Foram determinadas as estruturas cristalinas de três 3-fenil-2- izoxazolin-5-ona-4-benzilideno substituídas com potencial atividade antiinflamatória, a partir dos dados difratométricos de raios-X, usando os Métodos Diretos. O refinamento foi obtido pelo método dos Mínimos Quadrados. O composto C16H11NO2 cristalizou no sistema cristalino monoclínico, grupo espacial P21/a, a = 11,786(5) Å, b = 5,745(1) Å, c = 17,862(5) Å, ß = 95,988(5)º, Z = 4, V = 1202,8(12) Å3 . O composto C17H13NO3 cristalizou no sistema cristalino ortorrômbico, grupo espacial Pna21, a = 11,652(5) Å, b = 6,000(5) Å, c = 19,542(5) Å, Z = 4, V = 1366,2(13) Å3. O composto C17H13NO4 cristalizou no sistema cristalino ortorrômbico, grupo espacial Pcab, a = 10,6983(9) Å, b = 12,6111(8) Å, c = 20,926(2) Å, Z = 8, V = 2823,3(4) Å3. Em todas as estruturas verificou-se semelhança estrutural para com a fenilbutazona. / The crystal structures of three substituted 3-phenyl-2- isoxazolin-5-one-4-benzilidene with potential biological activities have been determined from diffractometric X ray data using the Direct Method. The refinement has been obtained through the least squares method. The compound C16H11NO2 crystallized in the monoclinic crystal system, space group P21/a, a = 11,786(5) Å, b = 5,745(1) Å, c = 17,862(5) Å, ß = 5,988(5)º, Z = 4, V = 1202,8(12) Å3. The compound C17H13NO3 belongs to the orthorhombic crystal system, space group Pna21, a = 11,652(5) Å, b = 6,000(5) Å, c = 19,542(5) Å, Z = 4, V = 1366,2(13) Å3. The compound C17H13NO4 crystallized in the orthorhombic crystal system, space group Pcab, a = 10,6983(9) Å, b = 12,6111(8) Å, c = 20,926(2) Å, Z = 8, V = 2823,3(4) Å3. All these structures show structural similarities to the phenylbutazone.

As tecnologias usualmente aplicadas no mercado fotovoltaico mundial são, em sua maioria, voltadas aos painéis rígidos de células de silício cristalino, em função da redução de seus preços proporcionada pela economia de escala. No entanto, a crescente demanda no País de novos domicílios, principalmente de apartamentos, tem exigido soluções mais apropriadas: com menor ocupação de área horizontal e instaladas na fachada dos edifícios. Nesse sentido vão surgindo tecnologias fotovoltaicas como as de filmes finos como soluções mais apropriadas do que as emergentes de terceira geração, pelo fato dessas últimas ainda se encontrarem em fase de maturação técnica com poucas opções de fornecimento no mercado em nível comercial. Portanto, a abordagem desta dissertação se limitou às tecnologias de filmes finos e de vidros fotovoltaicos semi transparentes, além daquela mais usual que é a de silício cristalino. Contudo, o dinamismo do mercado mundial vem estimulando uma evolução no fator de desempenho dessas tecnologias, o que justificou a necessidade de uma revisão bibliográfica. Além disso, a maioria dos projetos fotovoltaicos vem adotando como base os painéis rígidos com células de silício cristalino, sem, no entanto, avaliarem alternativas com a aplicação de outras tecnologias. O que se nota é a falta de conhecimento mais profundo dos projetistas sobre as tecnologias de filmes finos e das melhores opções para sua aplicação em um edifício, no que tange ao seu desempenho e seu comportamento dentro do espectro de frequência. Assim, esta dissertação teve por objetivo contribuir com uma análise de desempenho energético com base em simulações para tomada de decisão técnica sobre as tecnologias mais adequadas de célula fotovoltaica para sistemas a serem instalados em fachadas de edifícios, auxiliadas por uma ferramenta computacional existente no mercado, o PVSYST. A tomada de decisão foi vista pela perspectiva de desempenho na geração de energia elétrica, pela análise comparativa dos resultados de simulações aplicadas na fachada de um edifício hipotético em São Paulo. Os resultados mostraram que as tecnologias baseadas no silício cristalino são as mais adequadas nos casos em que o pico de demanda de energia no ano seja no verão, como nos edifícios comerciais. Já os sistemas compostos pelos filmes finos do grupo do seleneto de índio e cobre são os mais indicados para os edifícios residenciais, em que o período de maior demanda é no inverno. / Technologies commonly applied in the global photovoltaic market are mostly with the rigid panels of crystalline silicon cells, due to the reduction of their prices provided by economies of scale. However, growing demand in the country of new housing units, mainly apartments, has required more appropriated solutions: with lower occupancy of horizontal area and installed on the building\'s facade. In this direction photovoltaic technologies are emerging such as thin films as better solutions than the emerging technologies of third generation, because still they are in technical maturation phase with few options of suppliers in the commercial market. Therefore, the approach of this dissertation was limited to technologies of thin films and semitransparent photovoltaic glazing, in addition to the more usual one that is crystalline silicon. However, the dynamism of the global market has stimulated an evolution in the performance factor of these technologies, which justified the necessity of literature review. Furthermore, most PV projects have been based on the rigid panels with crystalline silicon cells, not considering the alternatives using other technologies. What is noticed is the lack of deeper understanding of the designers about the thin film technologies and the best options for their application in a building, in terms of their performance and their behavior within the frequency spectrum. Thus, this work aimed to contribute to an energy performance analysis based on simulations for technical decision on the most appropriate photovoltaic cell technologies for systems to be installed on the facades of buildings, aided by an existing software tool on the market, PVSYST. Decision making was seen from the perspective of performance in electricity generation, by comparative analysis of simulations results applied on the facade of a hypothetical building in São Paulo. The results showed that the technologies based on crystalline silicon are the most appropriate in cases where energy demand peak in the year is in the summer, as in commercial buildings. On the other hand, the systems composed of the thin films based on indium and copper selenium group are the most suitable for residential buildings, where the period of greatest demand is in the winter.

