Wetting behavior of fluid/fluid/solid systems, largely influenced by surface properties and interactions between the three phases, plays a big role in nature and in industrial applications Traditionally, wetting studies have focused on liquid/vapor systems, especially the study of a sessile liquid droplet in air. Liquid/vapor systems can only probe the effects of surface properties and interactions between the solid and the wetting liquid. This type of characterization is inadequate for liquid/liquid systems, where surface wettability is additionally influenced by interactions between the two wetting liquids. The present study is the first to examine the effects of nanoscale roughness on wetting behavior in liquid/liquid systems and the modulation of roughness effects by fluid properties and the wetting order. This study examines both equilibrium and dynamic wetting behavior in liquid/liquid systems using well characterized substrates. Rough substrates were fabricated by coating glass substrates with nanometer sized polymer particles. Partial dissolution of the particles and molecular de-deposition of the polymer allowed for tuning of substrate roughness while retaining the original surface chemistry. The effectiveness of this fabrication technique was verified using electron microscopy and electrokinetic analysis. We examined the wetting behavior in three fluid/fluid systems: an air/water system, a decane/water system, and an octanol/water system. The oils were chosen based on their different polarities. Equilibrium wetting behavior was determined using contact angle measurements. Results indicate that for all systems where the primary wetting fluid was a liquid, an increase of the surface roughness resulted in Cassie-Baxter wetting. How hydrophilic a surface appears with regard to a water/fluid interface depended on the polarity of that fluid. The octanol/water system provided the strongest evidence regarding the effect of wetting order: a transition from Wenzel to Cassie-Baxter wetting was only observed when water was the primary wetting liquid. The observed transition was confirmed using a modified Wenzel/Cassie-Baxter model. The kinetics of droplet spreading was measured using high speed optical microscopy. After a droplet was placed on a solid surface, the motion of the contact line was imaged at a rate of 1000 fps. The wetted area was then extracted using custom Matlab® scripts. The spreading kinetics underwent a transition between two regimes: a visco-inertial regime and a slower spreading regime. Results indicated that surface roughness influenced spreading kinetics in both regimes. The overall spreading rate was always slower for rough surfaces than for smoother surfaces. In liquid/liquid systems, the duration of visco-inertial regime was dependent on the surface roughness as well; in general, it was shorter for smooth substrates compared to rough substrates. Increasing the viscosity of the non-aqueous fluid significantly increased the duration of the visco-inertial regime and decreased the overall spreading rate. This study provides insight into the competitive wetting of solid surfaces relevant in many industrial applications such as oil recovery or inkjet printing, and may guide the development of improved wetting models in an area that currently lacks an adequate theoretical description.

This work has explored the capability of a mixed film composed of oligonucleotides and oligomers to improve the selectivity for the detection of fully complementary oligonucleotide targets in comparison to partially complementary targets which have one and three base-pair mismatched sites. The intention was to introduce a “matrix isolation” effect on oligonucleotide probe molecules by surrounding the probes with oligomers, thereby reducing oligonucleotide-to-oligonucleotide and/or oligonucleotide-to-surface interactions. This resulted in a more homogeneous environment for probes, thereby minimizing the dispersity of energetics associated with formation of double-stranded hybrids. The mixed film was constructed by immobilizing pre-synthesized oligonucleotides onto a mixed aminosilane layer and then growing the oligomer portion by surface-initiated atom transfer radical polymerization (ATRP) of 2-hydroxy methacrylate (PHEMA). The performance of the mixed film was compared to films composed of only oligonucleotides in a series of hybridization and melt curve experiments. Surface characterization techniques were used to confirm the growth of the oligomer portion as well as the presence of both oligonucleotides and oligomer components. Polyatomic bismuth cluster ions as sources for time-of-flight secondary ion mass spectrometry experiments could detect both components of the mixed film at a high sensitivity even though the oligomer portion was at least 200-fold in excess. At the various ionic strengths investigated, the mixed films were found to increase the selectivity for fully complementary targets over mismatched targets by increasing the sharpness of melt curves and melting temperature differences (delta Tm) by 2- to 3-fold, and by reducing non-specific adsorption. This resulted in improved resolution between the melt curves of fully and partially complementary targets. A fluorescence lifetime investigation of the Cy3 emission demonstrated that Cy3-labeled oligonucleotide probes experienced a more rigid microenvironment in the mixed films. These experiments demonstrated that a mixed film composed of oligonucleotides and PHEMA can be prepared on silica-based substrates, and that they can improve the selectivity for SNP discrimination compared to conventional oligonucleotide films.

