Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In the present dissertation, the synthesis and characterization of cellulose acetate membranes as well as cellulose acetate and polystyrene blends, were studied. Recycled materials were used to produce the blends. Cellulose acetate (CA) was produced from sugarcane bagasse, and waste plastic cups were used as polystyrene (PS) source. Blends, produced with different CA/PS ratios, were characterized regarding the miscibility of their components. The techniques utilized for membrane characterization were Fourier Transform Infrared Spectrometry (FTIR), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and measurements of water diffusion through the membranes. The results confirmed the existence of miscibility microregions in the blends and indicated a region of transition when 30% PS was used, indicating a limit for a possible phase inversion between the matrix and the disperse phase. The membranes were also characterized regarding their properties of water flux, PEG rejection (utilizing an aqueous solution 1% w/v of polyethylene glycol, PEG, 45 kDa and 80 kDa) and ion diffusion by dialysis. The experiment of ion diffusion by dialysis showed that the coefficients of ion diffusion of both the pure CA and the CA/PS blends were comparable to previously reported values for commercial cellulose triacetate membrane. These results showed that the membrane produced from recycled materials, sugarcane bagasse and polystyrene cups, behaves likewise the commercial material. Regarding permeation driven by difference of pressure, 12% w/w membrane showed the best performance and rejected 27% PEG 80 kDa. These preliminary results showed that this membrane should be better evaluated in the range of application comprehending ultrafiltration or microfiltration processes. / Nesta dissertação estudou-se a síntese e caracterização de membranas de acetato de celulose e blendas de acetato de celulose com poliestireno. Foram utilizados materiais reciclados, sendo o acetato de celulose (AC) obtido pela reciclagem do bagaço de cana-de-açúcar, e o poliestireno (PS) de copos plásticos descartados. As blendas, produzidas com diferentes proporções de AC/PS, foram caracterizadas quanto a miscibilidade dos seus componentes. As técnicas utilizadas foram a Espectrometria de Infravermelho com Transformada de Fourrier (FTIR), Calorimetria Diferencial Exploratória (DSC), Análise Termogravimétrica (TGA), Microscopia Eletrônica de Varredura (MEV) e medidas de difusão de água através das membranas. Os resultados confirmaram a existência de microrregiões de miscibilidade nas blendas, e também evidenciaram uma região de transição na proporção de 30% de PS, indicando um limite para uma possível inversão de fases entre a matriz e a fase dispersa. As membranas também foram caracterizadas por fluxo de água, rejeição ao PEG (de diferentes massas molares) e difusão de íons por diálise, visando apontá-las para possíveis processos de separação. Os experimentos de difusão de íons por diálise mostraram que o coeficiente de difusão de íons, tanto das membranas de AC puro quanto das blendas AC/PS, foram comparáveis ao valor encontrado na literatura para uma membrana de triacetato de celulose comercial. Estes resultados demonstram que as membranas produzidas a partir de materiais reciclados, bagaço de cana-deaçúcar e copos de poliestireno, apresentaram performance comparável àquela produzida de um material comercial. Com relação ao experimento por diferença de pressão, a membrana de AC 12% mostrou a melhor performance e rejeitou 27 % do PEG 80 kDa. Estes resultados preliminares mostram que esta membrana pode ser indicada para uma melhor avaliação em uma faixa de aplicação que compreende os processos de ultrafiltração e microfiltração. / Mestre em Química

