M. Tech. Chemical Engineering. / Discusses the scope of this research study composes of three interactive steps. The first step involves the design of the specific zeolite system (ZSM-5) and the set-up of an autoclave reactor for the hydrothermal synthesis of this and other zeolites and nano materials, then the oxidation catalyst (TS-1) development, i.e. the substitution of aluminium with titanium in the zeolite framework, and finally the formulation and preparation of the isomorphous Silicalite zeolite by omitting the aluminium in the synthesis. And further, set-up of suitable equipments and apparatus for the catalytic testing of the Titanium Silicalite-1 in the oxidation reaction of phenol as the test reaction. Therefore, the overall objectives of this research are: set up an autoclave reactor for the hydrothermal synthesis, formulation of a synthesis recipe for MFI family of catalysts in the laboratory, synthesis of ZSM-5, Silicalite-1, and TS-1 zeolites catalysts in the laboratory, characterization and optimization of the of catalysts listed above, testing the Ti-Silicalite catalyst in the oxidation reaction of phenol with hydrogen peroxide, as the oxidant, set up analytical system (Gas Chromatography, ASS) for analysis of catalyst performance in the oxidation reaction, Evaluate the conversion of the reaction and the selectivity of the individual catalysts reaction Evaluate the conversion of the reaction and the selectivity of the individual catalysts reaction and verify results obtained and compare with systems described in the literature.

This dissertation mainly addresses the synthesis of well-ordered mesoporous titania thin films by dip coating with PEO-PPO-PEO triblock copolymer surfactant template P123. Because P123 is composed of poly(ethylene oxide) [PEO] and poly(propylene oxide) [PPO] blocks, concentrations of ingredients are adjusted to tune the films’ wall thickness, pore size and mesophase. Structural changes are consistent with partitioning of species among PEO blocks, PPO blocks, and the PEO/PPO interface. Titanates localize near PEO and increase wall thickness (by 5 nm to 7 nm). Depending on aging temperature, PPG either swells the PPO cores (when it is hydrophobic) or introduces large (>200 nm) voids (when it is hydrophilic but phase separates during heating). 1-butanol localizes at the PEO/PPO interface to favor a 3D hexagonal mesostructure. In another approach, anodizing Ti foils yields vertically aligned titania nanotubes arrays with exceptional stabilities as anodes in lithium ion batteries; they maintain capacities of 130-230 mAhg-1 over 200 cycles. No microstructural changes are induced by battery cycling and good electrical contact is maintained. A diffusion induced stress model suggests that thin-walled nanotubes arrays should be stable under testing conditions, and that ordered hexagonal columnar pore arrays should have both high charge/discharge rates and low stress development.

It is common knowledge that water is one of the basic needs for human beings. However, the consumption of contaminated water can lead to waterborne diseases and fatalities. It is, therefore imperative to constantly monitor the quality of potable water. There are numerous technologies used for water quality monitoring. These technologies are relatively effective however these tests are expensive and complex to use, which then require experienced technicians to operate them. Other tests are not rapid, making consumers of water susceptible to waterborne diseases. In this study, dye-doped, surface functionalized silica nanoparticles (SiNPs) and surface-functionalized magnetic nanocomposites (MNCs) were proposed as materials that can be applied in order to reduce the time taken to get results as well as to make the processes less complex and portable. The aim of this study was to synthesize and characterize surface functionalized dye-doped SiNPs and surface functionalized MNCs for detection and preconcentration of in water. Additionally, proof of concept had to be shown using the synthesized materials. SiNPs were the materials of choice due to their easily functionalized surfaces and their strong optical properties. SiNPs are photostable and they do not leach in solution due to the inert nature of the silica matrix