Semiconductive metal oxides are of great importance in environmental remediation and electronics because of their ability to generate charge carriers when excited with appropriate energy. The electronic structure, light absorption and charge transport properties have made the transition metal oxides an attractive material as photocatalyst. Recently, facet-engineering by morphology control has been intensively studied as an efficient approach to further enhance their photocatalytic performance. However, various processing steps and post-treatments used in the preparation of facet-engineered particles may generate different surface active sites which may affect their photocatalysis. Moreover, many traditional techniques (PL, EPR and XPS) used for materials characterization (oxygen vacancy, hydroxyl group, cation, etc.) are not truly surface specific but analyzing a range from surface few layers to bulk. Accordingly, they can only provide very limited information on chemical states of the surface active features and their distribution among facets, causing difficulties to unambiguously correlate facet-dependent results with activity. As a result, this often leads to different interpretations amongst researchers during the past decades. As the publications of titanium and zinc ranked top two among studies of first row of transition oxides in the past decades, this thesis will firstly review on the disagreements generated among researchers when they correlated the performance of ZnO and TiO₂ with their facet activities based on traditional techniques. As there are shortcomings of these techniques in producing truly facet-dependent features, some results can be misleading and with no cross-literature comparison. To address these issues, we have developed a new technique "probe-molecule-assisted NMR" which allows a genuine differentiation of surface active sites from various facets. This surface-fingerprint technique has been demonstrated to provide both qualitative (chemical shift) and quantitative (peak intensity) information on the concentration and distribution of truly surface features among facets. In light of the new technique, this thesis will revisit the facet-dependent photocatalytic properties and shed light on these issues.

Ce travail de thèse s’inscrit dans lecadre du projet « MOMEQA » dont l’objectif est le soutien à l’innovation dans l’industrie horlogère en Franche-Comté. La première impression visuelle conditionne notre relation à l’objet, c’est pourquoi une finition soignée est primordiale. L’électropolissage est un procédéde dissolution électrochimique permettant der éduire la rugosité de surface d’un objet. La pièce traitée constitue l’anode dans une cellule d’électrolyse. La première partie de l’étude est consacrée aux laitons et à l’acier inoxydable 316 L. Une étude électrochimique préliminaire a permis de définir les conditions optimales d’électropolissage pour chaque matériau et milieu. La suite de l’étude a été dédiée à l’étude des comportements des aciers inoxydables 316L de fonderie comme de fabrication additive, afin de mettre en évidence l’influence du procédé de fabrication sur l’aptitude à l’électropolissage. Un dispositif spécialement conçu a également permis de faire varier les conditions hydrodynamiques et d’appliquer des ultrasons,en vue d’optimiser l’agitation. L’obtention d’une finition poli miroir sur des carrures de montres a validé la conception du pilote. Enfin, l’usage d’un électrolyte moins nocif que les mélanges d’acides, le Deep Eutectic Solvent constitué d’un mélange de chlorure de choline et d’éthylène glycol se montre prometteur. L’utilisation de ces olvant non-conventionnel permet d’utiliser des techniques d’analyses de surface impraticables in-situ en milieu très corrosif, tel que l’AFM. Finalement, un modèle décrivant les mécanismes d’électropolissage de l’acier inoxydable 316 L dans les deux milieux a été proposé, qui permet une bonne simulation des résultats de spectroscopie d’impédance électrochimique / This work is part of the project"MOMEQA" whose main purpose is to supportinnovation in watchmaking industry in Franche-Comté. For high-end pieces, the first visualimpression is crucial and that is why a neatfinishing is required. This is achieved byelectropolishing, which consists in anelectrochemical dissolution process that enablessurface roughness reduction. Although it ispresent in several applications, fundamentalmechanisms of electrochemical polishingremain poorly understood and tailoring theprocess to additive manufacturing parts is in itsearly stages. The first part of the study isdedicated to brass and 316L stainless steel.Basic electrolytic baths (H3PO4 for brasses anda H3PO4/ H2SO4 mixture for 316L stainlesssteel) are used as references. A preliminaryelectrochemical study allows the determinationof optimal electropolishing conditions for eachmaterial and medium. A special attention hasbeen paid to characterization methods, such asmicro-roughness, brightness, microstructure,texture and corrosion resistance. Subsequently,the study was restricted to both cast and additivemanufacturing 316L stainless steels, in order toidentify the influence of manufacturing processon the electropolishing ability. To meet theproject requirements, a pilot cell dedicated tolarge area parts was designed and built. The aimwas to study the scale-up as well as the effectsof workpieces shape. The outcome of this studywas the realization of a mirror finish on a watchdial, allowing validation of the pilot-cell design.The last part of our study consists in replicatingthe process in a less harmful electrolyte, a greensolvent (Deep Eutectic Solvent), made by amixture of choline chloride and ethylene glycol.This allows successful electropolishing,compatible with an industrial application.Moreover, it makes possible in-situ AFMmeasurements, impossible in highly corrosiveelectrolytes. Finally, a model forelectropolishing mechanism in the case of 316Lstainless steel was proposed for both media,allowing a good simulation of electrochemicalimpedance spectroscopy behaviour.

