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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Novel Fluorous Hybrid Surface Modification Characterized by Wetting Dynamics, Morphology and Nanomechanics

Nair, Sithara 01 January 2012 (has links)
The surface response of a polymer substrate to external stimuli such as initial wetting is controlled by the outermost molecular layer. Thus, changes on the nanoscale may be engaged to control macroscale wetting behavior. Our work has predominantly focused on surface modification of conventional polyurethane coatings (HMDI-BD-PTMO). Studies on network constrained phase separation and facile polydimethylsiloxane surface functionalization led to the discovery of a simpler one-step and more general approach to functional polymer surfaces that we have designated as “Bottle-Brush Nanoglass” (BB-NG) after the two principle components: (a) a polyoxetane soft block “spine” with side chain “A” bristles and triethoxysilyl chain ends and (b) an alkoxysilane that together with BB chain ends comprise precursors to a “nanoglass”, NG phase. This paper focuses on the extent of modification for a conventional aliphatic polyurethane using a range of fluoropolyoxetane (poly(trifluoroethoxymethyl-methyl oxetane) diol) or 3F diol based modifier concentrations. Upon generating a blend of the polyurethane with the modifier, the BB-NG which is a minor constituent of the blend, phase separates to provide the topmost layer of the coating. Initial results demonstrate that the modified polymer coatings exhibit an expected increase in contact angles with water. Wetting behavior was characterized using the sessile drop technique as well as Dynamic Contact Analysis (DCA, Wilhelmy Plate). Surface composition as well as near surface topology and morphology are characterized by X-ray Photoelectron Spectroscopy (XPS) and Tapping Mode Atomic Force Microscopy (TM-AFM) respectively. Contrast in phase images reflect the surface modulus and viscoelasticity, from which physical form or compositional differences may be deduced. These characteristics have also been explored in our study by hardness tests via nanoindentation.
182

Photocontrôle d'événements de reconnaissance moléculaire au sein de récepteurs greffés sur des surfaces : vers des ardoises supramoléculaires / Photocontrol of recognition events in surface-bound anthracene gated receptors

Liang, Chih-Kai 04 December 2012 (has links)
Des récepteurs de barbiturates greffés avec des groupements anthracène photoactifs possédant différentes fonctions d’ancrage ont été synthétisés et caractérisés, en vue de transférer leurs propriétés de reconnaissance photocontrôlable à des substrats par diverses techniques de modification, comme la formation de liaisons amide, de liaisons thioacétate, ou par réaction click. Les propriétés photophysiques et photochimiques de ces récepteurs ont été étudiées en solution, et la fluorescence, la durée de vie et le rendement quantique ont été mesurés à différentes températures. Des surfaces d’or modifiées ont été fabriquées et caractérisées par ellipsométrie, mesure d’angle de contact, AFM et PM-IRRAS. Les résultats montrent qu’il est possible de moduler les propriétés de reconnaissance moléculaire des récepteurs de manière réversible via une combinaison d’irradiation lumineuse (365 nm) et de chaleur (80 °C). / Anthracene-appended photoactive barbiturate receptors possessing various anchoring groups are synthesized and characterized in view of transferring their photocontrolled binding properties onto substrates through various surface grafting techniques, such as amide bond formation, direct thioacetate linkage, or post click reaction modification. The photophysical and photochemical properties of the synthesized receptors were investigated in solution using variable temperature fluorescence, lifetime measurement and reaction quantum yield measurements. Receptor-modified gold substrates were characterized using ellipsometry, contact angle, AFM and PM-IRRAS experiments. The results showed that it is possible to reversibly modulate the binding properties of the anthracene-appended receptors through a combination of the irradiation with light (365nm) and heat (80℃).
183

De la fonctionnalisation d'une huile végétale aux matériaux polymères bio-sources : étude de lipopolymères en solution et de résines epoxy lipidiques / From the functionalization of a vegetable oil based polymeric materials : study of lipopolymers behavior in solution and oil epoxy resins

