Die Benetzbarkeit und Nichtbenetzbarkeit von Oberflächen durch eine Flüssigkeit sind faszinierende und wichtige Phänomene in Wissenschaft und Technologie. Jüngst wurde entdeckt, dass Partikel die Benetzung einer Wasseroberfläche durch ein Öl unterstützen können. Es wurde eine Theorie entwickelt, das Prinzip der zu beschreiben. In der vorliegenden Doktorarbeit wurde diese Theorie im Experiment sowohl qualitativ als auch quantitativ untersucht, wobei zwei Arten von Kieselgelpartikeln Verwendung fanden. Mit Hilfe einer Reihe unregelmäßig geformter Partikel mit variierender Hydrophobie wurde der Einfluss der Oberflächenhydrophobie der Partikel auf die partikel-assistierte Benetzung untersucht. Es wurde herausgefunden, dass die Partikel mit höchster Hydrophilie Linsen aus reinem Öl bilden, während die Partikel in die Wasserphase abtauchen. Die Partikel mit größter Hydrophobie hingegen bewirken die Ausbildung von kleinen Bereichen, in denen Öl und Partikel eine stabile homogene Schicht formen. Für Partikel mit mittlerer Hydrophobie wurden beide Phänomene beobachtet. Diese drei verschiedenen Beobachtungen bestätigen, dass die Oberflächenhydrophobie der Partikel das Benetzungsverhalten des Öls auf der Wasseroberfläche bestimmen. Für die unregelmäßig geformten Partikel war aufgrund des unbekannten Kontaktwinkels ein direkter Vergleich zur Theorie nicht möglich. Um die Theorie quantitativ zu prüfen, wurden sphärische Partikel synthetisiert und ihre Oberflächen mit Hilfe von zehn Silanisierungsmittel modifiziert. Anschließend wurde ein Vergleich der experimentellen Ergebnisse mit dem entsprechenden theoretischen Phasendiagramm durchgeführt. Die Untersuchungen zeigten, dass die theoretischen Vorhersagen zum Großteil mit den experimentellen Ergebnissen übereinstimmen. Es wurden alle Fälle der Benetzung beobachtet, die auch in der theoretischen Beschreibung berücksichtigt wurden. Darüber hinaus wurden auch Abweichungen von der Theorie festgestellt. Haben die Partikel ähnliche Affinitäten zur Luft/Öl- und Öl/Wasser-Grenzfläche, hängt die Beschaffenheit der Benetzungsfilme zusätzlich vom Oberflächendruck ab. Deshalb könnte es notwendig sein, die einfache Theorie zu erweitern um den beschriebenen Beobachtungen Rechnung zu tragen. / Wetting and de-wetting of surfaces by a liquid are fascinating and important phenomena in science and technology. Recently, it was discovered that particles can assist the wetting of a water surface by an oil, and a theory describing the principle behind particle assisted wetting was developed. In this thesis, the theory was experimentally investigated qualitatively and quantitatively by using two series of silica particles. The influence of the surface hydrophobicity of the particles on particle assisted wetting was investigated by a series of irregular shaped particles with varying hydrophobicity. By applying mixtures of particles and oil to a water surface, it was found that for the most hydrophilic particles, only lenses of pure oil formed, with the particles being submerged into the aqueous phase. The most hydrophobic particles helped to form patches of stable homogenous mixed layers composed of oil and particles. For particles with intermediate hydrophobicity, lenses and patches of mixed layers were observed. These three different observations verified that the hydrophobicity of the particle surface determines the wetting behaviour of the oil at the water surface. For the irregular shaped particles with unknown contact angles with liquid interfaces, no direct comparison to the theory was possible. To test the theory quantitatively, a series of spherical particles was synthesized and their surfaces were modified by ten kinds of silane coupling agents; then the experimental results were compared with the corresponding theoretical phase diagram. It indicated that the theory agrees at large with the experimental results. All scenarios of wetting layers taken into account in the theoretical description were observed. In the fine print, deviations from the theory were also observed. If the particles have similar affinities to air/oil and oil/water interfaces, the experimentally observed morphology of the wetting layers depends in addition on the surface pressure. It might therefore be necessary to extend the simple theoretical picture to take these observations into accounts.