La miniaturisation des pièces est une étape importante pour la progression de la microtechnologie dans plusieurs domaines (connectique, médical, optique, microsystèmes mécaniques). Pour cela, le moulage par microinjection, semble être la solution clé pour la production à grande échelle de micro-composants de polymères. Pour les polymères semi-cristallins, la cristallisation, sous fort taux de cisaillement et sous des vitesses de refroidissement élevées (about 100 K/s), induit des morphologies et des propriétés spécifiques. Elle prend donc une importance considérable dans le processus de microinjection par rapport au moulage par injection classique où les épaisseurs injectées sont généralement supérieures à 1 mm. Ces microstructures ont une grande influence sur les propriétés mécaniques du produit final. La prédiction de ces propriétés à partir de la description de la microstructure est un défi technique et scientifique. Durant cette thèse, deux polymères semi-cristallins ont été microinjectés, le polyéthylène haute densité et le polyamide 12. Les analyses obtenues par la microscopie otiques montrent que les morphologies cristallines varient entre les micro- et les macro-pièces. Tandis que la morphologie de ‘peau-cœur' est présente dans les macropièces, les micropièces présentent une morphologie plutôt particulière. Les analyses combinées de diffusion et de diffraction des rayons X (SAXS et WAXS) avec un microfaisceau synchrotron, nous ont permis de déterminer la microstructure induite par le processus de microinjection dans toute l'épaisseur des pièces. Nous avons constaté que la morphologie et les orientations cristallines induites sont très dépendantes des conditions d'injection ou de microinjection. Une diminution de l'épaisseur, de la vitesse et de la température du moule, augmente l'orientation cristalline en limitant la relaxation des chaînes de polymères. / The components miniaturization is an important step in the evolution of micro technology in several domain (connectivity, medical, optical, mechanical, microsystems). For this purpose, the micro-injection molding seems to be the key solution for the large-scale micro-polymer components production.The crystallization of the semi-crystalline polymers under high shear and cooling rates (about 100 K / s), induces specific properties and morphologies, consequently, it takes a substantial importance in the process of micro-injection compared to conventional injection molding where the usually injected thicknesses is over 1 mm. These micro-structures have a great influence on the mechanical propertie of the final product. The prediction of the final product's properties based on the illustration of the micro-structure is a technical and scientific challenge. In this thesis, two semi-crystalline polymers were micro-injected, the high density polyethylene and the polyamide 12. The obtained analyzes with the use of an optical microscope showed that the Morphology of Crystals vary between micro-and macro-pieces. While the morphology of 'peau-cœur' is present in the macro-pieces, the micro-parts have a particular morphology. The combined analysis of diffusion and X-ray diffraction (WAXS and SAXS) along with the synchrotron microbeam, has allowed us to determined the micro-structure induced by the micro-injection process throughout the thickness of the pieces.We have identified that the morphology and the induced crystal's orientation are very dependent on the conditions of injection or micro-injection. The decrease of the thickness,speed and temperature of the mold will increase the crystal orientation by limiting the relaxation of the polymer chains.

Comme je suis particulièrement intéressé par les nanosciences et les nombreuses applications des nanotechnologies, je me suis penché sur le développement de méthodes de fabrication de nanoparticules ultra-petites dont les fonctions peuvent être ajustées avec précision. Récemment, une nouvelle technologie appelée « technologie d’une seule chaîne », c’est-à-dire qui utilise une seule chaîne polymère, est devenue un sujet de recherche de plus en plus motivant pour la communauté scientifique. Cette technologie a l’avantage de dépendre d’une méthode facile de préparation de nanoparticules polymères d’une seule chaîne (SCNPs) et ayant des dimensions typiques de 1,5 à 20 nm. Leurs tailles ultra petites leur confèrent des propriétés spécifiques, ce qui permet de les utiliser comme capteurs, systèmes catalytiques, revêtements à faible viscosité, nanoréacteurs ou pour des applications biomédicales. Grâce aux contributions de nombreux scientifiques durant la dernière décennie, les méthodes de synthèse des SCNPs sont devenues très variées et représentent une technologie désormais mature. Néanmoins, de nombreux problèmes sont à résoudre dans ce domaine, ce qui permettra d’ajouter de nouvelles fonctions ou de les valoriser pour de nouvelles applications. Les polymères sensibles à plusieurs stimuli sont une classe de matériaux intelligents dont les propriétés peuvent être modifiées par l’application d’un stimulus extérieur. Ils sont utilisés extensivement dans les domaines énergétique et biomédical. Comme leurs propriétés physiques et chimiques peuvent être modifiées aisément et efficacement par un contrôle de leur environnement externe, ces polymères sont des candidats pour fabriquer de nouvelles SCNPs. Dans cette thèse, nous nous sommes intéressés au développement de SCNPs ayant de multiples fonctionnalités car cela permet d’ouvrir la voie pour de nouvelles applications. Pour cela, de nombreux polymères sensibles à plusieurs stimuli ont été préparés comme précurseurs à des SCNPs. En concevant spécifiquement ces polymères, il fut possible d’ajouter leurs propriétés de réponse à des stimuli dans les systèmes SCNPs. Le cœur même de cette thèse consiste en trois projets qui utilisèrent trois classes de SCNPs provenant de polymères sensibles aux stimuli. Grâce à leur réponse à plusieurs stimuli, ces SCNPs remplirent de nombreuses fonctions et subirent des modifications soit de leur structure, soit de leur morphologie, soit