause de sa solubilité. Pour palier à cela, le précurseur organosilicié a été utilisé comme agent de réticulation, et les deux monomères ont été co-injectés par iCVD, formant un copolymère hydrophile et insoluble. Ces polymères ont été déposés sur des surfaces planes, mais aussi structurées : avec des microstructures apportées par lithographie par nanoimpression, et une rugosité apportée par gravure plasma. En effet, il a été montré dans la littérature que combiner chimie et topographie peut avoir de nombreux avantages pour lutter contre le biofilm. Pour finir, ces surfaces ont été incubées dans des suspensions bactériennes, afin de regarder leur influence sur l’adhésion des bactéries
As biofilms continue to cause damage in many different industries, leading to health issues, device failure and numerous costs, the traditional strategies used to fight against biofouling are being questioned. Indeed, the rise of antibioresistance and concerns over the toxicity of other biocides bring to light the limits of such approaches. Rather than focusing on eliminating biofilm, bioinspired strategies suggest limiting the initial bacterial adsorption by developing hydrophobic or hydrophilic surfaces. In this thesis, hydrophobic fluorine-free organosilicate thin films were deposited using two innovative deposition methods: Dielectric Barrier Discharge Cold Atmospheric Plasma (DBD-CAP) and initiated Chemical Vapour Deposition (iCVD), respectively leading to plasma polymers and conventional polymers. iCVD was also used to functionalise surfaces with superhydrophilic poly(vinylpyrrolidone). While the latter had interesting wettability properties, it’s solubility made it an impossible coating for devices to be found in bacterial suspensions or other liquid media. To overcome this, the organosilicate precursor was used as a crosslinking agent and both monomers were simultaneously injected into the iCVD reactor, creating hydrophilic and insoluble copolymers. As well as depositing these polymers on planar surfaces, they were used to coat substrates with microscale topography brought by nanoimprint lithography, and roughness achieved by plasma etching. Indeed, it has previously been shown in the literature that there are many advantages in combining chemistry and topography for antibiofouling surfaces. Finally, the developed surfaces were incubated with bacterial suspensions to assess their influence of bacterial adhesion

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45

Belaud, Vanessa. "Structuration de surfaces au moyen d'un traitement laser femtoseconde : applications à la fonctionnalisation de surface du polypropylène en vue de sa métallisation." Thesis, Ecully, Ecole centrale de Lyon, 2014. http://www.theses.fr/2014ECDL0003/document.

