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Catalysts consisting of silver on α-Al₂O₃, α-SiC, and β-SiC supports were synthesized and tested for catalytic performance in the gas-phase direct oxidation of ethylene to ethylene oxide. For this study, which used no promoters, ethylene oxidation selectivity of SiC-supported catalysts ranged from 10 to 60% and conversion from 0-4.5%. Silicon carbide supported catalysts exhibited poor performance except for a surface-modified β-SiC-supported catalyst, which demonstrated conversion and selectivity similar to that of an α-Al₂O₃-supported catalyst. This Ag/β-SiC catalyst was further investigated with a kinetic study, and the reaction orders were found to be 0.18 with respect to ethylene and 0.34 with respect to oxygen. The kinetic results were consistent with Langmuir-Hinshelwood rate expressions developed from single-site and dual-site reaction mechanisms. Gold nanoparticles on titanium oxide and titania-silica supports are active for the formation of propylene oxide by the oxidation of propylene with hydrogen and oxygen mixtures. This study investigates the effect of cyanide treatment on gold supported on titanosilicate zeolite supports (Au/TS-1). Catalysts treated with weak solutions of sodium cyanide resulted in preferential removal of small gold particles, while catalysts treated with strong solutions resulted in dissolution of the gold and re-precipitation as gold (+1) cyanide. X-ray absorption spectroscopy demonstrated that catalysts which produce propylene oxide in the presence of hydrogen and oxygen mixtures had supported gold (+3) oxide nanoparticles of 3 nm size after synthesis, which were reduced to gold metal at reaction conditions. Samples treated with strong solutions of sodium cyanide resulted in supported gold (+1) cyanide particles of large size, 9-11 nm. These particles did not produce propylene oxide but, surprisingly, showed high selectivity toward propylene hydrogenation. Increasing gold (+1) cyanide particle size resulted in a decrease in hydrogenation activity. TS-1 and Au/TS-1 surfaces were studied with laser Raman spectroscopy. Surface fluorescence was substantially reduced with a low-temperature ozone treatment, allowing observation of titanosilicate framework bands. Hydrocarbon vibrations are observed for TS-1 and Au/TS-1 under propylene. Density functional theory models indicated that propylene adsorbed to a metal site along the Ï bond would show a Raman spectrum very similar to gas-phase propylene except for out-of-plane C-H vibrations, which would be moved to higher energy. This adsorption spectrum, with out-of-plane vibrations shifted to higher energy, was observed for both TS-1 and Au/TS-1. Langmuir adsorption isotherms were generated for both TS-1 and Au/TS-1, and a scaling factor derived from propylene uptake experiments allowed these isotherms to be scaled to propylene coverage of titanium. / Ph. D.

Polylactide homopolymers with pendent carboxylic acid functional groups have been designed and synthesized to be studied as magnetite nanoparticle dispersion stabilizers. Magnetic nanoparticles are of interest for a variety of biomedical applications including magnetic field-directed drug delivery and magnetic cell separations. Small magnetite nanoparticles are desirable due to their established biocompatibility and superparamagnetic (lack of magnetic hysteresis) behavior. For in-vivo applications, it is important that the magnetic material be coated with biocompatible organic materials to afford dispersion characteristics or to further modify the surfaces of the complexes with biospecific moieties. The acid-functionalized silane endgroup was utilized as the dispersant anchor to adsorb onto magnetite nanoparticle surfaces and allowed the polylactide to extend into various solvents to impart dispersion stability. The homopolymers were complexed with magnetite nanoparticles by electrostatic adsorption of the carboxylates onto the iron oxide surfaces, and these complexes were dispersible in dichloromethane. The polylactide tailblocks extended into the dichloromethane and provided steric repulsion between the magnetite-polymer complexes. The resultant magnetite-polymer complexes were further incorporated into controlled-size nanospheres. The complexes were blended with poly(ethylene oxide-b-D,L-lactide) diblock copolymers to introduce hydrophilicity on the surface of the nanospheres with tailored functionality. Self-assembly of the PEO block to the surface of the nanosphere was established by utilizing an amine terminus on the PEO to react with FITC and noting fluorescence. / Ph. D.