de leurs propriétés. Et en plus de la variété de fonctions, chaque classe de SCNPs a le potentiel pour de nombreuses applications. Dans la première étude présentée dans cette thèse (chapitre 1), nous avons préparé une classe de SCNPs photodégradables ayant une taille ajustable et inférieure à 10 nm. Il s’agit de polyesters rendus photosensibles par la présence de coumarines à l’intérieur de la chaîne principale (nommés CAPPG) grâce à la copolymérisation de coumarine diol, d’acide adipique et de propylène glycol (PPG). Cette incorporation de coumarines dans la chaîne principale permet au polymère d’être photosensible par deux façons. En effet, les coumarines peuvent se photo-dimériser, lorsqu’elles sont irradiées par des rayonnements UV (> 320 nm) en des cyclobutanes qui peuvent être ouverts à nouveau par d’autres rayonnements UV (254 nm) permettant la restauration des coumarines initiales. Cela a permis la création de SCNPs de tailles inférieures à 10 nm et incluant des propriétés de photodégradation. Cette propriété a été démontrée par une irradiation de 3 h avec des chaînes polymères de 13220 g/mol à 1385 g/mol dans les SCNPs. La taille de ces SNCPs (caractérisée par leur rayon hydrodynamique) peut être modifiée entre 3 nm et 5,3 nm en modifiant le taux de dimérisation des coumarines, ce qui est aisément obtenu en ajustant le temps d’irradiation UV. Les résultats ont démontré que cette méthode permet un contrôle aisé de la taille des SCNPs sans avoir recours à la synthèse de nombreux polymères précurseurs. Finalement, comme le polyester était biodégradable et biocompatible, ces SCNPs peuvent être exploitées pour des applications biomédicales. Dans la deuxième étude effectuée au cours de cette thèse (chapitre 2), nous avons préparé un nouveau type de SCNPs multifonctionnel à partir d’un polymère cristallin liquide. Il s’agit du polyméthacrylate de [2- (7-méthylcoumaryl) oxyéthyle - co - 6-[4-(4’-méthoxyphenylazo) phénoxy] hexyle] (PAzoMACMA). Les groupements latéraux du polymère contiennent, en majorité, des azobenzènes photoisomérisables et, en minorité, des coumarines photodimérisables. Les azobenzènes servent de mésogènes pour la formation de cristaux liquides alors que les coumarines ont été utilisées pour une réticulation photoinduite et intrachaîne. Malgré les dimensions inférieures à 15 nm, le confinement et la réticulation, les phases cristallines liquides (LC) persistèrent même dans les SCNPs. Ces SCNPs cristaux liquides (LC-SCNPs) présentèrent un certain nombre de propriétés intéressantes et particulières. Alors que leurs dispersions dans le THF n’étaient pas fluorescentes, celles dans le chloroforme l’étaient. En plus, ces nanoparticules s’aggloméraient quelque peu dans le chloroforme ce qui induisait des fluorescences différentes entre des SCNPs riches en isomères cis ou riches en isomères trans des azobenzènes. A cause de la photoisomérisation des azobenzènes, ces LC-SCNPs se déformaient sous irradiation comme le font les microparticules ou les colloïdes contenant des azobenzènes. Cependant, la déformation de ces nanoparticules dépend de la longueur d’onde de lumière polarisée. Alors que sous irradiation UV polarisée à 365 nm, l’élongation des SCNPs était perpendiculaire à la polarisation de la lumière incidente, sous irradiation visible polarisée entre 400 et 500 nm, l’étirement se faisait parallèlement à la polarisation. Finalement, un nanocomposite fut préparé par dispersion de LC-SCNPs dans une matrice de polyméthacrylate de méthyle (PMMA). Si celui-ci était étiré mécaniquement, les azobenzènes s’orientaient dans la direction de la déformation induite. Ces propriétés intéressantes des LC-SCNPs que cette étude a permis de dévoiler, suggèrent de nouvelles applications potentielles. Dans la troisième étude de cette thèse (chapitre 3), nous avons préparé une classe de SCNPs sensibles à la présence de CO2 et leurs agrégats micellaires auto-assemblés. D’un côté, des SCNPs ont été préparées à partir d’un polyméthacrylate de {(N, N-diméthylaminoéthyle)-co-4-méthyl-[7-(méthacryloyl)-oxyéthyl-oxy] coumaryle} (PDMAEMA-co-CMA). Lorsqu’elles sont dispersées en solution aqueuse, les nanoparticules individuelles peuvent subir des cycles réversibles d’expansion et de rétrécissement sous une stimulation alternative de CO2 et de N2 qui vont protoner et déprotoner les amines tertiaires. D’un autre côté, des SCNPs de type ‘Janus’ (SCJNPs) ont été préparées à partir d’un copolymère dibloc amphiphile : PS-b-P(DMAEMA-co-CMA) (PS correspond au polystyrène qui est hydrophobe). Ce type de SCJNPs peut s’autoassembler sous forme de micelles en solution aqueuse. Sous stimulation CO2 ou N2, l’expansion ou le rétrécissement à l’intérieur des particules permet de grands changements de volume. En plus, ces particules ont été étudiées comme potentiels nanoréacteurs pour des nanoparticules d’or (AuNPs) que ce soit sous formes SCNPs ou micelles SCJNPs. La vitesse de formation des AuNPs augmente sous bullage de CO2 et décroît sous N2. Cela permet de rendre possible cette réaction contrôlable par ces deux gaz. Qui plus est, utiliser des micelles de SCJNPs dont le volume peut être modifié sur un large intervalle en changeant l’intensité de la stimulation de CO2, permit d’obtenir des AuNPs de taille variable. / Abstract : With interests on nanoscience and nanotechnology for many applications, there is a demand for development of fabrication technology of ultra-small nano-size objects that allow for precise size control and tailored functionality. Recently, a new technology called ‘single-chain technology’, which manipulates a single polymer chain, becomes a rapidly-growing research topic. This technology provides a facile method to prepare polymer single-chain nanoparticles (SCNPs) with a typical size of 1.5-20 nm. Due to the ultra-small size-enabled unique properties, SCNPs have wide range of applications, including sensor, catalytic system, low viscosity coating, nanoreactor and biomedical applications. Through the contributions by many scientists in the past decade, the synthetic methodologies to fabricate