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Ce présent travail de thèse porte sur l’étude du potentiel d’un traitement de surface par laser femtoseconde comme étape de substitution aux traitements réalisés actuellement lors de la métallisation de polymère. Pour cela, l’étude des modifications chimiques et morphologiques induites par traitement laser femtoseconde ainsi que leurs influences respectives sur les propriétés d’adhérences et de mouillabilités de la surface polypropylène sont présentées. Une revue bibliographique met en évidence la faisabilité d’une modification contrôlée de la surface du polypropylène après traitement laser femtoseconde. De plus, ces modifications engendrent une évolution démontrée des propriétés de mouillage qui peuvent répondre à certaines demandes industrielles. Après traitement laser femtoseconde, la surface traitée répond de différentes manières à la sollicitation en fonction de ses propriétés intrinsèques. Les expériences d’impacts localisés et de surfaces nous ont conduits à observer trois stades de modifications topographiques pour les conditions étudiées : un phénomène d’incubation, d’accumulation et d’ablation. Ce dernier a fait l’objet d’une étude plus approfondie. De manière générale, on observe deux régimes d’ablation linéaires pour l’ensemble des densités de puissance étudiées lorsque l’on étudie la profondeur d’ablation en fonction du nombre d’impulsion et le volume d’ablation en fonction de la densité de puissance cumulée. Enfin, nous montrons que les liaisons présentes en surface après traitement sont dépendantes de deux facteurs ; la densité de puissance cumulée utilisée et l’environnement de travail. Sachant que les modifications topographiques obtenues sont de types multi-échelles, les résultats ont été analysés sur la base des modèles de Wenzel (1936) et de Cassie-Baxter (1944) relatifs à la théorie du mouillage de surfaces rugueuses. Les résultats expérimentaux et leurs corrélations avec les paramètres de rugosités 3D calculés à différentes échelles ont été traités par une analyse statistique. On observe alors un comportement mixte avec un contact intime de la goutte sur les sommets des aspérités (modèle de Wenzel) et un contact hétérogène (airpolypropylène) à une échelle mésoscopique (état « fakir » décrit par le modèle de Cassie-Baxter). Toutefois, la situation où la goute repose sur le sommet des structures (CB) n’est pas toujours stable. Nous avons étudié la transition de l’état CB à l’état W par des expériences d’évaporation. On observe que cette transition est fortement dépendante de la chimie de surface dont la contribution est prépondérante sur les propriétés d’adhérence métal/PP. En contrôlant cette propriété, il est alors possible de répondre à une problématique industrielle de galvanoplastie (adhérence augmenté par le traitement laser) ou d’électroformage (adhérence faible permettant une réplication de bonne qualité des motifs)
This work presents the potential of a femtosecond laser surface treatment as an alternative step of pretreatments during the metallization of polymer. To do this, the study of chemical and morphological modification induced by femtosecond laser treatment and their respective influences on the properties of adhesion and wettability of polypropylene surface are presented. A literature review highlights the feasibility of a controlled surface modification after femtosecond laser treatment of polypropylene (PP). In addition, it is known that these modifications changes the wetting properties and can be used to meet industrial applications development. After femtosecond laser treatment, the treated surface responds to the solicitation with different morphological comportment according to its intrinsic properties. Experiences of localized impacts and surfaces us to observe three stages of topographic changes to the conditions studied: an incubation phenomenon of accumulation and ablation. The ablation phenomenon is further study. Generally, two linear ablation regime is observed for all power densities examined when considering the depth of ablation as a function of the pulse number and the ablation volume according to the accumulated power density. Finally, we show that the bonds present on the surface after treatment are dependent on two factors: the accumulated power density used and the working environment. Knowing that topographic obtained is multi-scales, the results were analyzed on the basis of models Wenzel (W)(1936) and Cassie–Baxter (CB) (1944) which explain the theory of wetting of rough surfaces. The experimental results and their correlations with 3D roughness parameters calculated at different scales were treated by statistical analysis. We observe a mixed model behavior with intimate contact of the drop on the tops of the asperities (Wenzel model) and a heterogeneous contact (air - PP) in a mesoscopic scale (state " fakir " described by the Cassie -Baxter model). However, this situation where the drop sits on the top of asperities (CB) is not always the most stable. We have studied the transition between the CB state and the W state by evaporation experiments. It is observed that this transition is strongly dependent on the surface chemistry whose contribution is much greater than the adhesion properties metal / PP. If controlling this property, it is possible to obtain two industrial applications: electroplating (increased adhesion by laser treatment) or electroforming (low adherence to replicate the topography)

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46

Marron, François. "Contribution mathématique à l'identification des paramètres adéquats pour la modélisation de la mouillabilité." Vandoeuvre-les-Nancy, INPL, 1997. http://www.theses.fr/1997INPL115N.

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L’objectif de ce travail consiste à identifier des paramètres susceptibles de caractériser les propriétés de mouillabilité d'une paroi à un fluide en présence d'un autre fluide. On s'intéresse, plus particulièrement, à la modélisation de l'équilibre d'une goutte axisymétrique posée sur une paroi horizontale ; cette modélisation conduit à un problème de Cauchy dépendant de trois paramètres inconnus. L’interprétation de l'expérience d'hystérésis fournit une liaison d'ordre phénoménologique entre ces trois paramètres. Différentes approches (analytiques, asymptotiques et numériques) pour la résolution du problème de Cauchy sont effectuées afin d'obtenir d'autres liaisons entre ces trois grandeurs à identifier.

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47

Biguenet, Florence. "Contribution à l'identification de paramètres pour la mouillabilité à partir de modèles énergétiques de milieux continus." Vandoeuvre-les-Nancy, INPL, 1998. http://www.theses.fr/1998INPL082N.