Submitted by Jean Medeiros (jeanletras@uepb.edu.br) on 2018-05-18T12:53:12Z No. of bitstreams: 1 PDF - Fábio Junior Mota dos Santos.pdf: 16470271 bytes, checksum: 931fe4e9cb3a582ced25e4d4c19d1ffc (MD5) / Made available in DSpace on 2018-05-18T12:53:12Z (GMT). No. of bitstreams: 1 PDF - Fábio Junior Mota dos Santos.pdf: 16470271 bytes, checksum: 931fe4e9cb3a582ced25e4d4c19d1ffc (MD5) Previous issue date: 2017-03-31 / There are countless researches related to the treatment of waste water because they contain large amounts of recalcitrant chemicals, such as p-Nitrophenol widely used in the industry in dyeing leather. Because it is a very toxic substance even at low concentrations, its total removal and / or transformation into other less polluting substances becomes an urgent environmental issue. Gold nanoparticles because they have great catalytic potential besides being non-toxic can somehow contribute to the minimization of the environmental effects caused by nitrophenols. Reactions using homogeneous catalysts are not very feasible in some cases, they present great difficulty during the separation of the catalysts from the rest of the reaction medium. In this context, this work aimed at the development of a catalyst based on gold nanoparticles impregnated in polystyrene foams an industrial waste, using thermally induced phase separation as the method of obtaining the same. It is then tested for catalytic reduction of p-Nitrophenol. The gold nanoparticles of different diameters were obtained using different synthesis conditions and characterized by spectrophotometry in the region of the visible for the size measurement, whereas for the already impregnated foams the characterization techniques used were the scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric (TG) analysis and thermogravimetric analysis (DTG). The catalyst was tested using as a model reaction the reduction of p-Nitrophenol to p-Aminophenol, the whole process was accompanied by UV-vis and what is concluded is a variation in the reaction velocities as a function of the variation of the particle size present in the foam and / or their concentrations therein. / Já são inúmeras as pesquisas relacionadas ao tratamento de águas residuais pelo fato de as mesmas conterem grandes quantidades de substancias químicas recalcitrantes, a exemplo do p-Nitrofenol muito utilizado na indústria no tingimento de couro. Por se tratar de uma sustância muito tóxica mesmo em baixas concentrações sua total remoção e/ou transformação em outras menos poluentes, torna-se uma questão ambiental urgente. As nanopartículas de ouro por apresentarem grande potencial catalítico além de não serem tóxicas, podem de alguma forma contribuir para a minimização dos efeitos agressivos ao ambiente causados por nitrofenóis. Reações que utilizam catalisadores homogêneos são pouco viáveis em alguns casos, apresentam grande dificuldade durante a separação do catalisados do restante do meio reacional. Nesse contexto esse trabalho objetivou o desenvolvimento de um catalisador a base de nanopartículas de ouro impregnadas em espumas de poliestireno um rejeito industrial, utilizando como método de obtenção para o mesmo a separação de fases induzida termicamente. Para então testa-lo na redução catalítica do p-Nitrofenol. As nanopartículas de ouro de diferentes diâmetros foram obtidas utilizando-se diferentes condições de síntese e caracterizadas através da espectrofotometria na região do visível para a aferição do tamanho, enquanto que para as espumas já impregnadas as técnicas de caracterização utilizadas foram a microscopia eletrônica de varredura (MEV), difração de raio-X (DRX), analise termogravimétrica (TG) a derivada da analise termogravimétrica (DTG). O catalisador foi testado utilizando como reação modelo a redução do p-Nitrofenol a p-Aminofenol, todo o processo foi acompanhado por UV-vis e o que se conclui é uma variação nas velocidades das reações em função da variação do tamanho de partículas presente na espuma ou/e de suas concentrações na mesma.