The fundamental forces of adhesion are responsible for the spreading of fluids such as crude oil/brine on the reservoir rock surface. These physico-chemical interactions determine the surface energetics of a reservoir and thus their wetting phenomena. Inverse Gas Chromatography is introduced to characterize the surface energy of carbonates (calcite and dolomite) and sandstones (Ottawa sand and Berea sandstone). The behavior of the polar and non-polar interaction forces was investigated at varying water coverage and at different temperatures. The results indicated that in general as the water coverage increased, the Lifshitz-van der Waals component of surface energy decreased to nearly that of the bulk water, while the acid-base component also showed a decreasing trend. The Lifshitz-van der Waals component of surface energy always decreased with increase in temperature, while the acid-base properties mostly increased with temperature with the exception of calcite. / text

Block copolymers demonstrate potential in next-generation lithography as a solution for overcoming the limitations of conventional lithographic techniques. Ideal block copolymer materials for this application can be synthesized on a commercial scale, have high [chi]-parameters promoting self-assembly into sub-20 nm pitch domains, have controllable alignment and orientation, and have high etch contrast between the domains for facilitating pattern transfer into the underlying substrate. Block copolymers that contain silicon in one domain are attractive for nanopatterning since they often fulfill at least three of these requirements. However, silicon-containing materials are notoriously difficult to orient in thin films due to the low surface energy of the silicon-containing block, which typically wets the free surface interface. In this work, the methodology behind material choice and the synthesis of new silicon-containing block copolymers by a variety of polymerization techniques will be described. Thin film self-assembly of the block copolymers with domains oriented perpendicular to the plane of the substrate is achieved using different solvent annealing and neutral surface treatments with thermal annealing conditions. Block copolymer patterns are transferred to the underlying substrate by reactive ion etching and directed self-assembly of the polymers is demonstrated using chemical contrast patterns. Interesting thermodynamics governing the self-assembly of block copolymers with solvent annealing will also be discussed. Finally, new amphiphilic block copolymers will be described that were created with lithographic applications in mind but that are most useful for biological applications in drug delivery. / text

Hydrates in some crude oils have a smaller tendency to form plugs than in others, and lately this is becoming a focus of research. To study this and the action of hydrate antiagglomerants in general, hydrate surface properties must be known. To help in characterizing the surface properties by simulation, the capillary waves of clathrate hydrate surfaces in vacuum are examined in all unique crystal faces by Molecular Dynamics, and an attempt is made to estimate the surface energies in the respective crystal faces from the wave fluctuations [1]. We also attempt to estimate solid/liquid surface energies of hydrate/oil and hydrate/water for a specific face, for comparison. The forcefield OPLS_AA is used for the organic compounds, while TIP4P/ice is used for the water framework. The anisotropy of the surface energy is then estimated and the result compared to the initial growth rate of different crystal faces as found in experiment [2].

Darbe ištirtas elektrofotografinių atspaudų laminavimo stipris bei pailgėjimas atplėšiant laminatą. Tyrimui naudota dešimt skirtingų popieriaus rūšių, šešios laminavimo plėvelių rūšys. Laminavimo stipris testuotas esant dažų dengimo plotui nuo 0 iki 400 % (25 variantai). Nustatyta, kad elektrofotografinių atspaudų laminavimo stipris yra mažesnis už švaraus popieriaus ir tolygiai mažėja didėjant dažų plotui. Laminavimo stipris taip pat priklauso nuo popieriaus ir plėvelės rūšies. Laminavimo blizgiosiomis plėvelėmis laminavimo stipris yra didesnis lyginant su matinėmis plėvelėmis. Šie dėsningumai aiškinami dažų kogezijos ir dažų ir plėvelių adhezijos ypatumais. Nustatytos optimalios laminavimo stiprio atžvilgiu popieriaus ir plėvelių kombinacijos. Darbą sudaro 8 dalys: įvadas, literatūros apžvalga, tyrimų metodika, rezultatai ir jų aptarimas, išvados ir rekomendacijos, santrumpos, literatūros sąrašas, priedai. Darbo apimtis – 59 p. teksto be priedų, 21 lentelė, 35 paveikslai, 17 bibliografinių šaltinių. Darbo priedai pridedami darbo pabaigoje. / The strength and elongation before total delaminating of elctrophotographic prints were investigated. 10 different paper grades and 6 different lamination films were tested. Lamination strength was tested at ink coatings from 0 to 400 % (25 different versions). It was established that lamination strength of electro photographic prints is lower as compared with nonprinted paper. The lamination strength gradually decreases with toner coating and depends on paper and laminating film properties. Glossy films exhibit higher lamination strength as compared with mat tone. These phenomena are explained by toner and films adhesion and cohesion peculiarities. The optimal combinations of paper and lamination film. Thesis consist of: 59 p. text without appendixes, 21 tables, 35 pictures, 17 bibliographical entries. Appendixes are added after the main part of master thesis.