Superparamagnetic nanoparticles have potential applications in targeted drug delivery and as magnetic resonance imaging contrast agents. Magnetite clusters are of particular interest for these applications because they provide higher magnetic flux (under a magnetic field) than individual magnetite nanoparticles, are biocompatible, and their size and compositions can be controlled. This thesis involves the controlled synthesis and characterization of clusters composed of magnetite nanoparticles stabilized with an amphiphilic block copolymer. It outlines a method to design and form well-defined and colloidally stable magnetite clusters. A Multi Inlet Vortex mixer (MIVM) was used because it is a continuous process that yields particles with relatively narrow and controlled size distributions. In the MIVM, four liquid streams collide under turbulent conditions in the mixing chamber where clusters form within milliseconds. The formation of magnetite clusters was studied in the presence of amphiphilic block copolymers containing poly (ethylene oxide) to provide steric stabilization and control of size distributions using flash nanoprecipitation. First, the mixer was tested using β-carotene as a model compound to form nanoparticles stabilized with an amphiphilic triblock copolymer poly(propylene oxide)-b-poly(ethylene oxide) (F127) at different Reynolds numbers and supersaturation values. Size analysis was done using dynamic light scattering and nanoparticle tracking analysis techniques. The cluster structure was studied using electron microscopy and magnetite compositions were measured using thermogravimetric analysis. Finally, the stability of magnetite clusters was studied over time and the effect of an applied magnetite field on the colloidal stability was investigated. / Master of Science

Copolymers that contain terminal or pendent functional groups have great potential in the biomedical area due to their biocompatibility and tunable properties.1-3 In this research, two vinyl functional epoxides, vinyldimethylsilylpropyl glycidyl ether (VSiGE) and ethoxy vinyl glycidyl ether (EVGE), were synthesized. These heterobifunctional monomers were polymerizable via the epoxide groups and can be functionalized via thiol-ene reactions through the pendent vinyl groups. A series of amphiphilic block copolyethers based on poly(ethylene oxide) and poly(1,2-butylene oxide) that incorporate VSiGE or EVGE were synthesized and characterized. The vinyl ether and vinyl silane functional groups were functionalized after polymerization and the functional polymers formed pH-sensitive micelles in aqueous medium. The copolyethers were loaded with ritonavir yielding well-controlled nanoparticles. Poly(L-glutamic acid) is comprised of naturally occurring L-glutamic acid repeating units that are linked together with amide bonds. In this research, we have prepared magnetic block ionomer complexes based on poly(ethylene oxide)-b-poly(L-glutamic acid) copolymers. This is of interest due to the biocompatibility and biodegradable nature of the poly(L-glutamic acid) component of the backbone. Allyl- and thiol-functional poly(ethylene oxide)-b-poly(L-glutamic acid) copolymers were also synthesized and coated onto the surface of iron oxide nanoparticles. Allyl- and thiol-tipped single particles were reacted with each other to prepare magnetic clusters. Transverse relaxivities of the clusters were found to be significantly higher than that of single particles. One major problem in commercial development of therapeutic proteins is their poor transport across cellular membranes and biological barriers such as the blood-brain barrier (BBB). One solution to this problem is to modify proteins with amphiphilic block copolymers such as PEO-b-PPO-b-PEO, Pluronics®. However, it isn't possible to independently tune the two PEO block lengths with commercial Pluronics® since a difunctional PPO macroinitator is utilized to grow both PEO blocks simultaneously (HO-EOn-b-POm-b-EOn-OH). Another challenge is introducing functional group which allows post-polymerization functionalization for specific applications. In this study, a series of heterobifunctional asymmetric amino-EOn1-b-POm-b-EOn2-OH block copolymers (APs) with different molecular weights of each block were synthesized and the amino terminal group was conjugated to an antioxidant enzyme, Cu/Zn superoxide dismutase (SOD1). The conjugates were characterized and their cellular uptake was investigated. / Ph. D.