O objetivo do trabalho foi sintetizar e caracterizar nanopartículas de poliestireno e polimetacrilato de metila com morfologia núcleo-casca obtidas através da polimerização em emulsão sem emulsificante em dois estágios e através da fotopolimerização. Nos experimentos avaliou-se a influência de diferentes condições operacionais baseadas em fatores cinéticos sobre os dois estágios da polimerização. As condições avaliadas para o primeiro estágio de preparação de núcleos foram: a temperatura do processo, a concentração de iniciador e de monômero, e o efeito de agentes modificadores de superfície (sal, co-monômero e reticulante). Para o segundo estágio de formação da casca as condições avaliadas foram: a concentração e o regime de alimentação de monômero. Os resultados experimentais mostraram que uma relação de co-monômero e reticulante é a melhor alternativa para preparar núcleos estáveis e de diâmetros pequenos. Assim, o revestimento uniforme dos núcleos é obtido no segundo estágio e com isso a morfologia núcleo-casca em equilíbrio é alcançada. Dois sistemas experimentais (reator convencional e reator fotoquímico) foram propostos e avaliados na sua eficiência para obter partículas com este tipo de morfologia no segundo estágio (formação do revestimento). As diversas técnicas de caracterização indicaram a formação de morfologia núcleo-casca na maioria dos casos estudados para os dois sistemas propostos. Por sua vez, as técnicas espectroscópicas (NIR e Raman) permitiram o monitoramento do processo em tempo real e a elaboração de modelos de calibração que correlacionaram o crescimento do tamanho da partícula núcleo. Da mesma forma, os fatores termodinâmicos foram estudados para predizer a morfologia final esperada nos sistemas. Os resultados, experimental e predito são comparados e discutidos em termos de aspectos chave envolvidos no controle da morfologia da partícula. / This work aimed at studying the synthesis and characterization of core-shell nanoparticles of polystyrene and polymethylmethacrylate obtained in a two-stage emulsifier-free emulsion polymerization and photopolymerization. The influence of different operational conditions based on kinetic factors was experimentally evaluated. In the first stage (seed preparation) the process temperature, initiator and monomer concentrations and the effect of surface-modifier agents (acids, salts, co-monomers and crosslinker) were investigated; similarly in the second stage, the concentration and feeding regime of monomer were evaluated with respect to the shell formation. Experimental results showed that both, crosslinker and co-monomer are the best alternative to achieve a stable seed with small diameter; hence, with this core, uniform coating is obtained in the second stage and core-shell morphology is reached. In order to evaluate the efficiency of the preparation of core-shell particles, two experimental systems (conventional and photochemical reactor) were studied. Different characterization techniques indicated that in most of the cases studied particles with the desired core-shell morphology were formed. The use of spectroscopic techniques NIR and Raman were tested for the real-time monitoring of the process using adequate calibration models developed to correlate the average size of the growing core particle with the spectra. In the same way, thermodynamic factors were used to predict the expected final morphology of the particles. Experimental and predicted results were compared and discussed in terms of the key aspects involved in the control of the particle morphology.

Orientadores: Flavio Garcia, Eduardo Granado Monteiro da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-10T05:04:16Z (GMT). No. of bitstreams: 1 Soares_MarcioMedeiros_M.pdf: 20040711 bytes, checksum: 307f0dbee3ef2d92b25427c28d39c7d6 (MD5) Previous issue date: 2008 / Resumo: Neste trabalho fizemos um estudo sistemático de filmes compostos por multicamadas Co/Pd depositados sobre arranjos auto-organizados de esferas de látex submicrométricas (50 ¿ 1000 nm). O filme depositado sobre a esfera (não-magnética) forma uma calota magnética com espessura variável. As espessuras de Co e Pd foram escolhidas de modo a obter duas classes de multicamadas, uma com anisotropia intrínseca perpendicular e outra com anisotropia intrínseca planar, quando depositadas sobre um substrato plano. Os arranjos de calotas com anisotropia intrínseca perpendicular que produzimos têm um comportamento magnético que reproduz resultados publicados recentemente na literatura. Para os sistemas com anisotropia intrínseca planar a microestrutura magnética é profundamente dependente da forma tridimensional da calota, assim como do seu tamanho. A investigação destas calotas envolveu caracterizações magnéticas por efeito Hall extraordinário, efeito Kerr magneto-ótico e SQUID, análise estrutural por microscopia eletrônica de transmissão (TEM) e sondagem da configuração da magnetização por microscopia de força magnética (MFM). Para esferas menores (diâmetros de 50 e 100 nm), as imagens de TEM mostram que as calotas segmentam-se em nanopilares orientados radialmente. Em concordância com as caracterizações magnéticas, propomos que a segmentação em pilares induz uma anisotropia efetiva radial nessas calotas menores. Nas calotas maiores (500 e 1000 nm) estudamos a influência do gradiente de espessura, medido por TEM, sobre a anisotropia efetiva ao longo da