INTRODUÇÃO: Superfícies de titânio modificadas por diferentes métodos foram estudadas com base nos parâmetros físicos e químicos de caracterização superficial e sua influência no comportamento de células pré-osteoblásticas (MC3T3) in vitro. MÉTODOS: Discos de titânio comercialmente puro grau II foram submetidos a três métodos de modificação de superfície (polimento, nitretados em plasma em configuração planar e gaiola catódica). As diferentes superfícies foram caracterizadas para observar o efeito do processamento na estrutura da camada superficial, na rugosidade e molhabilidade. Ensaios de adesão e proliferação celular usando linhagens de células pré-osteoblásticas MC3T3 foram realizados para avaliar o efeito das novas superfícies no comportamento celular in vitro. RESULTADOS: Os resultados demonstraram que a nitretação em plasma na configuração de gaiola catódica produz superfícies mais rugosas (p<0,02) e com menores ângulos de contato com a água. CONCLUSÕES: A adesão celular é maior nas superfícies mais rugosas do que nas superfícies polidas (p<0,05) e reagem de modo diferente a composição química do substrato e à topografia da superfície. / PURPOSE: The aim of this study was to evaluated the physico-chemical properties of different titanium surfaces modified by means of low temperature plasma nitridind on rat osteoblast cell adhesion and proliferation. METHODS: Pure Titanium discs grade II was submitted to three different surface preparations (polishing, glow discharge plasma nitriding in planar and cathodic cage configurations). Surface parameters as roughness, wettability and chemichal composition was determined to compare influency of gas mixture on the modified surface material properties. Cellular morphology was observed by scanning electron microscopy. To evaluate the effect of the surface on cellular response, osteoblast cells (MC3T3) adhesion and proliferation was quantified and data analised by Kruskal-Wallis and Friedman statistical tests. RESULTS: plasma nitriding discs shows rougher surfaces( p<0,02) in cathodic cage configuration and lower contact angle values. MC3T3 cells attached on rough surfaces produced by cathodic cage configuration was statistically significant p<0,05 compared to polished discs. CONCLUSIONS: Glow discharge plasma nitriding improve titanium surface roughness and wettability. MC3T3 cell adhesion behavior is related to substrate chemical composition and topography.

Tablets are the most common forms of drug administration. They are convenient to administer and easy to manufacture. However, problems associated with the adhesion of the powders to the tableting tools are common. This phenomenon is known as sticking and even though it has been well documented and studied, it remains poorly understood. The many factors that contribute to good performance of the powders make the sticking problem difficult to solve. The goal of this study is to establish a relationship between the properties measured at the nanoscale to the overall tablet mechanical properties, tablet performance and powder pre-processing induced modifications. By using atomic force microscopy (AFM) we aim to develop an analytical method to characterize the mechanical and adhesive properties of the pharmaceutical powders at the nanoscale. Other methodologies such as scanning electron microscopy (SEM), thermal analyses (DSC, TGA) and tablet strength test were also used. The materials used in this study are commonly used excipients, a sticky drug and magnesium stearate (MgSt). Two different approaches offered by AFM were employed: sharp tip imaging and colloidal probe force measurements. Nano-mechanical properties of the materials were evaluated with a sharp tip cantilever showing that higher adhesion correlates with higher tablet cohesion and that both are significantly affected by the presence of MgSt. AFM characterization of the particle surface mechanical properties at the nanoscale was also used to detect the crystallinity and amorphicity levels of the materials. New approaches to presenting such data considering the particle heterogeneity and to track the dynamics of surface recrystallization are revealed. Adhesive interactions between a steel sphere and sticky and non-sticky powders were performed with the colloidal probe technique. Sticky materials presented a higher adhesion against the steel surface, and reveal the mechanism of stickiness. This work thus contributes to the provision of predictability of the performance of formulations at an early stage of the development process. / <p>QC 20170315</p>