SCNPs have been reported using various chemistries and been getting mature. However, there are still several unsolved problems in the field of SCNPs including functions and application. Stimuli-responsive polymers, as a class of smart materials whose properties can be changed by responding to external stimuli, have been widely used in energy and biomedical applications. Since their chemical and physical properties can be changed easily and efficiently via environmental control, stimuli-responsive polymers provide a potential pathway to preparing functional SCNPs. In this thesis, we are focusing on developing functional SCNPs, especially systems with multi-functions, and expanding their applications. To achieve this target, various stimuli-responsive polymers were prepared as polymer precursors and their stimuli-responsive properties were introduced into the SCNP systems by rational design of their chemical structures. The core of this thesis is comprised of three projects which deal with three classes of SCNPs from stimuli-responsive polymers. These stimuli-responsive SCNPs perform multi-functions and undergo certain change either in structure or morphology and properties. In addition, according to their variety of functions, each class of multi-functional SCNPs has diverse potential applications. In the first study presented in the thesis (Chapter 1), we prepared a class of sub-10 nm photodegradable and size-tunable SCNPs based on photo-responsive main-chain coumarin-based polyesters Poly{[7-(hydroxypropoxy)-4-(hydroxymethyl)coumarin adipate]-co- (polypropylene glycol adipate)} (CAPPG) through copolymerization of coumarin diol, adipic acid and polypropylene glycol (PPG). By incorporating coumarin moieties into the chain backbone of a polyester, dual photo-responsive reaction, i.e. photo-dimerization (>320 nm) and photo-induced chain scission (254 nm), occur under two different wavelengths of UV irradiation, enabling the preparation of sub-10 nm SCNPs and their photo-degradation property. The photo-degradability of SCNPs is evidenced under 254 nm UV irradiation for 3 h, which molecular weight of SCNPs decreasing from 13220 g/mol to 1385 g/mol. Moreover, the size of SCNPs can be tunable from 5.3 nm to 3 nm (hydrodynamic diameter) by varying the dimerization degree of coumarin moieties, that is simply controlled by the UV irradiation time. These results demonstrate a facile method to control the size of SCNPs without the need for synthesizing different polymer precursors. Finally, due to the biocompatible and biodegradable nature of polyester as polymer precursor, the SCNPs with photo-degradability and size-tunability have the potential to be exploited for biomedical applications. In the second study realized in this thesis (Chapter 2), we prepared a new type of multi-functional SCNPs from a side-chain liquid crystalline polymer (SCLCP), namely poly{6-[4-(4-methoxyphenylazo) phenoxy]hexylmethacrylate-co-4-methyl-[7-(methacr-yloyl) oxy-ethyl-oxy]coumarin} (PAzoMACMA). The polymer’s side groups comprise photo-isomerizable azobenzene in majority and photo-dimerizable coumarin in minority, with the former as mesogens and the latter for intra-chain photo-crosslinking. Despite the sub-15 nm size, confinement and crosslinking, the liquid crystalline (LC) phases of bulk PAzoMACMA persist in SCLCPs. Such LC-SCNPs exhibit a number of interesting and peculiar properties. While their dispersion in THF is non-fluorescent, when dispersed in chloroform, the nanoparticles appear to agglomerate to certain degree and display significant fluorescence that is different for SCNPs rich in the trans or cis isomer of azobenzene. The azobenzene LC-SCNPs also undergo photo-induced deformation, similar to azobenzene micro- or colloidal particles. However, the elongational deformation of the nanoparticles is dependent upon the linearly polarized excitation wavelength. While under polarized 365 nm UV irradiation the SCNP stretching direction is perpendicular to the light polarization, under polarized 400-500 nm visible light irradiation, the stretching takes place along the light polarization direction. Finally, an all-polymer nanocomposite was prepared by dispersing the LC-SCNPs in poly(methyl methacrylate) (PMMA), and mechanically stretching-induced orientation of azobenzene mesogens developed along the strain direction. The interesting properties of LC-SCNPs unveiled in this study suggest new possibilities for applications including bio-imaging and LC materials. As the third study in this thesis (Chapter 3), we studied a class of CO2-responsive SCNPs and their self-assembled micellar aggregates. On one hand, SCNPs are prepared from a random copolymer of poly{(N,N-dimethylaminoethyl methacrylate)-co-4-methyl-[7-(methacryloyl)oxyethyl-oxy]coumarin} (P(DMAEMA-co-CMA)). When dispersed in aqueous solution, individual nanoparticles can undergo reversible swelling/shrinking under alternating CO2/N2 stimulation as a result of the reversible protonation/deprotonation of tertiary amine groups. On the other hand, tadpole-like single-chain ‘Janus’ nanoparticles (SCJNPs) are prepared using an amphiphilic diblock copolymer of PS-b-P(DMAEMA-co-CMA) (PS is hydrophobic polystyrene). This type of SCJNPs can self-assemble into core-shell micellar aggregates in aqueous solution. Under CO2/N2 stimulation, the collective swelling/shrinking of SCJNPs within the micelle results in large, reversible volume change. In addition, both P(DMAEMA-co-CMA) SCNPs and PS-b-P(DMAEMA-co-CMA) SCJNP micelles are explored as gas-tunable nanoreactors for gold nanoparticles (AuNPs). The rate of AuNP formation increases under CO2 stimulation and decreases upon N2 bubbling, which makes it possible to tune the reaction rate up and down (on/off switching) by using the two gases. Moreover, using the micelles of SCJNPs, whose volume can be controlled over a wide range by adjusting the CO2 stimulation strength, variable-size AuNPs and their aggregates are obtained with continuous redshift of the surface plasmon resonance (SPR) into the long wavelength visible light region.