Stemmelen, Mylène 05 December 2012 (has links)
Ce travail de thèse examine trois voies de valorisation de l'huile de pépins de raisin au travers de l'élaboration de matériaux polymères auto-associatifs, réticulés ou hybrides. L'huile végétale ou un modèle lipidique (l'oléate de méthyle) sont d'abord fonctionnalisés grâce à leurs insaturations menant à des huiles hydroxylées, aminées, ou phosphorées.Dans une première étude, l'huile et l'oléate de méthyle ont été hydroxylés par réaction thiol-ène. Les alcools gras sont ensuite transformés en macroamorceurs capables d'amorcer la polymérisation cationique par ouverture de cycle de la 2-méthyl-2-oxazoline. Les lipopolymères (LipoPOx) amphiphiles ainsi synthétisés sont capables de s'auto-associer et de former des nanoparticules monodisperses observées par DLS. Dans une deuxième étude, l'huile et certains de ses dérivés amide ont été modifiés sous UV par addition radicalaire du chlorure de cystéamine, conduisant à une diamine linéaire et à une polyamine ramifiée. Ces dernières ont été utilisées comme durcisseurs d'huile époxydée permettant la réticulation de résines époxy à fort taux de carbone biogénique. L'étude thermomécanique par analyse rhéologique montre que ces matériaux thermodurcissables ont des Tg comprises entre -38 et -9°C.Dans une troisième étude, les lipides ont été fonctionnalisés par addition radicalaire de diméthylphosphite par voie photochimique ou thermique. La transformation ultérieure des esters phosphonés en fonctions silylées a rendu ces composés réactifs vis-à-vis du titane et de ses oxydes. L'ancrage de lipides sur des particules de TiO2 ou des feuilles de Titane influe sur leurs propriétés de surface. / This Ph-D work deals with the valorization of grapeseed oil for the preparation of novel and various bio-based polymers. Three pathways are developed starting from lipids and leading to polymeric materials such as self-assembled polymers, thermosets and hybride polymers. First, the vegetable oil and methyloleate were modified using radical addition on their double bonds. Following, hydroxylated, aminated and phosphonated lipids were synthesized.In a first study, the oil was hydroxylated via thiol-ene coupling reaction. The fatty alcohol was then converted into initiator for the cationic ring-opening polymerization of 2-methyl-2-oxazoline. These Lipopolymers so-called LipoPOx exhibit hydrophilic POx block and fatty block. Their amphiphilic nature confer them a self-organization ability in water. A monomodal and narrow distribution of nanoparticles was observed by DLS and AFM.In a second study, the oil and some fatty amides were also functionalized by UV-induced radical addition using cysteamine hydrochloride. A linear diamine and a branched polyamine were synthesized and used as hardeners of epoxidized vegetable oil leading to thermosets with high level of bio-carbone. The investigation on thermo-mechanical properties showed a Tg between -38 and -9°C.In a last study, the lipids were modified by radical addition of dimethylphosphite using thermal or photochemical process. Then, the phosphonate esters were converted into silylated moieties making them reactive toward titanium. The anchoring of lipids onto titanium based materials induced a modification of their surface properties.
184

Digital laser-dyeing : coloration and patterning techniques for polyester textiles

Akiwowo, Kerri January 2015 (has links)
This research explored a Digital Laser Dye (DLD) patterning process as an alternative coloration method within a textile design practice context. An interdisciplinary framework employed to carry out the study involved Optical Engineering, Dyeing Chemistry, Textile Design and Industry Interaction through collaboration with the Society of Dyers and Colourists. In doing so, combined creative, scientific and technical methods facilitated design innovation. Standardized polyester (PET) knitted jersey and plain, woven fabrics were modified with CO2 laser technology in order to engineer dye onto the fabric with high-resolution graphics. The work considered the aesthetic possibilities, production opportunities and environmental potential of the process compared to traditional and existing surface design techniques. Laser-dyed patterns were generated by a digital dyeing technique involving CAD, laser technology and dye practices to enable textile coloration and patterning. An understanding of energy density was used to define the tone of a dye in terms of colour depth in relation to the textile. In doing so, a system for calibrating levels of colour against laser energy in order to build a tonal image was found. Central to the investigation was the consideration of the laser beam spot as a dots-per-inch tool, drawing on the principles used in digital printing processes. It was therefore possible to utilise the beam as an image making instrument for modifying textile fibres with controlled laser energy. Qualitative approaches employed enabled data gathering to incorporate verbal and written dialogue based on first-hand interactions. Documented notes encompassed individual thought and expression which facilitated the ability to reflect when engaged in practical activity. As such, tacit knowledge and designerly intuition, which is implicit by nature, informed extended design experiments and the thematic documentation of samples towards a textile design collection. Quantitative measurement and analysis of the outcomes alongside creative exploration aided both a tacit understanding of, and ability to control processing parameters. This enabled repeatability of results parallel to design development and has established the potential to commercially apply the technique. Sportswear and intimate apparel prototypes produced in the study suggest suitable markets for processing polyester garments in this way.
185

Desenvolvimento do fenótipo osteoblástico em células derivadas de osso alveolar humano cultivadas sobre titânio revestido com colágeno tipo I / Development of the osteoblastic phenotype in human alveolar bone-derived cells grown on a collagen type I-coated titanium surface