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Nous cherchons les paramètres caractéristiques de la mouillabilité des milieux en présence (fluide1/fluide2/solide) qui sont nécessaires pour la détermination de l'équilibre capillaire (avec ou sans gravite). Nous nous plaçons dans le cadre des fluides doués de capillarité interne et de la théorie du second gradient, pour modéliser l'ensemble des deux fluides loin de la paroi ; nous prolongeons ce modèle pour tenir compte d'une perturbation du comportement au voisinage de cette paroi. Nous proposons de plus, en partant d'une approche moléculaire, une prise en compte de l'action du solide sous forme d'efforts volumiques ou surfaciques. Une application au cas d'une goutte axisymétrique de liquide dans sa vapeur permet, à l'aide de développements asymptotiques raccordés : _ de montrer que le fluide ainsi modélisé rend compte d'un saut de pression vérifiant la loi de Laplace à travers la zone interfaciale _ de mettre en évidence l'importance du choix de la loi d'état en pression _ d'aborder une étude au voisinage de la ligne triple qui semble montrer que le rôle de la courbure moyenne y devient négligeable.

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48

Jacquot, Francis. "Contributions expérimentale et théorique à une nouvelle approche de la mouillabilité." Vandoeuvre-les-Nancy, INPL, 1998. http://www.theses.fr/1998INPL056N.

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L’objectif de ce travail, qui s'inscrit dans le cadre d'une équipe de modélisation mathématique, consiste à caractériser les paramètres susceptibles de définir les propriétés de mouillabilité d'un liquide (environné d'un autre fluide) sur la surface d'un solide. Cette étude, essentiellement expérimentale, s'est concentrée sur le cas d'une goutte sessile posée. Elle s'est attachée à déterminer une relation entre l'aire de base d'une telle goutte et de son volume, lorsque l'on fait évoluer ce dernier dans une situation quasi-statique, engendrant ainsi un hystérésis. Pour cela, nous décrivons dans un premier temps la mise au point d'un banc de mesure sophistiqué. Après avoir testé différentes conjectures et corrélations, nous mettons à jour une loi mixte très prometteuse, et en étudions l'intérêt théorique, permettant l'établissement d'une liaison phénoménologique entre trois paramètres. Enfin, nous abordons une interprétation énergétique de la loi obtenue.

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49

Anand, Kanika. "Surface properties of complex intermetallics at the nanoscale : from fundamentals to applications." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0239/document.