Controlling conformation of macromolecules, both in solution and solid state, has remained an exciting challenge till date as it confronts the entropy driven random coil conformation. Folded forms of biomacromolecules, like proteins and nucleic acids, have served as role-models to the scientists in terms of designing synthetic foldamers. The folded functional forms of proteins and nucleic acids have been shown to rely heavily on various factors, like directional hydrogen bonding, intrinsic conformational preferences of the backbone, solvation (e.g. hydrophobic effects), coulombic interactions, charge-transfer interactions, metal-ion complexation, etc. Chapter-1 discusses various designs of synthetic polymers explored by research groups world-over to emulate the exquisite conformational control exercised by biomacromolecular systems. Our laboratory has been extensively involved since 2004 in designing charge-transfer complexation induced folding of flexible donor-acceptor (DA) polymeric systems, such as those shown in Scheme 1. It was observed that such polymers adopt a folded conformation in polar solvents, like methanol, in the presence of an excess of an appropriate alkali metal ion. To explore folding in the solid state, Jonas and co-workers recently showed that a polyethylene-like polyester with long alkylene segments containing periodically located pendant propyl group forms a semicrystalline morphology with alternating crystalline and amorphous regions primarily because of the periodic folding of the backbone due to the steric exclusion of the propyl branches from the crystalline domains. In order to explore immiscibility-driven folding of polyethylene-like polyesters, Roy et al. designed a periodically grafted amphiphilic copolymer (PGAC) containing long alkylene segments (mimicking polyethylene) and pendant oligoethyleneglycol chains at periodic intervals (Scheme 2). Scheme 2: Proposed folding of a periodically grafted amphiphilic copolymer It was demonstrated that immiscibility between the hydrocarbon backbone and pendant PEG segments drives the polymer to adopt a folded zigzag conformation as shown in Scheme 2. The above synthetic strategy, however, does not permit easy structural variation of the side chain segments because the side-chain segment is covalently linked to the malonate monomer. In Chapter-2, a more general strategy to prepare periodically grafted copolymers has been described. In an effort to do so, we designed a series of clickable polyesters carrying propargyl/allyl functionality at regular intervals along the polymer backbone, as shown in Scheme 3. Scheme 3: Periodically clickable polyesters for the preparation of periodically grafted copolymers The polyesters were prepared by reacting either 2-propargyl-1,3-propanediol, 2,2-dipropargyl-1,3-propanediol or 2-allyl-2-propargyl-1,3-propanediol with an alkylene diacid chloride, namely 1,20-eicosanedioic acid chloride, under solution polycondensation conditions. Since these polyesters carry either, one propargyl, two propargyls or one propargyl and one allyl group on every repeat unit, it provides us an opportunity to synthesise exact graft copolymers with one side chain, two side chains or even two dissimilar side chains per repeat unit. In Chapter-3, the periodically clickable polyesters were reacted with MPEG-350 (PEG 350 monomethyl ether) azides using Cu(I) catalyzed azide-yne click reaction to generate periodically grafted amphiphilic copolymers (PGAC) carrying crystallizable hydrophobic backbone and pendant hydrophilic MPEG-350 side-chains (Scheme 4). Since the PGACs carry either one or two pendant MPEG-350 chains on every repeat unit, it allowed us to examine the effect of steric crowding on the crystallization propensity of the central alkylene segment. Scheme 4: Functionalization of periodically clickable polyesters with MPEG 350 azide by azide-yne click reaction From DSC studies, it was observed that increase in steric crowding at junctions resulting from increased side-chain volume hinders effective packing of the hydrocarbon backbone. As a result, both transition temperatures and the enthalpies associated with these transitions decreases. SAXS and AFM studies revealed the formation of lamellar morphology with alternate domains of PEG and hydrocarbon. Based on these observations, we proposed that self-segregation between hydrophobic backbone and hydrophilic side-chains induce the backbone to adopt a folded zigzag conformation (Scheme 5). Scheme 5: Schematic depiction of self-segregation induced folding of PGAC and their assembly on mica surface (AFM image) In order to study the effect of solvent polarity on conformational evolution of the periodically grafted amphiphilic copolymers, we randomly incorporated pyrene in the backbone of the polymer by reacting a small fraction (~ 5 mole %) of the propargyl groups with pyrene azide. Fluorescence study of the pyrene labelled polymer showed that increase in solvent polarity increases the intensity of the excimer band dramatically; this suggests the possible collapse of the polymer chain to the folded zigzag form. In an extension of this work, the PGAC was further used as template to synthesise layered silicates that appears to replicate the lamellar periodicity seen in the polymer. In order to study the effect of reversing the amphiphilicity on self-segregation, in Chapter-4, we synthesised a series of clickable polyesters carrying PEG segments of varying lengths, namely PEG 300, PEG 600 and PEG 1000, along the polymer backbone. The polymers were prepared by trans-esterification of 2-propargyl dihexylmalonate with different PEG-diols. These polyesters were then clicked with docosyl (C22) azide using Cu(I) catalyzed azide-yne click reaction to generate the desired periodically grafted amphiphilic polymers carrying crystallizable hydrophobic pendant chains at periodic intervals; the periodicity in this case was governed by the length of the PEG diols (Scheme 6). Scheme 6: PGACs carrying hydrophilic PEG backbone and crystallizable hydrophobic pendant docosyl chains Varying the average periodicity of grafting provided an opportunity to examine its consequences on the self-segregation behavior. Given the strong tendency of the pendant docosyl segments to crystallize, DSC studies proved useful to analyse the self-segregation; DOCOPEG 300 clearly exhibited the most effective self-segregation, whereas both DOCOPEG 600 and DOCOPEG 1000 showed weaker segregation. Based on the observations from DSC studies, we proposed that the PEG backbone adopts a hairpin like conformation (Scheme 7). Scheme 7: Proposed self-segregation through hairpin like conformation of backbone PEG segments In order to confirm the bulk morphology, we carried out small angle X-ray scattering (SAXS) and atomic force microscopic (AFM) studies. The SAXS profiles confirmed the observations from DSC studies, and only DOCOPEG 300 exhibited well-defined lamellar ordering. Thus, it is clear that the length of the backbone PEG segment (volume-fraction) strongly influences the morphology of the PGACs. Based on the inter-lamellar spacing from SAXS and the height measurements from AFM studies (Scheme 8), we proposed that these polymers form lamellar morphology through inter-digitation of the pendant docosyl side-chains. The observations from Chapters 3 and 4 suggested that the crystallization of the backbone has a dramatic effect on the conformation of the polymer backbone. In order to explore the possibility of independent crystallization of both backbone and pendant side-chains, the periodically clickable polyesters, described in Chapter-2, were quantitatively reacted with a fluoroalkyl azide, namely CF3(CF2)7CH2CH2N3 using Cu(I) catalyzed azide-yne click reaction; Chapter-5 describes these polyesters carrying long chain alkylene segments along the backbone and either