esfera. Nestas calotas as multicamadas são contínuas e, correlacionando caracterizações magnéticas, imagens de TEM, medidas de MFM e simulações micromagnéticas, chegamos à conclusão de que a magnetização forma um vórtice em seu topo, influenciada pela forma tridimensional da calota. O núcleo dos vórtices que observamos é razoavelmente maior do que aqueles mostrados na literatura para vórtices em discos, indicando que tal sistema de calotas pode ser promissor para aplicações em mídias de gravação magnética / Abstract: In this work we have performed a systematic study on Co/Pd multilayers deposited over self-assembled polystyrene nanospheres (with diameter ranging from 50 to 1000 nm). The film deposited over the nonmagnetic nanosphere forms a magnetic cap with variable thickness. The Co and Pd layer thicknesses were chosen in order to obtain two classes of multilayers, one exhibiting intrinsic in-plane anisotropy and the other exhibiting intrinsic out-of-plane anisotropy, when deposited on flat substrates. The magnetic behavior of the caps¿ arrays with intrinsic out-of-plane anisotropy which we have produced agrees with results recently reported in the literature. The magnetic microstructure of the systems with intrinsic in-plane anisotropy is mainly influenced by three-dimensional shape and size of the caps. The study of those caps included magnetic characterization by Extraordinary Hall Effect, Magneto-Optic Kerr Effect and SQUID, structural analysis by Transmission Electron Microscopy (TEM) and magnetic configuration probing by Magnetic Force Microscopy (MFM). For the smallest spheres (50 and 100 nm in diameter) TEM images show that the cap is segmented into radial nanopillar like structures. Agreeing with our magnetic measurements, we propose that this segmentation induces an effective radial anisotropy in the smallest caps. For the largest caps (500 and 1000 nm in diameter) we have studied the influence of the thickness gradient (probed by TEM) on the effective anisotropy along de cap. In those caps the multilayers are continuous and, correlating magnetic characterizations, TEM images, MFM profiles and micromagnetic simulations, we concluded that the magnetization forms a curling structure in the top of the caps. The so formed magnetic vortex is strongly influenced by the cap¿s shape. We observed that the magnetic vortex core is considerably larger than the ones shown in the literature for vortex in planar discs, indicating that this cap system may be promising for applications in magnetic recording medias / Mestrado / Materiais Magneticos e Propriedades Magneticas / Mestre em Física

O bagaço de cana-de-açúcar é um abundante coproduto obtido a partir da produção convencional de etanol. No entanto, o bagaço vem se mostrando como uma importante fonte para a produção de etanol de segunda geração. No primeiro capítulo da tese é apresentado um estudo referente à distribuição espacial dos compostos na matriz de bagaço de cana-de-açúcar. A investigação foi realizada utilizando microscopia de fluorescência confocal e espectroscopia por excitação com um e dois fótons. Imagens de autofluorescência em combinação com as medidas de fluorescência e tempos de vida forneceram uma gama de informações necessárias para a caracterização de amostras de bagaço. Além disso, a técnica permite o acompanhamento de processos relacionados com a remoção de lignina. A nanocelulose cristalina (NCC) é um material promissor devido as suas propriedades intrínsecas, tais como seu formato alongado, medindo de 1 a 100 nm de diâmetro e seu comprimento variando de algumas dezenas a centenas de nanômetros. No capítulo 2, a nanocelulose cristalina foi obtida através da hidrólise da celulose cristalina (de Avicel®) com ácido sulfúrico. Em seguida, o material foi caracterizado por técnicas de microscopia SEM e TEM, confirmando a morfologia em forma de haste e a estrutura de tamanho nanométrico. A microscopia de campo largo convencional foi utilizada como ferramenta na caracterização da NCC dispersa em soluções poliméricas de PVA e PVP. A última parte do capítulo 2 descreve a caracterização de estruturas de NCC usando a microscopia de super-resolução de fluorescência STED (depleção de emissão estimulada). As imagens mostraram uma resolução de até 50 nm, permitindo a comparação com resultados de TEM e AFM. No capítulo 3, a nanocelulose cristalina foi covalentemente marcada com o corante ATTO-532, através da chamada reação \"click\". As propriedades relacionadas com o coeficiente de difusão da NCC foram determinadas por espectroscopia de correlação de fluorescência (FCS). Em uma etapa posterior, a NCC foi colocada em diferentes soluções do polímero PEG, contendo quantidades diferentes. As propriedades dinâmicas foram analisadas por métodos de FCS e WFM. O uso de técnicas de espectroscopia e microscopia revelou detalhes relacionados à heterogeneidade das dispersões de NCC, as quais estão relacionadas com as propriedades hidrofílicas e hidrofóbicas das soluções poliméricas. / The sugarcane bagasse is an abundant co-product obtained from the conventional production of ethanol. However, sugarcane bagasse has been proving to be an important source to the production of second-generation ethanol. In the first chapter, the spatial distribution of compounds in the sugarcane bagasse matrix was investigated by confocal fluorescence microscopy and spectroscopy with one and two-photon excitation. Autofluorescence