Assis, Adriano Freitas de 18 April 2008 (has links)
Os eventos celulares e extracelulares que ocorrem durante o processo de osseointegração do titânio (Ti) são bastante influenciados por suas propriedades de superfície, como morfologia, topografia e composição química. A modificação bioquímica da superfície do Ti consiste em imobilizar proteínas ou peptídeos nessa superfície com a finalidade de induzir respostas celulares e teciduais específicas na interface osso-implante que acelerem ou aumentem a osseointegração. O objetivo deste estudo foi avaliar o desenvolvimento do fenótipo osteoblástico em culturas de células crescidas sobre Ti revestido com colágeno tipo I. Para tanto, células osteoblásticas derivadas de fragmentos ósseos do processo alveolar de humanos foram cultivadas sobre discos de Ti usinados revestidos (Ti-col) ou não (Ti-usinado) com colágeno tipo I e foram avaliados os seguintes parâmetros: adesão, morfologia e proliferação celulares, síntese de proteína total, atividade de fosfatase alcalina (ALP), formação de matriz mineralizada, e expressão de genes marcadores do fenótipo osteoblástico por reação em cadeia da polimerase em tempo real (PCR em tempo real). O Ti-col alterou o crescimento e a expressão gênica das culturas e não teve efeito na adesão e morfologia celulares, síntese de proteína total, atividade de ALP e formação de matriz mineralizada comparado ao Ti-usinado. Esses resultados indicam que a superfície Ti-col pode favorecer um maior crescimento da cultura durante a fase proliferativa e um aumento e/ou aceleração da diferenciação, como indicado por alterações na expressão gênica de marcadores do fenótipo osteoblástico. Portanto, essa modificação de superfície pode ter um impacto nos processos de reparo e remodelação do tecido ósseo adjacente a implantes, favorecendo a ocorrência de maior formação óssea. / Cellular and extracellular events that occur during titanium (Ti) osseointegration process are highly influenced by its surface properties, such as morphology, topography and chemical composition. The objective of biochemical modification of Ti is to immobilize proteins or peptides on its surface in order to induce specific cellular and tissue responses at the boneimplant interface in order to accelerate or enhance osseointegration. The aim of this study was to evaluate the osteoblastic phenotype development in cells grown on collagen type I-coated Ti surface. Osteoblastic cells from human alveolar bone fragments were cultured on turned Ti either coated with collagen type I (col-Ti) or not (turned-Ti) and the following parameters were assessed: cell adhesion, morphology, and proliferation, total protein content, alkaline phosphatase (ALP) activity, bone-like formation and gene expression of osteoblastic markers by real-time polymerase chain reaction (real-time PCR). Col-Ti altered culture growth and gene expression of osteoblastic markers without affecting cell adhesion, morphology, protein synthesis, ALP activity, and matrix mineralization. These results demonstrated that col-Ti favours cell growth during the proliferative phase and osteoblastic differentiation, as demonstrated by changes in mRNA expression profile during the matrix mineralization phase, suggesting that this Ti surface modification may affect the processes of bone healing and remodelling.
186

Nanopartículas magnéticas decoradas com nanopartículas metálicas visando aplicações em biomedicina / Magnetic nanoparticles decorated with metal nanoparticles to applications in biomedicine

Moraes, Daniel Angeli de 23 August 2012 (has links)
A conjugação entre as nanopartículas (NPs) de diferentes materiais, por meio de ligações químicas entre as moléculas orgânicas presentes na superfície das NPs, pode produzir nanoestruturas core-satéllites multifuncionais com potenciais aplicações no campo biomédico. O objetivo deste estudo foi obter nanoestruturas core-satéllites ou conjugadas, com NPs de Fe3O4 e Au, por meio de reações químicas específicas entre moléculas orgânicas presentes nas superfícies das NPs. As NPs de Fe3O4 foram sintetizadas utilizando rotas de decomposição térmica, resultando em NPs com tamanho e forma controlados. O ácido oleico presente na superfície das NPs de Fe3O4, como sintetizadas, foi substituído pelos ligantes, 3-aminopropiltrimetoxisilano (APTMS) ou 3-mercaptopropiltrimetoxisilano (MPTMS). NPs de Au esféricas de 5,7 nm foram sintetizadas pelo método de Brust modificado, e a sua superfície foi modificada usando o ácido mercaptoundecanoico (AMU). A conjugação entre as NPs de Au e Fe3O4 foi realizada por duas vias diferentes. Primeiramente, usando os grupos amina-terminais livres das NPs Fe3O4@APTMS e os grupos carboxilatos das NPs Au@MUA e, depois, com a utilização dos grupos tióis das NPs Fe3O4@MPTMS e as NPs de Au, antes da modificação de superfície. Após a conjugação o comportamento superparamagnético das NPs de Fe3O4 foi preservado, mas a banda plasmon das NPs de Au apresentou um alargamento e um red-shift. Como esperado, a incorporação de materiais não magnéticos nas NPs magnéticas, resultou em uma pequena diminuição na magnetização de saturação em comparação com as NPs como sintetizadas. O alargamento observado na banda plasmon pode ser explicado pela agregação das NPs de Au, no entanto as influências magnéticas não podem ser discutidas. / The conjugation between nanoparticles (NPs) of different materials by using chemical bonds between organic molecules present on NPs surfaces can produce multifunctional core-satellites nanostructures and to provide potential applications in biomedical field. The aim of this study was to obtain core-satellites or conjugated nanostructures with Fe3O4 and Au NPs by specific reactions between organic molecules bonded on NPs surface. The Fe3O4 NPs were synthesized by using thermal decomposition routes leading to size-and shape-controlled NPs. As-synthesized Fe3O4 surface nanoparticles present oleic acid on surface, which was replaced by either (3-aminopropyl)trimethoxysilane (APTMS) or (3-mercaptopropyl)trimethoxylane (MPTMS) ligands. Spherical 5.7 nm Au NPs were synthesized by modified Brust method, and its surface was properly modified by using 11-mercaptoundecanoic acid (MUA). The conjugation between Au and Fe3O4 NPs was performed by two different routes. Firstly, using the free amine-terminal groups from Fe3O4@APTMS and the carboxylates groups from Au@MUA and, secondly, using thiols groups from Fe3O4@MPTMS and as-synthesized naked Au NPs. After conjugation, the superparamagnetic behavior of the Fe3O4 NPs was preserved, but the plasmon band has red-shifted and broadened. As expected the incorporation of non-magnetic materials onto the magnetic NPs, the saturation magnetization presents small decrease compared to as-synthesized NPs. Observed broadening in the plasmonic band can be explained by Au NPs aggregation, but the magnetic influences can not be discussed.
187