one or two perfluoroalkyl segments located at periodic intervals along the polymer chain (Scheme 9). DSC thermograms of two of the samples showed two distinct endotherms associated with the melting of the individual domains, while the WAXS patterns confirm the existence of two separate peaks corresponding to the inter-chain distances within the crystalline lattices of the hydrocarbon (HC) and fluorocarbon (FC) domains; this confirmed the occurrence of independent crystallization of both the backbone and side chains. Scheme 10: Left-variation of SAXS profile of all three polymers as a function of temperature, Right- molecular modelling of representative FC-HC-FC triblock structures. Interestingly, a smectic-type liquid crystalline phase was observed at temperatures between the two melting transitions. SAXS data, on the other hand, revealed the formation of an extended lamellar morphology with alternating domains of HC and FC (Scheme 10). The inter-lamellar spacing calculated from SAXS matches reasonably well with those estimated from TEM images. Based on these observations, we proposed that the FC modified polymers adopt a folded zigzag conformation whereby the backbone alkylene (HC) segment becomes colocated at the center and is flanked by the perfluoroalkyl (FC) groups on either side, as depicted in Scheme 11. Melting of alternate HC domains first leads to the formation of a smectic-type liquid crystalline mesophase, wherein the crystalline FC domains retain the smectic ordering; this was confirmed by polarizing light microscopic observations. Scheme 11: Schematic presentation of self-segregation induced folding of polymer chains; and hence crystallization assisted assembly of these singly folded chains to form lamellar structure One interesting challenge would be to create unsymmetrical folded structures, wherein the top and bottom segments of the zigzag folded form would be occupied by two different segments, such as PEG and FC, whereas the backbone alkylene segment would form the central domain; this would lead to the possible formation of consecutive domains of PEG, HC and FC through immiscibility driven self-segregation process. In Chapter-6, several approaches to access such systems have been described; one such design that could have resulted in the successful synthesis of a periodically clickable polymer carrying orthogonally clickable propargyl and allyl groups along the backbone in an alternating fashion is depicted in (Scheme 12). The parent polyester was successfully synthesized and the propargyl group was first clicked with the FC-azide to yield the FC-clicked polyester; however, several attempts to click MPEG-SH onto the allyl groups using thiol-ene click reaction failed. Scheme 12: Scheme for the synthesis of alternating orthogonally clickable polymer In order to accomplish our final objective, we chose to first prepare the FC-clicked diacid chloride and polymerize it with an azide-alkyne clickable macro-diol, as depicted in Scheme 13; this approach was successful and yielded the desired clickable polyester bearing the FC segments at every alternate location. This polymer was then clicked with PEG-750 azide to yield the final targeted polymer that carries mutually immiscible FC and PEG-750 segments at alternating positions along the polymer backbone. The occurrence of self-segregation of FC, PEG-750 and the alkylene backbone (HC) was first examined by DSC studies, which appeared to suggest the presence of three peaks, although these were not very well-resolved. Scheme 13: Schematic for the synthesis of the polymer carrying FC and PEG 750 alternatingly along the backbone A schematic depiction of the anticipated organization of such unsymmetric folded macromolecules is shown in Scheme 15; it is evident that because of mutual immiscibility, the layers will be organized such that the FC domains of adjacent layers will be together and similarly the PEG domains of adjacent layers will also be together. Such an organization would lead to an estimated spacing that would correspond to a bilayer of the folded structures. Interestingly, SAXS study (Scheme 14) reveals the formation of lamellar morphology with a d-spacing of 14.6 nm. Scheme 14: Figure 6.10: SAXS profile of the polymer PE-FC-PEG 750 In order to gain an estimate of the expected inter-lamellar spacing, the end-to-end distance of a model repeat-unit was computed to be ~ 9.4 nm. It is, therefore, evident that the inter-lamellar spacing of 14.6 nm seen in the SAXS is significantly larger and must represent a bilayer type organization (Scheme 15). In this regard it is important to say that the organization of these alternatingly functionalized folded chains should give a variety of d-spacings. Because of highest electron density contrast of FC among PEG, HC and FC, we proposed that the d-spacing calculated from the SAXS profile corresponds to ‘d4’ in Scheme 15. This first demonstration of the formation of zigzag folded unsymmetric entities bearing dissimilar segments on either side of the folded chain holds exciting potential for a variety of different applications and beckons further investigations. Scheme 15: Schematic for the proposed self-assembly of the singly folded polymer chains

Les critères de localisation et d’endommagement sont généralement basés sur un cadre dissipatif et ce travail s’intéresse aux couplages thermomécaniques accompagnant les micromécanismes de déformation. Il repose en partie sur des données expérimentales obtenues précédemment dans le laboratoire par Bodelot pour un polycristal d’acier A316L. Ce travail tire profit d'une combinaison de techniques différentes, en particulier de mesures in situ de champs cinématiques et thermiques ainsi que de l’Orientation Imaging Microscopy, de la profilométrie et d’une micrographie de surface. Différents outils ont été développés afin (1) d'identifier automatiquement les systèmes de glissement activés, (2) d’estimer l’émissivité de la surface permettant ainsi une détermination des champs thermiques avec une précision de 30 mK, (3) de projeter les champs bruts expérimentaux sur la microstructure et (4) de permettre la modélisation du polycristal et de ses conditions aux limites thermomécaniques réelles dans un cadre de plasticité cristalline dans le code EF Abaqus. Il a notamment été montré que les variations de température fournissent une estimation précise et aisée de la limite d'élasticité macroscopique ainsi que la détermination de la contrainte de cisaillement critique à l'échelle granulaire. En outre, les mesures cinématiques ont permis l'identification des systèmes de glissement activés. Des bilans énergétiques expérimentaux et numériques ont été réalisés et une grande influence de l'hétérogénéité polycristalline sur les mécanismes de stockage d’énergie a été soulignée. Les méthodes proposées contribueront à améliorer les critères d’endommagement basés sur un cadre dissipatif / Strain localization and damage criteria of materials and structures are commonly based on a dissipative framework and this work investigates the thermomechanical couplings accompanying the deformation micromechanisms. It is partly based on experimental data obtained previously in the laboratory by Bodelot for a A316L austenitic stainless steel polycrystal. This work takes profit of a multi-technique approach combining, in particular, in-situ kinematic and thermal fields measurements as well as Orientation Imaging Microscopy, profilometry and surface micrography. Different tools have been developed (1) to automatically identify the activated slip systems directly from the surface micrography, (2) to approach the surface emissivity field allowing an accurate determination of the thermal fields with a 30 mK precision, (3) to project raw experimental fields on the microstructure and (4) to allow the modeling of the polycrystal aggregate and its real thermomechanical boundary conditions by using a crystal plasticity framework within the Abaqus FE code. It has notably been shown that the temperature variations provides an easy and accurate estimation of the macroscopic yield stress at the specimen scale as well as the determination of the Critical Resolved Shear Stress at the intragranular scale. In addition, the local kinematic measurements allow the in-situ identification of the activated slip systems. Experimental and numerical energy balances have been conducted and a great influence of the polycrystalline heterogeneity on the energy storage mechanism has been underlined. The proposed methods would help improving physical based dissipative criteria for damage analysis