Title: Plasma treatment of porous structures Author: Mykhailo Vaidulych Department / Institute: Department of Macromolecular Physics Supervisor of the doctoral thesis: Prof. Assist. Jan Hanuš, Ph.D., Department of Macromolecular Physics Abstract: The thesis is focused on the implementation of low-temperature plasma for the modification of porous materials. Two main strategies are involved: functionalization through the deposition of functional nanocomposite coatings and low-pressure plasma etching. In the first case, a gas-phase step-by-step deposition process based on the combination of deposition of nanoparticles and thin films was developed to obtain super-wettable nanocomposite coatings on filtration membranes. It was shown that the deposition parameters of thin films and particles of plasma polymer can tune the wetting characteristic of the membranes whereas embedding copper nanoparticles endows them with antibacterial properties. As a result, highly efficient superhydrophobic/superoleophilic and smart superamphiphilic membranes were successfully fabricated for oil/water separation. Plasma processing in the atmosphere of argon, oxygen or nitrogen was utilized to modify hard metal/polymer nanocomposites (Ag/a-C:H) with potential to be used as functional coatings for bone implants. An anisotropic etching...

Knowledge on metal release processes from stainless steel powder, which can be potentially inhaled at occupational settings, is essential within the framework of human health and environmental risk assessments. An in-depth knowledge concerning powder history, physical properties of particles (e.g. size, morphology, and active surface area) combined with their chemical properties (such as the chemical composition of the particles and their metal release behavior) is needed for better understanding of the interaction mechanisms between metal powders and humans. So far, limited in vitro and in vivo studies exist that assess the correlation between stainless steel surface properties, protein adsorption effects, and metal release processes. The aim of this study is to add information to fill this knowledge gap through in vitro investigations of protein-induced metal release (iron, nickel, chromium, and manganese) and induced surface changes of five differently sized and/or produced (water-atomized (WA) and gas-atomized (GA)) stainless steel powder particles (three austenitic: AISI 316L, 310B, and 304B; one martensitic: AISI 410L; and one ferritic: AISI 430L) after exposure up to one week into a phosphate buffer saline (PBS) solution of pH 7.2-7.4 containing either lysozyme (LYS) or bovine serum albumin (BSA). The results show that the outmost surface oxide composition of the powders strongly depends on the production method and particle size. Gas-atomized 316L powder particles (with spherical shapes) indicated a high relative manganese content in their surface oxide (more significant in the case of 316L particles sized &lt;4µm), while no manganese compounds were detectable in the surface oxide of water-atomized powders (of irregular particle shapes). Although austenitic stainless steels should present non-magnetic properties, the investigation of magnetic properties indicated that differently sized gas-atomized 316L particles and water-atomized 304B were to some extent ferromagnetic suggesting the presence of ferrite. BSA induced a significant enrichment of chromium in the surface oxide of all investigated powders (especially for ferritic WA430L and austenitic WA316L), except in the case of 316L powders (&lt;4µm) showing no significant change. Metal release studies illustrated that both proteins enhanced the amount of released metal, with a preferential iron release from water-atomized particles and manganese release from gas-atomized powders. BSA-containing medium induced the highest extent of metal release in comparison with other tested biological media (up to 35-fold increase in the case of ferritic 430L particles produced by water atomization). Comparison between the metal release behavior of particulate and massive stainless steel indicated a significantly higher extent of metal released from abraded stainless steel sheets compared with particles, which is most probably an effect of freshly abraded surfaces of the massive metal sheets, not true for the particles with aged surface oxides, along with the presence of higher relative chromium content in the surface oxide.