Modification of flax fibres for the development of epoxy-based biocomposites : Role of cell wall components and surface treatments on the microstructure and mechanical properties / Modification de fibres de lin pour le développement de bio-composites à matrice époxy : Rôle des composants des parois cellulaires et des traitements de surface sur la microstructure et les propriétés mécaniques

Acera Fernandez, José 15 December 2015 (has links)
Les fibres végétales peuvent être considérées comme une alternative intéressante aux fibres de verre pour la fabrication de matériaux composites. En effet, elles présentent des caractéristiques physiques intéressantes, telles que leur faible densité et leurs bonnes propriétés mécaniques spécifiques, qui peuvent rivaliser avec les composites renforcés de fibres de verre. En outre, les fibres végétales sont obtenues à partir de ressources renouvelables, et présentent généralement moins d'impacts environnementaux lors de leurs phases de production, d’utilisation et en fin de vie. Contrairement aux fibres de verre, les fibres végétales, telles que des fibres de lin, présentent des structures hiérarchiques complexes composées essentiellement de cellulose, hémicellulose, lignine, ciments peptiques et extractibles lipophiliques (cires, acides gras, etc.). Cette composition varie selon les espèces, le lieu et les conditions de croissance, la maturité de la plante, etc. De la même façon, la composition biochimique et la structure des produits et des sous-produits issus du lin sont soumis à de grandes variations selon les étapes successives de transformation réalisées à partir des tiges de lin jusqu’aux fils et tissus. Cela influence fortement les propriétés finales des fibres de lin et de leurs biocomposites. La première partie de cette étude se concentre sur la caractérisation de fibres de lin au cours de leurs étapes successives de transformation. Une homogénéisation de la composition chimique est observée dans les étapes finales de transformation, ainsi qu’une augmentation des propriétés en traction longitudinale des mèches de fibres de lin. La deuxième partie traite de l'utilisation de différents traitements de lavage appliqués sur des tissus d’étoupes de lin et leur influence sur l'extraction des composants de la paroi cellulaire des fibres, ainsi que sur la microstructure et les propriétés mécaniques de biocomposites époxy/lin. Il est montré que les composants de la paroi cellulaire jouent un rôle clé dans la dispersion des mèches et des fibres élémentaires de lin et sur le comportement mécanique transversal de leurs biocomposites. Enfin, l'application de différents traitements de fonctionnalisation sur des tissus de fibre de lin est étudiée afin d'améliorer l'adhérence interfaciale entre les fibres et la matrice. L'utilisation de molécules de type organosilanes (aminosilane, époxysilanes) et de molécules biosourcés (acides aminés et polysaccharides) est étudiée. Une augmentation de la rigidité en traction longitudinale et de la rigidité et de la contrainte maximale en traction transverse est observée en raison de l'amélioration de l'adhésion interfaciale par la fonctionnalisation de surface des fibres avec des molécules d'origine biosourcé et non-biosourcé. / Natural fibres can be considered as a relevant alternative to glass fibres in the manufacture of composite materials. Indeed, they present interesting physical characteristics, such as low density and good specific mechanical properties, which can compete with glass fibre reinforced composites. Moreover, natural fibres are obtained from renewable resources, and generally present lower environmental impacts during their production and use phases and their end of life. Unlike glass fibres, natural fibres, such as flax fibres, are complex hierarchical materials composed essentially of cellulose, hemicellulose, lignin, peptics cements and lipophilic extractives (waxes, fatty acids, etc.). This composition varies among species, collection site, plant maturity, batches, etc. Besides, the biochemical composition and structure of flax products and sub-products undergo wide variations according to the transformation steps from stems to yarns and fabrics. This influences greatly the final properties of flax fibres and their biocomposites. The first part of this study is focused on the characterization of flax fibres during their successive transformation steps. A homogenization of the chemical composition is observed at the final transformation steps, as well as an increment of the longitudinal tensile properties of flax yarns. The second part deals with the use of different washing treatments applied on flax tow fabrics and their influence on the extraction of flax cell wall components and the resulting microstructure and mechanical properties of epoxy/flax fibres reinforced biocomposites. It is shown that cell wall components play a key role in the flax yarns and elementary fibres dispersion and transverse mechanical behaviour of biocomposites. Finally, the application of different functionalization treatments onto flax fibres fabrics is investigated in order to improve the interfacial adhesion between fibres and matrix. The use of non-bio-based organosilane molecules (aminosilane, epoxysilane) and bio-based molecules (amino-acids and polysaccharides) is studied. Improvedstiffness in longitudinal tension test and stiffness and tensile strength in transverse tension test are observed due to the improvement of interfacial adhesion by surface functionalization of the fibres with both bio-based and non-bio-based molecules.
188