in aqueous media. MNCs were chosen as materials of choice for preconcentration of E. coli in water because they are easy to synthesize and they can be applied in various biological applications due to their functional groups. SiNPs were synthesized using the water-in-oil microemulsion. The SiNPs were further functionalized with amine and carboxyl groups and avidin. Thereafter, they were bioconjugated with biotinylated anti-E. coli antibodies. The pure and surface functionalized SiNPs were characterized using ATR-FTIR spectroscopy, FE-SEM, HR-TEM, Zeta Sizer, UV-vis spectroscopy and spectrofluorometry. The application of the dye—doped surface functionalized SiNPs in E. coli detection was characterized using the fluorescence plate reader. The SiNPs were spherical and uniform in size. They increased in size as they were being functionalized, ranging from 21.20 nm to 75.06 nm. The SiNPs were successfully functionalized with amine and carboxyl groups as well as with avidin and antibodies. Two methods were investigated for carboxyl group attachment (direct and indirect attachment) and the direct attachment method yielded the best results with a surface charge of -31.9 mV compared to -23.3 mV of the indirect method. The dye loading was found to be 1% after particle synthesis. The optical properties of the Ru(Bpy) dye were enhanced 3 fold when they were encapsulated in the Si matrix. The SiNPs were binding to the E. coli cells and enabled detection. MNCs were synthesized through in-situ polymerization. The MNCs were characterized using ATR-FTIR spectroscopy, SEM, TEM and XRD. The MNCs were successfully functionalized with carboxyl groups. The increase in size of the nanocomposites as seen in SEM images proved that the Fe3O4 was successfully encapsulated in the polymer matrix. The MNCs were proven to be magnetic by a simple magnetism test whereby they were separated in an aqueous solution using an external magnetic field. The antibody-labelled MNCs were binding to the E. coli cells as shown in TEM images. E. coli cells were removed from water at varying concentrations of 1x106 CFU/mL to 1x109 CFU/mL at 10 mL volumes. This study has demonstrated that dye-doped SiNPs amplify the signal of E. coli cells using fluorescence. The study has also demonstrated that the MNCs can be applied in sample preconcentration and enrichment for E. coli detection. However, further studies should investigate and optimize the combination of the two techniques in a point of use device for water quality testing of 100 mL-samples as per the requirement of the SANS 241 standard. / Civil and Chemical Engineering / M. Tech. (Chemical Engineering)

Orientador: Sergio Gama / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-09T01:21:06Z (GMT). No. of bitstreams: 1 Rocco_DanielLeandro_D.pdf: 7791593 bytes, checksum: 4428135e865b15fec8e5338713adba04 (MD5) Previous issue date: 2006 / Resumo: No presente trabalho são apresentados os resultados da avaliação do Efeito Magnetocalórico (EMC) das cerâmicas manganitas e do intermetálico La(Fe,Si)13. Para as manganitas foram produzidas amostras do tipo Tr1-x Mx MnO3(com Tr = terra-rara e M = alcalino-terroso). Em alguns conjuntos de amostras variou-se a quantidade x, ou seja, mudou-se a relação entre o Mn3+ e Mn 4+. Em outro conjunto a quantidade x era fixada em 0,4 e fazia a substituição da terra-rara pelo alcalino-terroso. Isto tinha como efeito a alteração do valor do raio iônico médio do sítio A <rA>. As amostras obtidas foram caracterizadas por difração de raios-X com refinamento Rietveld, metalografia óptica, e medidas magnéticas. Estas últimas permitiram o cálculo do EMC, que foi avaliado em função de x e de <rA>. Chegou-se a conclusão que à medida que < rA> diminuí há um aumento do acoplamento spin-rede que promove uma mudança do caráter da transição magnética de segunda para primeira ordem, provocando, portanto, um aumento do EMC. O outro material estudado foi o sistema metálico La(Fe,Si)13, cujo método de obtenção é por meio de fusão em forno a arco. Na verdade, é assim que todos os trabalhos da literatura sugerem preparar esta liga. Porém, descobriu-se neste trabalho de doutorado um intervalo de imiscibilidade, ainda não reportado na literatura, que origina-se no sistema binário La-Fe, e se expande para