The vast majority of pharmaceutical drug products are developed, manufactured, and delivered in the solid-state where the active pharmaceutical ingredient (API) is crystalline. With the potential to exist as polymorphs, salts, hydrates, solvates, and cocrystals, each with their own unique associated physicochemical properties, crystals and their forms directly influence bioavailability and manufacturability of the final drug product. Understanding and controlling the crystalline form of the API throughout the drug development process is absolutely critical. Interfacial properties, such as surface energy, define the interactions between two materials in contact. For crystal growth, surface energy between crystal surfaces and liquid environments not only determines the growth kinetics and morphology, but also plays a substantial role in controlling the development of the internal structure. Surface energy also influences the macroscopic particle interactions and mechanical behaviors that govern particle flow, blending, compression, and compaction. While conventional methods for surface energy measurements, such as contact angle and inverse gas chromatography, are increasingly employed, their limitations have necessitated the exploration of alternative tools. For that reason, the first goal of this research was to serve as an analytical method development report for atomic force microscopy and determine its viability as an alternative approach to standard methods of analysis. The second goal of this research was to assess whether the physical and the mathematical models developed on the reference surfaces such as mica or graphite could be extended to organic crystal surfaces. This dissertation, while dependent upon the requisite number of mathematical assumptions, tightly controlled experiments, and environmental conditions, will nonetheless help to bridge the division between lab-bench theory and successful industrial implementation. In current practice, much of pharmaceutical formulation development relies on trial and error and/or duplication of historical methods. With a firm fundamental understanding of surface energetics, pharmaceutical scientists will be armed with the knowledge required to more effectively estimate, predict, and control the physical behaviors of their final drug products.

Development of new scientific disciplines such as bioengineering and micro-nano engineering adopting nonconventional materials requests innovative methodologies that can accurately measure the mechanical properties of soft biological materials and characterize surface energy and adhesion properties of them, independent of measurement conditions. One of emerging methods to measure the deformation of materials under stress is digital image correlation (DIC) technique. As a noncontact strain measurement method, DIC has the advantages of prevention of experimental errors caused by the use of contact type sensors and of flexibility in its application to soft materials that are hard to be tested by conventional method. In the first part of the thesis, 2 dimensional and 3 dimensional DIC codes were developed and optimized, and then applied to two critical applications: 1) determining the stress-strain behaviour of polydimethylsiloxane (PDMS) sample, as a model soft material, using the optical images across large deformation region, and 2) detecting the stiffness variation within the gel mimicking the breast tumour using ultrasound images. The results of this study showed the capability of DIC as a strain sensor and suggested its potential as a diagnosing tool for the malignant lesion causing local stiffness variation. In the characterization of surface energy and adhesion properties of materials, two most common methods are contact angle measurement and JKR-type indentation test. In the second part of the thesis, the experimental set-up for these methods were developed and verified by using the PDMS in static (quasi equilibrium) state. From the dynamic tests, it showed its possible usage in studying adhesion hysteresis with respect to speed. The adhesion hysteresis was observed at high speed condition in both contact angle measurement and JKR-type indentation tests.