Síntese e caracterização de partículas de fosfato de cálcio funcionalizadas com TEGDMA e sua aplicação no desenvolvimento de materiais resinosos remineralizadores / Synthesis and characterization of calcium phosphate particles functionalized with TEGDMA and their application in the development of remineralizing resin-based materials

Rodrigues, Marcela Charantola 24 October 2014 (has links)
Os objetivos deste trabalho foram : 1) sintetizar e caracterizar partículas de fosfato di-cálcico di-hidratado (DCPD) funcionalizadas com dimetacrilato de trietileno glicol (TEGDMA), com o propósito de reduzir a aglomeração e melhorar a interação entre as partículas e a matriz orgânica dos materiais resinosos e 2) avaliar o efeito da adição de partículas funcionalizadas em uma matriz resinosa em relação a liberação de íons, propriedades ópticas, grau de conversão, propriedades mecânicas e microestrutura do material. Na primeira etapa do trabalho foram sintetizadas pelo método sol-gel dois tipos partículas de DCPD: funcionalizadas e puras. Além dessas, caracterizou-se nesta etapa partículas comerciais do mesmo composto. As partículas foram caracterizadas por difração de raio X (DRX), espectroscopia no infravermelho com transformada de Fourier (FTIR), análise elementar, análise termogravimétrica (TGA), isortermas de adsorção de nitrogênio e método BET, microscopia eletrônica de transmissão e espalhamento de luz dinâmico (DLS). Na segunda etapa do trabalho, um novo lote de partículas funcionalizadas foi sintetizado, e como controle, sintetizou-se partículas não funcionalizadas. Quatro materiais resinosos foram formulados, um deles contendo apenas BisGMA e TEGDMA (1:1 em mols) e os demais contendo, além da matriz resinosa, 20% (em volume) de partículas funcionalizadas, partículas não funcionalizadas ou sílica coloidal silanizada. Os materiais foram avaliados quanto à liberação de íons, propriedades ópticas (transmitância total e E em relação à resina sem carga), grau de conversão (GC), resistência à flexão biaxial (RFB), módulo de elasticidade e análise microestrutural. Os dados foram submetidos à análise de variância (ANOVA), complementada pelo teste de Tukey, com nível de significância de 5 %. A composição das partículas foi confirmada por DRX e a funcionalização das mesmas foi confirmada pelas análises de FTIR, análise elementar e TGA. As partículas funcionalizadas apresentaram área superficial até 3 vezes maior quando comparadas às partículas puras e comerciais. Esses dados foram confirmados pela análise de DLS, que encontrou aglomerados maiores para as partículas dos compostos puro e comercial. Na segunda etapa do estudo, observou-se que a funcionalização das partículas não afetou a liberação de íons Ca2+ dos materiais bioativos; entretanto, a liberação de íons HPO42- foi 51% menor para o material contendo partículas funcionalizadas. Todos os materiais apresentaram GC semelhantes. O compósito com sílica apresentou valores de transmitância significantemente menores e E superior ao obtido para os demais materiais. A funcionalização das partículas aumentou a RFB em 32%, porém ainda inferior à do compósito com sílica. A funcionalização não afetou o módulo de elasticidade dos materiais. A síntese de partículas de DCPD funcionalizadas com TEGDMA foi realizada com êxito. O monômero funcionalizante contribuiu para a diminuição do tamanho dos aglomerados. Além disso, a funcionalização favoreceu a interação entre as partículas de DCPD e a matriz orgânica dos materiais, evidenciado pelo aumento no valor de resistência à flexão, sem redução substancial na liberação de íons cálcio do material. / The aims of this study were: 1) to synthesize and characterize dicalcium phosphate dihidrate (DCPD) particles functionalized with triethylene glycol dimethacrylate (TEGDMA), with the purpose of reducing agglomeration and improve the interaction between the particles and the organic matrix of resin-based materials and 2) evaluate the effect of the addition of functionalized particles in a resin matrix regarding ion release, optical properties, degree of conversion, mechanical properties and microstructure. In the first part of the study, two types of DCPD particles were synthesized by a sol-gel method: functionalized and bare. Additionally, proprietary DCPD particles were also characterized. Particles were characterized by X-ray diffraction (DRX), Fourier-transformed infrared spectroscopy (FTIR), elemental analysis, thermogravimetric analysis (TGA), Nitrogen adsorption isotherms and BET method, transmission electron microscopy and dynamic light scattering (DLS). In the second part, a new batch was synthesized and, as a control, non-functionalized nanoparticles were synthesized. Four resin-based materials were prepared, one containing only BisGMA and TEGDMA (1:1 in mols) and the other containing besides the resin, 20 % (in volume) of functionalized, non-functionalized or silanized colloidal silica particles. Materials were evaluated for ion release, optical properties (total transmittance and E, in relation to the unfilled resin), degree of conversion (DC), biaxial flexural strength (BFS), elastic modulus and microstructural analysis. Data were subjected to analysis of variance (ANOVA), complemented by Tukey test, with a global significance level of 5%. Particles composition was confirmed by DRX, while functionalization was confirmed by FTIR , elemental analysis and TGA. Functionalized particles presented surface area up to three times higher compared to bare and proprietary particles. These findings were confirmed by DLS, which found larger agglomerates for the bare and proprietary particles. In the second part of the study, it was observed that particle functionalization did not affect Ca2+ release from the bioactive materials; however, HPO42- release was 51% lower from the material containing functionalized particles. All materials presented similar DC. The silica composite presented transmittance values significantly lower and higher E than the other materials. Functionalization increased BFS in 32%, however, it remained lower than the silica-containing composite. Functionalization did not affect elastic modulus. The synthesis of functionalized particles was accomplished with success. The functionalized monomer contributed for reducing agglomerate size. Also, functionalization favored the interaction between DCPD particles and the resin matrix of the materials, evidenced by the increase in flexural strength, without substantially reducing calcium release from the material.
189