images in combination to spectral emission and lifetime measurements provided a tool for the characterization of natural bagasse samples. Moreover, the technique allows the following of processes related to the lignin removal. Nanocrystalline cellulose (NCC) is a promisor material because of its properties, such as rod-shape with 1-100 nm in diameter, and tens to hundreds of nanometres in length. In the Chapter 2, NCC was obtained via sulphuric acid hydrolysis from Avicel®. Afterwards, the material was characterized by classic electronic microscopy SEM and TEM, confirming the rod-shaped morphology and the nano-sized structure. Conventional wide field microscopy was used as fluorescence microscopy tool in the characterization of NCC, when dispersed in polymeric solutions of PVA and PVP. The last part of the chapter 2 describes the characterization of NCC structures by using the super-resolution fluorescence microscopy STED (Stimulated Emission Depletion). The STED images showed a resolution down to 50 nm, allowing the comparison with TEM and AFM microscopy results. In the Chapter 3, the NCC was covalently labelled, by a click-chemistry reaction, with the ATTO-532 dye. Properties related to diffusion coefficient of NCC were determined by Fluorescence Correlation Spectroscopy (FCS) method. Afterwards, NCC was placed into a solution of PEG, containing different amounts polymer. The dynamic properties were evaluated by FCS and WFM methods. The use of spectroscopy and microscopy imaging techniques revealed heterogeneity details of NCC dispersions, which are related to the hydrophilic and hydrophobic properties of the polymer solution. A better understanding of polymer systems is achieved by investigation of diffusion properties, that allows the comprehension of rheological parameters, and, consequently, in polymer processing and assembly of plastics, films, and fibres. In the Chapter 4 is presented a study where fluorescence correlation spectroscopy (FCS) and wide-field fluorescence microscopy (WFM) were used to follow changes in the diffusion coefficients of growing polymer chains, during the controlled radical polymerization process. Linear and star-shaped polystyrene were grown via nitroxide-mediated polymerization (NMP) from alkoxyamine-based initiators containing a highly fluorescent perylene diimide moiety. This study demonstrates that direct investigation of heterogeneity emerging during a controlled radical polymerization process by means of fluorescence of single-molecule chain initiator allows unravelling information related to the diffusion processes of the growing polymer chain.

O presente projeto tem como objetivo contribuir para o desenvolvimento de dispositivos para monitoração de pressão dinâmica do ar. Para isso, foram produzidos filmes sensíveis a pressão baseados na detecção de concentração de oxigênio por meio de processos de emissão fotoluminescente das moléculas de Azul de Metileno (MB) e Platina Octaetilporfirina (PtOEP). Nesse sentido, foi estudado o comportamento da emissão fotoluminescente dessas moléculas em interação com o gás de oxigênio. A concentração de oxigênio (do ar) sobre superfície sensível depende da pressão dinâmica de superfície. Desta forma, monitorando a fotoluminescência dos dispositivos submetidos a diferentes concentrações de oxigênio, pode-se determinar uma relação entre a pressão pontual da superfície analisada e a intensidade de emissão fotoluminescente do filme. Os dispositivos de monitoração de pressão dinâmica são constituídos de um filme de estado sólido contendo as moléculas sensíveis. Foram utilizados como substratos hospedeiros para o Azul de Metileno e para a Octaetilporfirina de Platina, os filmes de silício poroso oxidado e Poliestireno, respectivamente. É proposto um arranjo experimental que utiliza um fluorímetro para caracterizar as amostras produzidas e uma câmara de fluxo de gases. Os dispositivos apresentaram elevada sensibilidade e evidenciaram o potencial para desenvolvimento e integração de sensores baseados no silício poroso à microeletrônica. / This project aims to contribute to the development of devices for monitoring dynamic pressure of the air. In this sense, films were produced based on pressure-sensitive detection of oxygen concentration through processes of photoluminescence emission from the molecules of methylene blue (MB) and platinum octaethylporphyrin (PtOEP). Accordingly, it was studied the behavior of the photoluminescence emission of these molecules in interaction with the oxygen gas. The concentration of oxygen (of the air composition) on the sensitive surface depends on the surface dynamic pressure. Thus, monitoring the photoluminescence of the devices under different oxygen concentrations, it can be determined a relationship between the punctual pressure of the tested surface and the photoluminescence emission intensity of the film. The devices for monitoring dynamic pressure are made of a solid state film containing the sensitive molecules. Oxidized porous silicon and polystyrene films were used as hosts for the Methylene Blue and for the Platinum Octaethylporphyrin, respectively. It was proposed an experimental setup that uses a spectrofluorophotometer and a gas flow chamber to characterize the produced samples. The devices showed high sensitivity and potential for development and integration of the sensors based on porous silicon for microelectronics.