Les polymères semi-cristallins à chaînes semi-rigides, bien qu’abondamment utilisés dans la vie quotidienne, représentent des systèmes complexes qui ne sont pas encore parfaitement compris. Parmi les nombreux domaines de recherche sur cette famille de polymères, l’étude de la morphologie semi-cristalline et des processus de cristallisation et de fusion de ceux-ci restent des sujets très importants. L’investigation de la morphologie semi-cristalline est rendue difficile car elle présente une structure hiérarchique composée de plusieurs niveaux d’organisation, dont le plus petit est observable à une échelle très réduite de quelques nanomètres. De plus, les aspects liés à la cinétique des processus de cristallisation et de fusion n’ont pas toujours permis de bien les mettre en évidences, les rendant ainsi par très bien compris. Cependant, les nouvelles avancées technologiques dans le domaine de la physique expérimentales ont beaucoup profité à la science des polymères. <p>Dans ce travail, une contribution originale est apportée à cette étude, et cela en combinant diverses techniques expérimentales permettant des mesures calorifiques et structurales en températures et temps réels. L’intérêt c’est porté sur les polymères linéaires aromatiques tels que le polyéthylènes teréphthalate, PET, et le polytriméthylène téréphthalate, PTT, caractérisés par une température de transition vitreuse supérieure à l’ambiante ( Tg > 50°) et une température de fusion élevée (Tm>220°C), offrant ainsi une assez large gamme de température de cristallisation (Tm-Tg). L’étude de la structure semi-cristalline du PET à l’échelle du nanomètre et de la relaxation des phases amorphes présentes dans sa structure est facilitée par l’utilisation d’un diluant amorphe tel que le polyétherimide (PEI), qui forme un mélange miscible avec le PET. <p>L’utilisation de microscopie de force atomique AFM à haute température a permis d’observer la cristallisation isotherme de PET en temps réel et de décrire ainsi la cristallisation secondaire comme un processus d'épaississement des piles lamellaires. De plus, l’analyse de la structure semi-cristalline du PET et du PTT, dans l’espace direct, sont en faveur d’un modèle structural homogène, où l’épaisseur lamellaire moyenne est légèrement inférieure à l’épaisseur moyenne des régions amorphes interlamellaires. Ces résultats ont permis, d’une part, d’apporter une meilleure interprétation aux données obtenues par diffusion des rayons X aux petits angles (SAXS), et d’autre part, d’ interpréter le comportement de fusion multiple caractéristique des polymères semi-cristallin à chaînes semi-rigides par le seul processus de fusion-recristallisation. Dans l’étude investiguée sur les mélanges PET/PEI et sur le PTT pur, on montre que la cinétique d’un tel processus est particulièrement rapide comparée à la cristallisation. De plus, les observations par AFM et par microscopie optique de même que les mesures SAXS en temps réel ont montré la simultanéité et la compétition existant entre la fusion des cristaux et leur réorganisation durant la chauffe. Par ailleurs, la relaxation des régions amorphes interlamellaires, souvent considérées comme rigides, a pu être mise en évidence par les mesures AFM et SAXS réalisées à haute température sur des échantillons de PET/PEI semi-cristallins.<p> / Doctorat en sciences, Spécialisation physique / info:eu-repo/semantics/nonPublished

Cette thèse s’inscrit dans le cadre du développement de cibles d’irradiation faiblement enrichi en ²³⁵U pour la production du ⁹⁹Mo, radionucléide père du ⁹⁹mTc employé en imagerie médicale. La cible d’irradiation est une plaque fine en aluminium, dont l’âme fissile est constituée d’une dispersion de particules uranifères dans une matrice d’aluminium. Nos travaux plus spécifiquement ont mené à proposer une âme fissile alternative à celle actuellement employée. Pour évaluer les effets de l’affinité chimique, une approche thermodynamique par détermination des relations de phases a été considérée pour cinq systèmes ternaires de références. Les travaux expérimentaux ont conduit à la détermination de sections isothermes pour les systèmes U-Al-X avec X= Ti, Zr, Nb, Ga et Ge, pour deux températures, une basse et une haute températures représentatives des interactions avec l’uranium dans sa forme allotropique orthorhombique (αU) et cubique (gU) respectivement. Les systèmes ternaires U‑Nb-Al et U-Al-Ga, ont fait l’objet d’une optimisation thermodynamique par méthode CALPHAD. Des caractérisations supplémentaires ont été menées sur les phases intermédiaires afin de déterminer leurs propriétés physico-chimiques. Ces examens ont concerné leurs propriétés thermodynamiques (réaction de formation et température et pour certaines enthalpie de formation), structurales et également l’investigation de leurs propriétés électroniques. Cette thèse s’est également intéressée à l’étude des germaniures d’uranium ternaires, U₃TGe₅, en particulier à la recherche de nouvelles phases isotypes et à la caractérisation de leurs propriétés électroniques. Neuf nouveaux composés ont été identifiés pour les métaux T = V, Cr, Zr, Mn, Nb, Mo, Hf, Ta et W avec un arrangement structural similaire à l’antitype Hf₅CuSn₃ et des comportements variés et complexes, tels des fluctuations de spin, de l’ordre antiferromagnétique et ferromagnétique, illustrant le rôle prépondérant du métal de transition dans ces effets électroniques. / This thesis is in the framework of the development of low ²³⁵U enriched irradiation targets for the ⁹⁹Mo production, the mother isotope of ⁹⁹mTc, which is the main radioactive tracers used in nuclear medical imaging. The aim of this work is to identify a new material with a higher uranium density. To fulfil this objective, the determination of the phase relations has been considered for five ternary systems. The experimental work was the determination of the isothermal sections of the U-Al-X with X = Ti, Zr, Nb, Ga and Ge for two temperatures, for representative interactions with U in its orthorhombic form (αU) and cubic form (gU) respectively. The U-Nb-Al and U-Al-Ga ternary system were thermodynamically assessed by CALPHAD assessment. Subsequent characterizations have been carried out on the intermediate phases to determine their physical properties. These studies comprise their thermodynamic features (reaction of formation, including the reaction temperature and for some their enthalpy of formation), structural properties (by means of X-ray and electron diffractions) and their electronic properties, magnetic, and transport (electrical and thermal). This Ph-D thesis was extended to the study of ternary uranium germanides with the general formula U₃TGe₅ by seeking for new isostructural compounds and to investigate their electronic properties. Nine new compounds have been identified with the transition metal, T = V, Cr, Mn, Zr, Nb, Mo, Hf, Ta and W with an anti-Hf₅CuSn₃ structural type and various and complex behaviors, such as spin fluctuators, antiferromagnetic and ferromagnetic orders, emphasizing the predominant influence of the transition metal in these electronic phenomena.