Modificação de superfícies para o uso em cultura de células / Surface modification for use in cell culture

Araujo, Wagner Wlysses Rodrigues de 16 December 2014 (has links)
O projeto de novos materiais para aplicações tecnológicas em biomateriais e bioengenharia é altamente dependente de como as células aderem à superfície de um material. A adesão e crescimento em biomateriais depende de propriedades do substrato, tais como molhabilidade da superfície, a topografia e a composição química de superfície. O objetivo deste estudo foi investigar as interações de diversos materiais com culturas celulares de células epitelial CHO (Ovário de Hamster Chinês). Os materiais utilizados foram SU-8 2005 (elétron-resiste, Microchem), PDMS (Poli (dimetil siloxano), Down Corning), DLC (Diamond-like Carbon) e vidro foi utilizado como referência. Superfícies de vidro, SU-8, PDMS e DLC lisas (planas) e isentas de modificação ou tratamento específico foram avaliadas quanto ao cultivo de células CHO. Valores médios dos fatores de forma (Ff) de 450 células foram calculados para cada uma das culturas realizadas sobre os 4 substratos. Foram obtidos Ff próximos a 0,52 para o vidro, o SU-8 liso e o DLC, demonstrando um bom espraiamento das células nessas superfícies. A superfície de PDMS apresentou valor unitário para o fator de forma (Ff), que está relacionado a um baixo espraiamento das células. A energia de superfície (ES) obtida para o PDMS é compatível com o resultado de fator de forma (Ff), uma vez que o menor valor para ES é coerente com a baixa adesão celular, o que gerou células com elevado fator de forma (Ff). O SU-8 foi modificado por implantação iônica com uma dose de 1,2x1016 átomos/cm2 e a energia de implantação foi de 8 keV, como referência foi utilizada uma superfície lisa de SU-8 sem implantação. Os resultados mostraram que o número de células vivas por unidade de área foi superior na superfície de SU-8 com prata implantada, mostrando o bom desempenho da cultura nesse substrato. As superfícies de DLC modificadas por tratamento com plasma de oxigênio (DLC-O) e com plasma de hexafluoreto de enxofre (DLC-F) foram utilizadas para cultura celular, os resultados de três experimentos independentes de contagem de número de núcleos (marcados com DAPI) por unidade de área confirmaram os resultados obtidos através do teste de viabilidade (marcados com trypan blue). A superfície de DLC-O, apresentou um maior número de núcleos por unidade de área, quando comparado à superfície DLC-F, da mesma forma que nos resultados obtidos pelo teste de viabilidade. As energias de superfície para as amostras de DLC-F e DLC-O indicaram que a superfície DLC-O é mais hidrofílica do que a superfície DLC-F, que está coerente com o que é conhecido da literatura e com os resultados obtidos em nosso trabalho. Cultura de células CHO foram realizadas em superfícies litografadas com estruturas hexagonais periódicas com o parâmetro 2R (diâmetro do círculo inscrito) sendo 12 µm, 30 µm, 80 µm, 280 µm, 560 µm e também em SU-8 liso. Estas superfícies foram caracterizadas por microscopia óptica de fluorescência com relação ao número de núcleos (marcados com o fluoróforo DAPI) por unidade de área, isto é, núcleos/mm2. Obteve-se histogramas com o número médio de núcleos por mm2 em três experimentos independentes, onde o número núcleos/mm2 foi consideravelmente maior para 80 µm. As superfícies contendo cavidades periódicas de 12 µm e 30 µm apresentaram dificuldade para as células CHO aderirem à superfície. Em uma outra etapa realizou-se culturas celulares em triplicata dos substratos com as superfícies 12 µm, 80 µm, 280 µm, 560 µm e também em SU-8 liso. As células em cada uma das superfícies foram analisadas por microscopia óptica (MO) para avaliação da viabilidade celular, utilizando marcador trypan blue. Obteve-se histogramas com os valores médios para o número de células vivas/mm2 para as culturas celulares que corrobora os resultados obtidos no histograma da cultura celular que tiveram os núcleos marcados pelo fluoróforo DAPI. Assim, fica confirmado o melhor desempenho da cultura celular no substrato 80 µm que apresentou o maior número de células vivas/mm2 As micrografias obtidas através de marcação por DAPI foram analisadas através da função de correlação com intuito de se entender como as células estavam organizadas. Isso foi feito para cada uma das superfícies litografadas, 12 µm, 30 µm, 80 µm, 280 µm, 560 µm e também em SU-8 liso. As superfícies dos substratos 80 µm apresentaram os menores valores de distâncias para primeiros e segundos vizinhos, ou seja, as células estão mais próximas umas das outras. As demais superfícies tendem a separar mais as células. Obteve-se também os valores de raio de aglomerado (rc), distância entre os aglomerados (dc) e o número de primeiros vizinhos (Np) através do ajuste da função de correlação. A análise de correlação mostrou com clareza o que não era evidenciado apenas visualizando-se as imagens. Ela mostra que as células, mesmo em SU-8 liso tem a forte tendência de formar aglomerados de células com raio de aproximadamente 45 µm. No caso de substratos lisos, células CHO apresentaram a melhor adesão na superfície do SU-8, seguido do DLC, enquanto que o PDMS foi a pior situação, devido à baixa molhabilidade do material. No caso de superfícies com microestrutura, SU-8 contendo microcavidades hexagonais de 12 e 30 µm mostraram ser as situações mais adversas para o crescimento de células CHO, provavelmente por