yes / Controlling polymer thin-film morphology and crystallinity is crucial for a wide range of applications, particularly in thin-film organic electronic devices. In this work, the crystallization behavior of a model polymer, poly(ethylene oxide) (PEO), during spincoating is studied. PEO films were spun-cast from solvents possessing different polarities (chloroform, THF and methanol) and probed via in situ grazing incidence wide angle x-ray scattering. The crystallization behavior was found to follow the solvent polarity order (where chloroform < THF < methanol) rather than the solubility order (where THF > chloroform > methanol). When spun-cast from non-polar chloroform, crystallization largely followed Avrami kinetics, resulting in the formation of morphologies comprising large spherulites. PEO solutions cast from more polar solvents (THF and methanol) do not form well-defined highly crystalline morphologies and are largely amorphous with the presence of small crystalline regions. The difference in morphological development of PEO spun-cast from polar solvents is attributed to clustering phenomena that inhibit polymer crystallization. This work highlights the importance of considering individual components of polymer solubility, rather than simple total solubility, when designing processing routes for the generation of morphologies with optimum crystallinities or morphologies.

Ce travail a permis de démontrer que l’électrofilage, ainsi que l’électronébulisation, sont des méthodes faciles et efficaces de préparation de complexes entre des polymères et des petites molécules. En effet, la plupart des méthodes de préparation de complexes donnent des mélanges inhomogènes à cause de la cristallisation cinétiquement favorisée des petites molécules. Or, un mélange inhomogène peut être très difficile à caractériser. Dans ce travail, l’électrofilage a été utilisé pour la première fois avec succès pour obtenir des nanofils de complexe entre le poly(oxyde d’éthylène) (PEO) et le NaSCN (PEO-NaSCN) ainsi qu’entre le PEO et l’hydroquinone. L’électronébulisation a été utilisée pour obtenir du complexe entre la polycaprolactone (PCL) et l’urée. L’électrofilage n’était pas possible pour le système PCL-urée parce que la solubilité n’était pas suffisante pour atteindre la viscosité minimale requise pour l’électrofilage. L’électronébulisation peut donc complémenter l’électrofilage et rendre la technique applicable à encore plus de systèmes. Les systèmes ont été caractérisés par spectroscopie infrarouge (FT-IR), par diffraction de rayons X (XRD), par calorimétrie différentielle à balayage (DSC) et par microscopies optique et électronique à balayage. / This work has allowed to show that electrospinning, as well as electrospraying, are easy and efficient methods for preparing complexes between polymers and small molecules. Most complex preparation methods yield inhomogeneous mixtures because of the kinetically favoured crystallization of small molecules. An inhomogeneous mixture can be very difficult to characterize. In this work, electrospinning was used for the first time to obtain nanofibres of complexes between poly(ethylene oxide) (PEO) and NaSCN (PEO-NaSCN) as well as between PEO and hydroquinone. Electrospraying was used to obtain a complex between polycaprolactone (PCL) and urea. Electrospinning was not possible for the PCL-urea system because the solubility was not sufficient to attain the minimal viscosity required for electrospinning. Electrospraying can thus be used as a complementary technique to electrospinning, making this approach applicable to a much wider range of systems. The systems were characterized by infrared spectroscopy (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and microscopy (optical and scanning electronic microscopy).