L’objectif de ce projet est d’étudier l’interaction de nanoparticules polymères avec les membranes, soit directement sur des cellules entières ou grâce à des modèles membranaires biomimétiques, dans l’optique de valider leur utilisation dans le cadre d’applications biologiques. Des nanoparticules (NPs) polymères cœur/enveloppe avec un diamètre inférieur à 100 nm ont été synthétisés. Cette taille a été choisie afin de leur permettre de pénétrer à travers les membranes plasmiques. Des nanoparticules ayant la même composition chimique mais avec un diamètre hydrodynamique supérieur, de l’ordre de 250 nm, ont été également préparées afin de mettre en évidence l’effet de la taille des particules sur le processus d’internalisation cellulaire. Dans cette thèse, une méthode innovante de synthèse monotope a été développée pour obtenir des NPs coeur-enveloppe, compatibles en milieu aqueux et présentant à leur surface des résidus iniferter. Le coeur est composé de polystyrène avec une taille d’environ 30 nm. Un large éventail de fonctionnalités peut être greffé sur la surface du coeur par polymérisation radicalaire contrôlée en faisant varier différents types de monomères. L’épaisseur de l’enveloppe peut être ajustée en fonction de la concentration en monomère et du temps de polymérisation. Les nanoparticules synthétisées ont été caractérisées par diffusion dynamique de la lumière, par spectroscopie infrarouge à transformée de Fourier, par analyse micro-élémentaire et par microcopie à transmission électronique. Les interactions des NPs à coeur polystyrène et avec des enveloppes de charge neutre et négative ont été étudiées avec des cellules kératinocytes épidermiques humaines néonatales (NHEK), des fibroblastes primaires humains et les cellules HACaT de kératinocytes humains. Les études de cytotoxicité réalisées en utilisant un marquage à l’iodure de propidium et un test à la lactate déshydrogénase n’ont relevé aucune toxicité sur les lignées testées. Cependant, le suivi de la prolifération cellulaire par impédance électrique de substrats cellulaires a indiqué que les nanoparticules anioniques induisent une forte diminution de la prolifération des kératinocytes. L’internalisation cellulaire des NPs a été confirmée par microscopie confocale qui n’indique pas leur colocalisation avec les endosomes précoces, les lysosomes et l’actine. De plus, les données obtenues par triage cellulaire par cytofluorométrie soutiennent qu’un mécanisme énergétiquement-dépendant est mis en œuvre pour l’internalisation des NP neutres, ce qui semble être moins le cas pour les nanoparticules négatives. Les membranes biomimétiques ont été employées afin d’étudier les spécificités des interactions entre nanoparticules et lipides dans des conditions contrôlées. L’étude sur des modèles de vésicules géantes couplée à de la spectroscopie de fluorescence a révélé que les nanoparticules coeur/enveloppe sont capables d’interagir profondément dans la région hydrophobe de la membrane, mais uniquement quand la bicouche lipide est en phase fluide désordonnée. Le mode de pénétration des NPs au travers de la bicouche des vésicules semblent engendrer la formation de pores. Un effet plus prononcé de rigidification de la bicouche a pu être observé lors de l’interaction de nanoparticules chargées négativement avec les bicouches de phosphatidycholines. Cet effet pourrait être attribué à un changement de l’orientation des têtes phosphocholines du à des interactions électrostatiques. En conclusion, les nanoparticules polymère que nous avons synthétisées apparaissent être des outils polyvalents pour les études d’interaction cellulaire et