causa da topografia das cavidades serem de menor tamanho quando comparadas ao tamanho das células CHO. Em vez disso, SU-8, contendo microcavidades hexagonais de 80 µm foi a superfície mais favorável para o crescimento de células CHO. / The design of new materials for technological applications in biomaterials and bioengineering is highly dependent on how the cells adhere to the material surface. The cells adhesion and growth on biomaterials depends on substrate properties such as surface wettability, topography and the chemical composition. The aim of this study was to investigate the interactions of various materials with cell cultures of epithelial cells CHO (Chinese Hamster Ovary). The materials used were SU-8 2005 (electron resists, Microchem), PDMS (poly (dimethyl siloxane), Dow Corning), DLC (Diamond-like Carbon) and glass was used as reference. Unmodified and flat surfaces of glass, SU-8, PDMS and DLC were evaluated for the culture of CHO cells. Form factor (Ff) values were calculated as average of 450 cells for each of the cultures performed on the four substrates. Ff close to 0.52 was obtained for flat surfaces of glass, SU-8 and DLC, showing a good cell spreading on these surfaces. The surface of PDMS presented a form factor (Ff) near unity, which is related to low spreading cell. The surface energy (ES) obtained for the PDMS is coherent with the Ff result, since the smallest value of ES is consistent with the low cell adhesion, which resulted in cells with a high Ff. The SU-8 was modified by ion implantation using a dose of 1.2x1016 atoms/cm2 and an implantation energy of 8 keV, unmodified flat SU-8 was used as a reference. The cell culture results showed that the number of live cells per unit area was greater in the SU-8 surface implanted with silver, showing a good performance in the culture substrate. The DLC surfaces modified by plasma treatment with oxygen (DLC-O) and sulfur hexafluoride (DLC-F) were used for cell culture. The results of three independent experiments, counting the number of nuclei (marked with DAPI) per unit area, confirmed the results obtained by the viability test (marked with trypan-blue). The surface of the DLC-O had higher number of nuclei per unit area when compared to the surface of the DLC-F, similarly to the results obtained for the viability test. The surface energies of the DLC-F and DLC-O samples indicated that the DLC-O surface is more hydrophilic than the DLC-F surface, which is consistent with results obtained with our work and with the literature. CHO cell culture were performed on surfaces with periodic hexagonal structures with the diameter of inscribed circle (2R) given by 12 µm, 30 µm, 80 µm, 280 µm, 560 µm and also on flat SU-8. These surfaces were characterized by fluorescence optical microscopy with respect to the number of nuclei (marked with fluorophore DAPI) per unit area, i.e. nuclei/mm2. Histograms were obtained for the average number of nuclei per mm2 in three independent experiments, where the substrate with periodic hexagonal structures with 2R = 80 µm presented considerably higher nuclei/mm2. Surfaces containing periodic cavities of 2R =12 µm and 30 µm were adverse for CHO cells adhesion. In another approach, cell culture were analyzed by light microscopy (LM) for evaluation of cell viability using trypan-blue marker. This was carried out in triplicate cell culture on substrates with surfaces 12 µm, 80 µm, 280 µm, 560 µm and also on flat SU-8. Histograms were generated for average number of living cells/mm2 for each substrate, which corroborates with the results obtained for the cell culture marked with fluorophore DAPI. Thus, it is confirmed the better performance of the cell culture on substrates with 2R = 80 µm, presenting the highest number of living cells/mm2. The micrographs obtained with cells marked with DAPI were analyzed through the correlation function with the aim of understanding how the cells were organized. This was performed for each of the lithographed surfaces 12 µm, 30 µm, 80 µm, 280 µm, 560 µm and also flat SU-8. The surfaces of the substrates with 2R = 80 µm had the lowest values for length between its neighbors, that is, the cells are closer to each other. The remaining surfaces tend to separate the cells. Also were obtained the cluster radius values (rc), the distance between the clusters (dc) and the number of nearest neighbors (Np) through the correlation function fitting. The correlation analysis clearly showed what was not possible to observe by viewing the images. It shows that the cells, even in flat SU-8, have a strong tendency to form clusters of cells within about 45 micrometers. In the case of flat substrates, CHO cells exhibited better adhesion to the surface of SU-8, followed by the DLC, while the PDMS was worse due to low wettability of the material. In the case of surfaces with microstructures, SU-8 containing hexagonal microstructures of 12 and 30 µm showed to be the most adverse conditions for the CHO cell growth, probably because of the topography of the cavities being smaller in size compared to the size of CHO cells. SU-8 with 80 µm hexagonal microstructures was more favorable surface for the growth of CHO cells.
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Relations structure-propriétés de surfaces carbonées électroactives : impact de la couche organique et du substrat / Structure-properties relationships of electroactive carbon surfaces : impact of organic layer and substrate