Este trabalho apresenta um estudo sobre a síntese e propriedades do copolímero poli(l,l-lactídeo-stat-e-caprolactona)-bloco-poli(óxido de etileno)-bloco-poli(l,l-lactideostat-e-caprolactona). Poli(óxido de etileno) de massa molar 20.000 u.m.a. e poli(óxido de etileno) modificado, preparado a partir de poli(glicol etilênico) de massa molar 4.000 u.m.a., foram selecionados para o processo da síntese. A reação foi feita pela polimerização por abertura de anel em massa a 120ºC usando octoanato de estanho como iniciador. A composição química de cada amostra foi determinada com auxílio de RMN-1H e RMN-13C e suas propriedades mecânicas foram verificadas e comparadas utilizando análises térmicas como DMTA, DSC, TG e a aplicação da MEV como análise complementar. A observação pelas fotos de MOLP permitiu a visualização do comportamento de nucleação dos copolímeros e as características de sua cristalinidade. Seu grau de cristalinidade e as fases cristalinas foram identificados por difração de raios X (WAXS). A biocompatibilidade do material também foi examinada pela cultura de células. Os resultados de caracterização indicam o sucesso da copolimerização, as propriedades elastoméricas e, sua não citotoxidade comprovaram a possibilidade do uso destes copolímeros como biomateriais. Contudo, o tempo prolongado de reação e baixa incorporação do monômero lactídeo ainda são questões a serem melhoradas para a viabilização do copolímero como material de implante na área biomédica. / This work includes the study of the synthesis and characterization of the copolymer poly(l,l-lactide-stat-e-caprolactone)-b-PEG-b-poly(l,l-lactide-stat-e-caprolactone). Poly (ethylene oxide) with molar weight 20.000 and poly(ethylene oxide) modified, prepared from poly(ethylene oxide) with molar weight 4000 have been selected for this synthesis process. The reaction was done by ring-opening bulk polymerization, using stannous octoate as initiator at 120ºC. The chemical composition of samples were determined by 1H-NMR and 13C-NMR and their mechanical properties were verified using thermal analyses like DMTA, DSC and TG. Scanning electron microscopy (SEM) was applied as a complementary analysis. The pictures of polarizing optical microscopy showed us the copolymer\'s nucleation behaviors and their respective crystallization. The degrees of crystallinity and phase of copolymers were determined by WAXS. The biocompatibility of the copolymer was examined by cell cultivation test. The result of these analyses above indicated the success of synthesis. Their rubbery properties and non-toxicity allowed their application as biomaterial. However, the long reaction time and low incorporation of monomer of lactide might to be improved to increase its potential use in biomedical area in the future.

Estima-se que há mais de 50 anos, as furadeiras elétricas (FE) têm sido empregadas em cirurgias ortopédicas nos hospitais brasileiros para a perfuração óssea. Trata-se de equipamento elétrico, termossensível, não indicado para uso cirúrgico, não avaliado anteriormente quanto à eficácia da esterilização, suspeitando-se de risco potencial para infecções do sítio cirúrgico ou relacionadas a próteses ortopédicas. Os objetivos desse estudo foram: avaliar a carga microbiana de FE do uso cirúrgico e avaliar a eficácia da esterilização por óxido de etileno (ETO) de FE novas intencionalmente contaminadas. Trata-se de pesquisa experimental, laboratorial, randomizada e aplicada desenvolvida no laboratório de pesquisas experimentais da Escola de Enfermagem da Universidade de São Paulo. O trabalho foi realizado em duas fases. As condições assépticas foram rigorosamente seguidas para o controle das variáveis. Quinze FE analisadas na fase I, tiveram distribuição aleatória e cega, capturadas em um centro cirúrgico de um hospital escola. Foram cultivados: o ar gerado pelo motor e alíquotas de 10 µL do lavado das superfícies interna e externa das FE. Ainda nessa fase foi realizado um controle positivo onde uma FE foi contaminada com Serratia marcescens e um teste do método de filtração por membrana de porosidade de 0,45 µm com uma FE limpa, onde as membranas que filtraram diferentes quantidades do lavado foram cultivadas. Na fase II foram analisadas 22 FE e três perfuradores de osso (PO). Dezesseis FE constituíram o grupo experimental (GE), seis o controle positivo (GCP) e três PO constituíram o controle negativo (GCN). Todos os equipamentos previamente limpos e esterilizados foram submetidos à contaminação com esporos de Bacillus atrophaeus. As FE do GCP foram analisadas após a exposição ao contaminante, furadeiras do GE e perfuradores do GCN foram submetidos à limpeza e esterilização por ETO antes de serem analisados. Foram