Biomaterial surface properties such as microtopography and energy can change cellular responses at the cell-implant interface. Phospholipase D (PLD) is required for differentiation of osteoblast-like MG63 cells on machined and grit-blasted titanium surfaces. Here, we determined if PLD is also required on microstructured/high-energy substrates and the mechanism involved. shRNAs for human PLD1 and PLD2 were used to silence MG63 cells. Wild-type and PLD1 or PLD1/2 silenced cells were cultured on smooth-pretreatment surfaces (PT); grit-blasted, acid-etched surfaces (SLA); and SLA surfaces modified to have higher surface energy (modSLA). PLD was inhibited with ethanol or activated with 24,25-dihydroxyvitamin-D₃ [24R,25(OH)₂D₃]. As surface roughness/energy increased, PLD mRNA and activity increased, cell number decreased, osteocalcin and osteoprotegerin increased, and protein kinase C (PKC) and alkaline phosphatase specific activities increased. Ethanol inhibited PLD and reduced surface effects on these parameters. There was no effect on these parameters after knockdown of PLD1, but PLD1/2 double knockdown had effects comparable to PLD inhibition. 24R,25(OH)₂D₃increased PLD activity and production of osteocalcin and osteoprotegerin, but decreased cell number on the rough/high-energy surfaces. These results confirm that surface roughness/energy-induced PLD activity is required for osteoblast differentiation and that PLD2 is the main isoform involved in this pathway. Here we showed that PLD is activated by 24R,25(OH)₂D₃ in a surface-dependent manner and inhibition of PLD reduced the effects of surface microstructure/energy on PKC, suggesting that PLD mediates the stimulatory effect of microstructured/high-energy surfaces via PKC-dependent signaling.

Thesis (M. Phil.)--University of Hong Kong, 1992.

Submitted by Maria Suzana Diniz (msuzanad@hotmail.com) on 2015-11-11T14:30:33Z No. of bitstreams: 1 arquivototal.pdf: 2608900 bytes, checksum: d84a249de88f0e30dd397c603471f675 (MD5) / Made available in DSpace on 2015-11-11T14:30:33Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2608900 bytes, checksum: d84a249de88f0e30dd397c603471f675 (MD5) Previous issue date: 2015-04-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Quasicrystals are materials with unique properties such as high hardness, low surface energy, low coefficient of friction, etc. Due to its high hardness and consequent fragility, the use of quasicrystals becomes limited to coatings and composite materials. This paper is a study of hardness and surface properties of the composite formed by the epoxy matrix and the quasicrystalline reinforcement. The quasicrystalline alloy Al59,2Cu25,5Fe12,3B3 were obtained by melting and made into powder by hand. Then it was ground by high energy milling to reduce the particle size. After milling the powder, it was added in the polymer matrix in volumetric ratios of 1, 10, 20 and 30% where the comparison of the properties was made between the composite of QC on the composite and the pure epoxy resin. For the characterization of quasicristalino powder, we used the X-Ray Diffraction (XRD), Sieve Analysis and Scanning Electron Microscopy (SEM), while for the composite we used the Thermogravimetric Analysis techniques, Shore D hardness test Analysis of the Angle of Contact and SEM. By measuring the contact angle was possible the realization of surface energy calculations and work of adhesion between the constituents. Through this study it is concluded that it was possible to obtain a composite QC / Epoxy with greater hardness and still maintain its surface characteristics. / Os quasicristais são materiais com propriedades únicas, tais como, alta dureza, baixa energia superficial, baixo coeficiente de atrito, etc. Devido a sua alta dureza e consequente fragilidade, o uso dos quasicristais torna-se limitado a revestimentos e em materiais compósitos. Este trabalho consiste no estudo de dureza e de propriedades superficiais do compósito formado pela matriz epoxídica e o reforço quasicristalino. A liga quasicristalina Al59,2Cu25,5Fe12,3B3 foi obtida via fusão e transformada em pó manualmente. Em seguida a mesma foi moída através de moagem de alta energia de modo a diminuir o tamanho de partícula. Após a moagem o pó de QC foi adicionado na matriz polimérica em proporções volumétricas de 1, 10, 20 e 30% onde a comparação das propriedades foi realizada entre os compósitos e a resina epóxi pura. Para a caracterização do pó quasicristalino, utilizou-se as técnicas de Difração de Raio-X (DRX), Análise Granulométrica e Microscopia Eletrônica de Varredura(MEV), já para o compósito foram utilizadas as técnicas de Análise Termogravimétrica, Ensaio de Dureza Shore D, Análise de Ângulo de Contato e MEV. Através da medida do ângulo de contato foi possível a realização dos cálculos de energia de superfície e trabalho de adesão entre os constituintes. Através deste trabalho conclui-se que foi possível a obtenção do compósito QC/Epóxi com maior dureza e ainda assim, mantendo suas características superficiais.