d’imagerie. Ces nanomatériaux peuvent être éventuellement être employés pour la délivrance de médicaments en incorporant les molécules actives dans une enveloppe polymère thermosensible par exemple. / This project’s aim was to study polymeric nanoparticle-membrane interactions using both live cells and biomimetic models with the idea to validate such nanoparticles for use in bio-applications. Core-shell polymeric nanoparticles below 100 nm, as this small size is capable of penetrating plasma membranes, were synthesised. Nanoparticles (NPs) with the same chemical composition but with hydrodynamic diameters of ~250 nm, were also prepared in an effort to highlight any effect of NP size on cell internalisation. In this thesis, an innovative method is presented for the synthesis of water-compatible, iniferter-bound polystyrene core shell NPs (~30 nm) using a one-pot synthetic method. A plethora of functionalities could be added to the nanoparticles via shell grafting from the surface of the polystyrene core in the presence of additional monomers via controlled living radical polymerisation. Shell thickness could be tuned as a function of monomer’s concentration and polymerisation time. The nanoparticles were fully characterised by dynamic light scattering, Fourier transform infra-red spectroscopy, microelemental analysis and transmission electron microscopy. Further, the interactions of polystyrene core NPs possessing neutral and anionic shells were investigated using neonatal human epidermal keratinocytes (NHEK), human primary fibroblasts and HaCaT cells. Cytotoxicity studies performed using propidium iodide and lactate dehydrogenase indicated no evidence of cytotoxicity in either cell line. However, cell proliferation monitored by electric cell substrate impedance sensing (ECIS) protocols indicated that anionic nanoparticles induced a dramatic decrease in cell proliferation in keratinocytes. The cellular internalisation of NPs was confirmed by confocal microscopy and no co-localisation was found with early endosomes, lysosomes or actin. Additionally, fluorescence activated cell sorting (FACS) data support the theory that an energy-dependent mechanism is employed for neutral NP internalisation but less so for negatively charged NPs. Biomimetic membrane models were used to investigate specific nanoparticle-lipid interactions under controlled conditions. Employing giant vesicles coupled with fluorescent spectroscopy techniques revealed that core-shell nanoparticles interact deep in the hydrophobic region of bilayers only when the membrane is in the fluid phase. Their mode of entering artificial cells (i.e giant vesicles) appears to cause the formation of pores. Anionic nanoparticles interact with the choline moiety of phosphatidylcholine and confer a rigidifying effect on phosphocholine containing bilayers. Therefore we conclude that the polymeric nanoparticles that we synthesized are versatile tools for cell interaction and imaging studies. These nanomaterials could eventually be applied to drug delivery studies by incorporation of the drug in for instance a thermoresponsive polymeric shell. Furthermore, it is clear that NPs coated with anionic and neutral polymeric shells present a lower toxicity profile than previously reported cationic nanoparticles. Both nanoparticles increase the order lipid bilayer vesicles composed of POPC (the most common glycerophospholipid) in animal and plants. Anionic nanoparticles in particular exhibit a rigidifying effect on POPC lipid bilayers and their mode of entry into cells may be due to the formation of pores which was determined to not induce cell death.