cultivados: ar gerado pelo motor e membrana filtrante após a filtração do lavado das superfícies interna e externa dos equipamentos. Foram realizadas coloração e microscopia: Gram para culturas positivas; Wirtz-Conklin para culturas positivas com bacilos Gram positivos. Os resultados mostraram que a carga microbiana de FE do uso cirúrgico é baixa e foi detectada em duas ocasiões no cultivo do ar, 1 ufc/FE e em uma ocasião no cultivo de alíquotas do lavado, 9 ufc/FE. O controle positivo realizado com Serratia marcescens comprovou a sensibilidade do método para amostras contendo alta concentração de contaminantes. O método filtração por membrana mostrou-se sensível para detectar baixa contaminação das FE, sendo o eleito para o teste de esterilidade. Os controles positivos apresentaram crescimento do microrganismo contaminante, comprovando a aderência ao material. Os controles negativos não apresentaram crescimento. Das 16 FE do GE, duas apresentaram crescimento sendo cada uma delas de 1ufc do contaminante inicial respectivamente no cultivo do ar e no cultivo da membrana. Foi comprovada a eficiência de 99,99999881% do processo de esterilização por ETO, com a probabilidade de sobrevivência de 1,19 x 10-8. Nas condições do desenvolvimento do experimento, a eficácia da esterilização das FE por ETO foi comprovada / Electric drills have been used to perform orthopedic surgeries in Brazilian hospitals for almost more than 50 years. This electric equipment is heat-sensitive and it is not appropriate to use in surgical procedures. Until now the efficacy of sterilization of this item had been not evaluated as a potential risk for the occurrence of surgical site infection or infection related to orthopedic prosthesis. The objectives of this study were to evaluate the bioburden of the used electric drills and to evaluate the sterility of the new electric drills contaminated artificially. It is an experimental and randomized study performed in the research laboratory of the Nursing School of the São Paulo University. The study was performed in two phases following rigorous aseptic techniques to control the variables. In the first phase fifteen electric drills were taken in the operating room of the university hospital and included in the study using aleatory and blind methods. Cultures were performed from the air produced by the drill engine and the aliquots of 10µL of the rinsed water from the internal and external surface of the electric drill. One electric drill was included as a positive control and was contaminated with Serratia marcescens. A membrane filter with porous of 0,45 µm were cultured after had been exposed to the rinsed water from the internal and external surface of the clean electric drill. In the second phase were analyzed twenty two electric drills and three orthopedic drilling machines. Sixteen electric drills were included in the experimental group, six were the positive control group and three orthopedic drilling machines in the negative control group. All the equipments previously cleaned and sterilized were submitted to the contamination with Bacillus atrophaeus. The electric drills included in the positive control group were analyzed after exposed to the contaminant and the electric drills of the experimental group and orthopedic drills included in the negative control group were submitted to clean and ethylene oxide sterilization before to start the analysis. The air produced by the drill engine and the membrane filter after exposed to the rinsed water of the internal and external surface of the electric drill were cultured. It was performed Gram microscopy and Wirtz-Conklin to Gram positive bacilli. The results showed low bioburden in the electric drills in two episodes. So, 1 cfu/electric drill was found in one episode of the air culture and 9 cfu/electric drill in one episode of culture of the aliquot. The positive control with Serratia marcescens demonstrated the sensibility of the method in samples with high concentration of contaminants. The method of membrane filtration showed sensible to detect low bioburden of the electric drills. So it is elected for the sterility test. The positive controls showed the growth of the contaminant microrganism demonstrating the adherence to the material surface. The negative controls did not show growth. Two of the sixteen electric drills included in the experimental group showed each one growth of 1cfu of the initial contaminant of the air and the membrane cultures respectively. So the efficiency of the sterilization process was 99,99999881% and the probability of find survivor was 1,19 x 10-8. In these conditions the study demonstrates that the efficacy of the ethylene oxide sterilization was proved