Knowledge on metal release processes from stainless steel powder, which can be potentially inhaled at occupational settings, is essential within the framework of human health and environmental risk assessments. An in-depth knowledge concerning powder history, physical properties of particles (e.g. size, morphology, and active surface area) combined with their chemical properties (such as the chemical composition of the particles and their metal release behavior) is needed for better understanding of the interaction mechanisms between metal powders and humans. So far, limited in vitro and in vivo studies exist that assess the correlation between stainless steel surface properties, protein adsorption effects, and metal release processes. The aim of this study is to add information to fill this knowledge gap through in vitro investigations of protein-induced metal release (iron, nickel, chromium, and manganese) and induced surface changes of five differently sized and/or produced (water-atomized (WA) and gas-atomized (GA)) stainless steel powder particles (three austenitic: AISI 316L, 310B, and 304B; one martensitic: AISI 410L; and one ferritic: AISI 430L) after exposure up to one week into a phosphate buffer saline (PBS) solution of pH 7.2-7.4 containing either lysozyme (LYS) or bovine serum albumin (BSA). The results show that the outmost surface oxide composition of the powders strongly depends on the production method and particle size. Gas-atomized 316L powder particles (with spherical shapes) indicated a high relative manganese content in their surface oxide (more significant in the case of 316L particles sized &lt;4µm), while no manganese compounds were detectable in the surface oxide of water-atomized powders (of irregular particle shapes). Although austenitic stainless steels should present non-magnetic properties, the investigation of magnetic properties indicated that differently sized gas-atomized 316L particles and water-atomized 304B were to some extent ferromagnetic suggesting the presence of ferrite. BSA induced a significant enrichment of chromium in the surface oxide of all investigated powders (especially for ferritic WA430L and austenitic WA316L), except in the case of 316L powders (&lt;4µm) showing no significant change. Metal release studies illustrated that both proteins enhanced the amount of released metal, with a preferential iron release from water-atomized particles and manganese release from gas-atomized powders. BSA-containing medium induced the highest extent of metal release in comparison with other tested biological media (up to 35-fold increase in the case of ferritic 430L particles produced by water atomization). Comparison between the metal release behavior of particulate and massive stainless steel indicated a significantly higher extent of metal released from abraded stainless steel sheets compared with particles, which is most probably an effect of freshly abraded surfaces of the massive metal sheets, not true for the particles with aged surface oxides, along with the presence of higher relative chromium content in the surface oxide.

This dissertation focuses on copper release in drinking water. Qualitative and quantitative assessment of Cu and Fe corrosion by process water quality was assessed over one year in a field study using finished waters produced from seven different treatment process and eighteen pilot distribution systems (PDSs) that were made from unlined cast iron and galvanized steel pipes, and lined cement and PVC pipes taken from actual distribution systems. Totally seven different waters were studied, which consisted of three source waters: groundwater, surface, and simulated brackish water designated as G1, S1, and RO. With certain pre-established blending ratios, these three waters were blended to form another three waters designated as G2, G3, and G4. Enhanced surface water treatment was CFS, ozonation and GAC filtration, which was designated as S1. The CFS surface water was nanofiltered, which is S2. All seven finished waters were stabilized and chloraminated before entering the PDSs. Corrosion potential was compared qualitatively and quantitatively for all seven waters by monitoring copper and iron release from the PDSs. This dissertation consists of four major parts. (1) Copper corrosion surface characterization in which the solid corrosion products formed in certain period of exposure to drinking water were tried to be identified with kinds of surface techniques. Surface characterization indicated that major corrosion products consists of cuprite (Cu2O) as major underneath corrosion layer and tenorite (CuO), cupric hydroxide (Cu(OH)2) on the top surface. In terms of dissolution/precipitation mechanism controlling the copper concentration in bulk solution, cupric hydroxide thermodynamic model was developed. (2) Theoretical thermodynamic models were developed to predict the copper release level quantitatively based on controlling solid phases identified in part (1). These models are compared to actual data and relative assessment is made of controlling solid phases. (3) Non-linear and linear regression models were developed that accommodated the release to total copper for varying water quality. These models were verified using independent data and provide proactive means of assessing and controlling copper release in a varying water quality environment. (4) Simulation of total copper release was conducted using all possible combinations of water quality produced by blending finished waters from ground, surface and saline sources, which involves the comparison of copper corrosion potentials among reverse osmosis, nanofiltration, enhanced coagulation, lime softening, and conventional drinking water treatment.