Standard crystalline silicon photovoltaic (PV) modules are designed to continuously convert solar energy into electricity for 25 years. However, the continual generation of electricity by the PV modules throughout their designed service life has been a concern. The key challenge has been the untimely fatigue failure of solder interconnections of solar cells in the modules due to accelerated thermo-mechanical degradation. The goal of this research is to provide adequate information for proper design of solar cell solder joint against fatigue failure through the study of cyclic thermo-mechanical stresses and strains in the joint. This is carried-out through finite element analysis (FEA) using ANSYS software to develop the solar cell assembly geometric models followed by simulations. Appropriate material constitutive model for solder alloy is employed to predict number of cycles to failure of solder joint, hence predicting its fatigue life. The results obtained from this study indicate that intermetallic compound thickness (TIMC); solder joint thickness (TSJ) and width (WSJ) have significant impacts on fatigue life of solder joint. The impacts of TIMC and TSJ are such that as the thicknesses increases solder joint fatigue life decreases. Conversely, as solder joint width (WSJ) increases, fatigue life increases. Furthermore, optimization of the joint is carried-out towards thermo-mechanical reliability improvement. Analysis of results shows the design with optimal parameter setting to be: TIMC -2.5μm, TSJ -20μm and WSJ -1000μm. In addition, the optimized model has 16,264 cycles to failure which is 18.82% more than the expected 13,688 cycles to failure of a PV module designed to last for 25 years.

Indentation hardness, H, has been widely used to characterize the mechanical properties of materials for more than a century because of the following advantages of this technique; (1) it requires small sample and (2) the test is non destructive in nature. Recent technological advances helped in the development of instrumented indentation machines which can record the load, P, vs. displacement, h, data continuously during indentation with excellent load and displacement resolutions. From these, H and the elastic modulus, E, of the indented material can be obtained on the basis of the ‘contact area’ of the indentation at the maximum load. The estimation of true contact area becomes difficult during ‘pile-up’ and ‘sink-in’, commonly observed phenomena while indentation of a low and high strain hardened materials. In order for the better understanding of these phenomena it is important to understand the plastic flow distribution under indenters. It is also important for the prediction of elastic-plastic properties from the P-h data. Recently, there have been considerable theoretical and simulation efforts on this front with a combination of dimensional analysis and finite element simulations. One of the important input parameter for the dimensional analysis is the ‘representative strain’ under the indenter, which is a strong function of the indenter geometry. However there is no comprehensive understanding of the representative strain under the indenter despite several studies till date. One objective of the present thesis is to conduct an experimental analysis of the plastic flow during the sharp indentation. The plastic zone size and shape under conical indenters of different apex angles in a pure and annealed copper were examined by employing the subsurface indentation technique to generate the hardness map. From these isostrain contours are constructed joining the data having similar strain values. The following are the key observations. (1) The plastic strain contours are elliptical in nature, spreading more along the direction of the indenter axis than the lateral direction. (2) The magnitude of the plastic strain in the contact region decreases with increasing the indenter angle. (3) The strain decay in the indentation direction follow a power-law relation with the distance. The estimated representative strains under the indenters, computed as the volume average strain within the elastic-plastic boundary, decreases with increasing indenter angle. We also performed finite element simulations to generate plastic flow distribution under the indenter geometries and compared with the experimental results. The results suggest that the experimental and computed average strains match well. However, the plastic strain contours do not, suggesting that further detailed understanding of the elasto-plastic deformation underneath the sharp indenter is essential before reliable estimates of plastic properties from the P-h curves can be made routinely. The second objective of this thesis is to understand plastic flow in amorphous alloys. It is now well established that plastic deformation in metallic glasses is pressure sensitive, owing to the fundamentally different mechanisms vis-à-vis the dislocation mediated plastic flow in crystalline metals alloys. Early work has shown that the pressure sensitivity of amorphous alloys gets reflected as high constraint factor, C (hardness to yield stress ratio), which sometimes exceed 3.0. In this thesis, we study the temperature dependence of pressure sensitive plastic flow in bulk metallic glasses (BMGs) using C as the proxy for the pressure sensitivity. Experiments on three different BMGs show that C increases with temperature hence the pressure sensitivity. In addition we have carried out finite element simulations to generate P-h curves for different levels of pressure sensitivities and match them with the experimental curves that are obtained at different temperatures. Simulations predict that higher pressure sensitivity index values are required to match the experimental curves at high temperatures confirming that the pressure sensitivity increases with increasing temperature. The fundamental mechanisms responsible for the increase in pressure sensitivity are discussed in detail. Finally we pose a question, is the increase in pressure sensitivity with temperature is common to other amorphous materials such as strong amorphous polymers? In order to answer this question we have chosen PMMA, a strong amorphous polymer. In this study also we have taken C as a proxy to index the pressure sensitivity. Indentation stress-strain curves are constructed at different temperature using spherical indentation experiments. The C values corresponding to different temperatures are determined and plotted as a function of temperature. It is found that C increases with temperature implying that the pressure sensitivity of amorphous polymers also increases with temperature. The micro-mechanisms responsible for the increase in pressure sensitivity are sought.