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Les alliages métalliques complexes (CMAs) sont des composés intermétalliques dont la structure cristallographique diffère de celle des alliages conventionnels par le nombre conséquent d'atomes dans la maille (jusqu'à plusieurs milliers d'atomes), généralement arrangés sous forme d'agrégats atomiques de haute symétrie. Ils sont prometteurs pour un certain nombre d'applications technologiques, en particulier les revêtements fonctionnels, en raison de leurs propriétés de surface uniques. Cette thèse a pour objectif, à la fois la détermination de la structure et des propriétés électroniques d’une surface d’un CMA de la famille des clathrates intermétalliques, et des propriétés de mouillage intrinsèques de plusieurs CMAs à base d’aluminium. Dans une première partie, nous nous sommes intéressés aux surfaces de bas indice (100) et (110) du clathrate Ba8Au5.25Ge40.75. Leurs structures atomiques et électroniques ont été déterminées en combinant des expériences de sciences des surfaces et des calculs basés sur la théorie de la fonctionnelle de la densité. La structure tridimensionnelle de Ba8Au5.25Ge40.75, formée d'un réseau de deux types de cages (structure hôte) à base de germanium et d’or, qui emprisonnent les atomes de Ba, induit une nanostructuration de la surface contrôlée par son orientation, puisque le type de cages préservées à la surface diffère pour les surfaces (100) et (110). Dans les deux cas, les atomes de Ba qui protrudent à la surface, ont un rôle primordial pour la stabilité de surface : ils assurent un transfert de charge qui sature les liaisons pendantes des atomes de germanium en surface. Dans une seconde partie, les propriétés intrinsèques de mouillage de plusieurs CMAs à base d’aluminium, ont été déterminées par une approche couplant des mesures de microscopie et des calculs ab initio. Expérimentalement, les angles de contact de gouttes de plomb (métal sonde) sur plusieurs surfaces de CMAs ont été systématiquement mesurés. Les angles précédents étant fonction, entre autres, de l’énergie interfaciale, des calculs d'énergie interfaciale ont été menés, d’une part avec un substrat d’un métal simple, Al(111), et d’autre part sur un substrat de CMA, Al13Co4(100). Les résultats obtenus mettent en évidence une forte influence de la structure de l’interface sur l’énergie interfaciale
Complex metallic alloys (CMAs) are intermetallic compounds possessing a large unit cell containing several tens to hundreds of atoms. Their structure can be described alternatively by the packing of highly symmetric atomic clusters. Clathrate (or cage) compounds are a new class of CMAs having a crystal structure described by a complex arrangement of covalently-bonded cages. The Ba8Au5.25Ge40.75 type-I clathrate is one such cage compound, whose bulk properties have been (and still are) extensively explored for thermoelectric applications. In fact, it is possible to tune the compound electronic structure by a fine control of its bulk composition. Regarding the properties of the Ba8Au5.25Ge40.75 surface, information remains scarce if not inexistent. However, it is known that the surfaces of CMAs often exhibit interesting surface properties. To this end, we have studied two low-index surfaces: BaAuGe(100) and BaAuGe(110) by a combination of experimental (XPS; LEED; STM) and computational (DFT) methods. Experimental results show no evidence for surface segregation and LEED patterns are consistent with (1x1) bulk terminations with no surface reconstruction. The interplay between the 3D nano-caged structure and 2D surfaces is investigated. We demonstrate that the surface structures of the two surfaces considered preserve the bulk structure cages in addition to an ordered arrangement of surface Ba atoms. The two surfaces are formed by a breakage of highly directional covalent bonds present within the framework, hence leading to destabilizing dangling bonds. Ab initio calculations show that the surface structure is stabilized through electron charge transfer from protruding Ba to surface Ge and Au atoms, saturating the dangling bonds. This charge-balance mechanism lifts the possible surface reconstruction envisaged. We reveal how the surface nanostructuration is surface orientation dependent. The results indicate that the surface electronic structure of BaAuGe(110) is impacted by the Au surface concentration. The surface models for BaAuGe(100) and BaAuGe(110) present a metallic character and low work function values, useful for further applications. Such structurally complex surfaces may also be used as templates for novel nanoscale architectures. Further in this work, we also applied the state-of-the-art surface science techniques to investigate the wetting properties of Al-based CMAs. In these experiments, chemically inert Pb element was used as a metal probe. Systematic analysis is done to find the correlation between the wetting properties and the electronic structure properties of these CMAs. Interfacial energy calculations have been performed to model the Pb/CMA interface based on few approaches reported in literature. We have tested these approaches on a moiré patterned Pb(111)/Al(111) interface. This interface is found to be controlled by geometric factors. Hence, an acquired understanding was applied to Pb deposited on Al13Co4(100) (Al-rich side) interface

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50

Anand, Kanika. "Surface properties of complex intermetallics at the nanoscale : from fundamentals to applications." Electronic Thesis or Diss., Université de Lorraine, 2018. http://www.theses.fr/2018LORR0239.

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Abstract:

Les alliages métalliques complexes (CMAs) sont des composés intermétalliques dont la structure cristallographique diffère de celle des alliages conventionnels par le nombre conséquent d'atomes dans la maille (jusqu'à plusieurs milliers d'atomes), généralement arrangés sous forme d'agrégats atomiques de haute symétrie. Ils sont prometteurs pour un certain nombre d'applications technologiques, en particulier les revêtements fonctionnels, en raison de leurs propriétés de surface uniques. Cette thèse a pour objectif, à la fois la détermination de la structure et des propriétés électroniques d’une surface d’un CMA de la famille des clathrates intermétalliques, et des propriétés de mouillage intrinsèques de plusieurs CMAs à base d’aluminium. Dans une première partie, nous nous sommes intéressés aux surfaces de bas indice (100) et (110) du clathrate Ba8Au5.25Ge40.75. Leurs structures atomiques et électroniques ont été déterminées en combinant des expériences de sciences des surfaces et des calculs basés sur la théorie de la fonctionnelle de la densité. La structure tridimensionnelle de Ba8Au5.25Ge40.75, formée d'un réseau de deux types de cages (structure hôte) à base de germanium et d’or, qui emprisonnent les atomes de Ba, induit une nanostructuration de la surface contrôlée par son orientation, puisque le type de cages préservées à la surface diffère pour les surfaces (100) et (110). Dans les deux cas, les atomes de Ba qui protrudent à la surface, ont un rôle primordial pour la stabilité de surface : ils assurent un transfert de charge qui sature les liaisons pendantes des atomes de germanium en surface. Dans une seconde partie, les propriétés intrinsèques de mouillage de plusieurs CMAs à base d’aluminium, ont été déterminées par une approche couplant des mesures de microscopie et des calculs ab initio. Expérimentalement, les angles de contact de gouttes de plomb (métal sonde) sur plusieurs surfaces de CMAs ont été systématiquement mesurés. Les angles précédents étant fonction, entre autres, de l’énergie interfaciale, des calculs d'énergie interfaciale ont été menés, d’une part avec un substrat d’un métal simple, Al(111), et d’autre part sur un substrat de CMA, Al13Co4(100). Les résultats obtenus mettent en évidence une forte influence de la structure de l’interface sur l’énergie interfaciale
Complex metallic alloys (CMAs) are intermetallic compounds possessing a large unit cell containing several tens to hundreds of atoms. Their structure can be described alternatively by the packing of highly symmetric atomic clusters. Clathrate (or cage) compounds are a new class of CMAs having a crystal structure described by a complex arrangement of covalently-bonded cages. The Ba8Au5.25Ge40.75 type-I clathrate is one such cage compound, whose bulk properties have been (and still are) extensively explored for thermoelectric applications. In fact, it is possible to tune the compound electronic structure by a fine control of its bulk composition. Regarding the properties of the Ba8Au5.25Ge40.75 surface, information remains scarce if not inexistent. However, it is known that the surfaces of CMAs often exhibit interesting surface properties. To this end, we have studied two low-index surfaces: BaAuGe(100) and BaAuGe(110) by a combination of experimental (XPS; LEED; STM) and computational (DFT) methods. Experimental results show no evidence for surface segregation and LEED patterns are consistent with (1x1) bulk terminations with no surface reconstruction. The interplay between the 3D nano-caged structure and 2D surfaces is investigated. We demonstrate that the surface structures of the two surfaces considered preserve the bulk structure cages in addition to an ordered arrangement of surface Ba atoms. The two surfaces are formed by a breakage of highly directional covalent bonds present within the framework, hence leading to destabilizing dangling bonds. Ab initio calculations show that the surface structure is stabilized through electron charge transfer from protruding Ba to surface Ge and Au atoms, saturating the dangling bonds. This charge-balance mechanism lifts the possible surface reconstruction envisaged. We reveal how the surface nanostructuration is surface orientation dependent. The results indicate that the surface electronic structure of BaAuGe(110) is impacted by the Au surface concentration. The surface models for BaAuGe(100) and BaAuGe(110) present a metallic character and low work function values, useful for further applications. Such structurally complex surfaces may also be used as templates for novel nanoscale architectures. Further in this work, we also applied the state-of-the-art surface science techniques to investigate the wetting properties of Al-based CMAs. In these experiments, chemically inert Pb element was used as a metal probe. Systematic analysis is done to find the correlation between the wetting properties and the electronic structure properties of these CMAs. Interfacial energy calculations have been performed to model the Pb/CMA interface based on few approaches reported in literature. We have tested these approaches on a moiré patterned Pb(111)/Al(111) interface. This interface is found to be controlled by geometric factors. Hence, an acquired understanding was applied to Pb deposited on Al13Co4(100) (Al-rich side) interface

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