Touzé, Ewen 16 November 2018 (has links)
Les nouveaux matériaux carbonés modifiés par des films organiques constituent un domaine de recherche très actif depuis plusieurs décennies. Ces matériaux suscitent un intérêt grandissant dans les secteurs de l’énergie, de la santé et de l’environnement. Afin d’améliorer les performances de ces matériaux, les innovations reposent notamment sur la maîtrise de la fonctionnalisation des surfaces, le contrôle de la stabilité de la couche immobilisée ou encore sur les nouvelles propriétés liées à la modification. Selon les fonctions chimiques greffées, les applications sont multiples : détection et/ou la capture d’éléments chimiques, hydrophobicité, stockage d’énergie électrique ou de gaz ou encore biocompatibilité. Dans ce contexte, les travaux de cette thèse portent sur la modification de surfaces carbonées par différents composés organiques, dans le but d’une part de déterminer les relations structurepropriétés du film déposé et d’autre part d’améliorer les performances de supercondensateurs carbonés. Nos investigations reposent sur la synthèse d’un ensemble de composés conjugués ou non, suivi d’un greffage indirect passant par une construction sur surface ou par greffage direct via l’oxydation d’amine. Ces greffages ont été explorés méthodologiquement afin de déterminer l’impact de la conjugaison au sein du film organique déposé et l’influence de la structure du matériau carboné. Nous montrons également qu’une fonctionnalisation contrôlée sur carbone activé permet d’avoir une meilleure intégration des molécules dans des supercondensateurs carbonés. L’enjeu consiste à mieux comprendre les interactions molécules-substrat au cours de la modification de matériaux. / The new carbon materials modified with organic films has been a very active field of research for several decades. These materials are attracting increasing interest in the fields of energy, health and environmental. In order to improve the performance of these materials, the innovations are based in particular on the control of the functionalization of the surfaces, the control of the stability of the immobilized layer or on the new properties related to the modification. According to the chemical units grafted, the applications are numerous: detection and/or capture of chemical elements, hydrophobicity, storage of electrical energy or gas or also biocompatibility. In this context, the work of this thesis deals with the modification of carbon surfaces by various organic compounds firstly to determine the structureproperties relationships of the deposited film and secondly to improve the performance of carbon supercapacitors. Our investigations are based on the synthesis of conjugated or unconjugated compounds, followed by indirect grafting by build steps or direct grafting via amine oxidation. These grafts were explored methodologically to determine the impact of the conjugation within the deposited organic film and the influence of the structure of carbon material. We also show that controlled activated carbon functionalization allows for better integration of molecules into carbon supercapacitors. The challenge is to understand molecule-substrate interactions during the modification of materials.

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