Le but de cette étude était de déterminer si le partage de petites molécules dans un système d'emballage/aliment change lorsque le polymère passe d’un état vitreux à caoutchoutique. La sorption par un polystyrène amorphe vitreux est un processus très lent. L’hystérésis observée entre les cycles de sorption et de désorption du n-hexane peut être due principalement à la variation de la vitesse à laquelle le système évolue au voisinage de la Tg et à une augmentation du volume libre dans le polymère. La sorption de vapeur de n-hexane ne modifie pas l’état physique du système, alors que celle du toluène induit un passage de l’état vitreux à caoutchoutique. Toutefois, le comportement du coefficient de partage du système toluène/PS reste inchangé lors de la transition vitreuse du système. L'effet de plastification provoquée par la sorption des composés volatils a été étudié. La sorption de certains composés volatils induit un abaissement significatif de la température de transition vitreuse du polystyrène. L'effet plastifiant du n-hexane lors de sa sorption par le PS était plus forte que celle des autres composés étudiés. Les valeurs de coefficients de partage du p-xylène et de l'éthylbenzène entre un film de polystyrène et l'éthylène glycol sont plus faibles que celles du n-hexane et du toluène à 25 °C. Finalement, malgré les modifications structurales induites par la sorption, l’énergie d’activation du coefficient de partage n’est pas significativement modifiée lors de la transition vitreuse. / The aim of this work was to find out whether the partitioning behavior of small molecules in a polymer food packaging system changes as the system traverses through its glass transition. Sorption in glassy amorphous polystyrene is a very slow process. The large hysteresis between sorption-desorption cycles of n-hexane/PS was hypothesized to be mainly due to varying rate at which the glass transition temperature was reduced and increase in system’s volume. The equilibrium sorption in glassy amorphous polystyrene at 25 °C, of n-hexane vapor did not modify the state of the system, whereas that of toluene vapor modified the system’s state significantly. The partitioning behavior of toluene/PS remained unchanged across the glass transition of the system. The plasticization effect caused by sorption was studied and revealed that it modifies the glass transition of a volatile/PS mixtures quite significantly. Such information is useful in knowing state modifications of the system as long as sorption/migration occurs, and thus assisting interpretation. The plasticizing effect of n-hexane in amorphous PS was stronger than that of three other volatiles studied. The estimated partition coefficient values of p-xylene and ethylbenzene between polystyrene film and ethylene glycol were several times lower than the experimental values of n-hexane and toluene at 25 °C. Finally, glass transition or change from glassy to rubbery states and vice-versa does not significantly modify the activation energy of sorption.

On many structures there ocurred a problem of expanded polystyrene-based thermal insulation material degradation caused by high temperatures close to glazed areas. In a theoretical part of this Master’s Thesis there are the most common thermal insulation materials described, followed by a brief desciption of flat roof waterproofing materials and a thermal stress of structures. An experimental part describes a design of a methodology for evaluation of thermal resistance properties of foamed insulants in flat roofs and several experiments carried out according to the methodology.

Plasty, pronikající do životního prostředí ať už neúmyslně či záměrně, mohou být fragmentovány za vzniku částic v řádu mikrometrů (tzv. mikroplastů) a znečišťovat tak půdní systémy. Doposud vyvinuté analýzy pro stanovení mikroplastů v půdách jsou především zaměřeny na kvalitativní stanovení, nicméně i jejich provedení se zatím stále potýká s různými úskalími. Navíc, téměř všechny tyto analýzy vyžadují časově náročnou předúpravu vzorku. V této studii jsme se zaměřili na vývoj nové analytické metody pro kvantitativní stanovení mikroplastů polyvinylchloridu (PVC) a polystyrenu (PS) v půdách bez předchozí úpravy vzorku pomocí termogravimetrické analýzy spojené s hmotnostní spektrometrií (TGA-MS). Pro analýzu byly použity vzorky modelové půdy s nízkým obsahem organického uhlíku, které byly spikovány na výslednou koncentraci 0,23–7 hm% PVC či PS. Vzorky byly pyrolyzovány s teplotním krokem 5 K min–1 až na teplotu 1000 °C. Pyrolýzní plynné produkty byly následně analyzovány s využitím hmotnostního spektrometru. Získaná data byla normalizována pomocí externího standardu (šťavelan vápenatý). Limity detekce se pohybovaly v rozmezí 0,08–5,3 hm% pro PVC a 0,005–0,7 hm% pro PS v závislosti na zvoleném m/z. Limity kvantifikace pak byly 0,3–17,7 hm% pro PVC a 0,002–2,2 hm% pro PS. Výsledky dokazují, že spojení TGA-MS může být konkurující semikvantitativní metodou pro stanovení mikro-PVC a mikro-PS v půdě s nízkým obsahem organického uhlíku.