a liga ternária. Este fato tem implicações importantíssimas, pois comprova que apenas pelo processo de fusão da liga não é possível a obtenção deste material de forma monofásica. Então, se propõe uma nova forma de preparação do material que consiste na fusão em forno a arco com uma posterior pulverização das amostras e um tratamento térmico por longos períodos em atmosfera inerte / Abstract: In the present work we show the results of the Magnetocaloric effect evaluation for ceramics manganites and for La(Fe,Si)13 intermetallic. The manganites sample produced were of Tr1-x Mx Mn O3 (Tr = rare-earth and M = alkaline earth) type. In one sample group it was changed the quantity x, or equivalently, the relation between the Mn3+ and Mn4+. On the other sample set, the x amount was fixed in 0.4 and the replacement was from the rare-earth to alkaline earth. This had as effect the variation of the value of the average ionic radius (<rA>) of site A. The samples that obtained were characterised by x-Rays diffraction with Rietveld analyses, optic metallographic and magnetic measurements. The latter made possible the calculation of the MCE, which was evaluated as a function of x and < rA>. We conclude that as soon as <rA> diminishes there is an increase of the spin-lattice coupling that promotes a change in the magnetic transition order, causing, than, an increase of MCE. The second material studied was the metallic system La(Fe,Si )13, which preparation method is by arc-melting. In fact, in other works this material was obtained using this technic, but it was discovered in this Ph. D. work an immiscibility interval, until now not reported. This miscibility gap has its origin in the binary La-Fe phase diagram, and it extends for ternary alloy. This fact has an important implication, because it shows that with only the fusion process of the alloy it is impossible to obtain a single phase material. So, we propose a new way for material preparation that consists in the arc-melting with followed by sample milling and heat-treatment for a long time in an inert atmosphere / Doutorado / Física da Matéria Condensada / Doutor em Ciências

Orientador: Elias Basile Tambourgi / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-11T04:08:18Z (GMT). No. of bitstreams: 1 Freitas_JeffersonArlen_D.pdf: 3985383 bytes, checksum: 8a45be364ed2c151ea51fbb373ede3d6 (MD5) Previous issue date: 2007 / Resumo: Este trabalho tratou da pesquisa e desenvolvimento de um adsorvente alternativo, aplicável no tratamento de rejeitos líquidos industriais, contendo baixas concentrações dos metais pesados Cd, Cu e Zn. Ele teve como objetivo geral produzir esferas adsorventes de zeólita 4A - Sargassum sp. com custo de produção competitivo e com elevada capacidade de captura dos metais pesados Cd, Cu e Zn, nas quais o processo de adsorção ocorra com elevada eficiência e com cinética favorável. A produção das esferas envolveu uma abordagem inovadora do Processo Sol - Gel, a qual permitiu produzir sete tipos de esferas, partindo da combinação e imobilização de adsorventes tradicionais pesquisados: biomassa Sargassum sp., caulim, alumina e zeólita. Este processo de imobilização das partículas dos adsorventes tradicionais causa uma obstrução dos poros e canais existentes nestas partículas e, com isto, reduz a capacidade de captura dos metais pesados nas esferas resultantes. Felizmente, a combinação de adsorventes realizada viabilizou a obtenção de esferas adsorventes com elevada capacidade de captura de metais pesados e com cinética favorável. É o caso das esferas de zeólita 4A, com capacidade máxima de captura de Cd+Cu+Zn de 746 µmol/g, com uma velocidade de captura aproximada de 18 µmol/g.h e com uma eficiência de captura de 82% e das esferas de zeólita 4A - 50% em peso de Sargassum sp., com capacidade máxima de captura de Cd+Cu+Zn de 709 µmol/g, com uma velocidade de captura aproximada de 20 µmol/g.h e com uma eficiência de captura de 83%. O comportamento de adsorção destas esferas se ajustou ao modelo de equilíbrio de Freundlich. Elas possuem uma cinética de adsorção compatível com o modelo cinético de pseudo-segunda ordem. Ao tratarem um efluente industrial real, estas esferas apresentam uma eficiência de captura de Cd+Cu+Zn =90% enquanto que numa resina quelante comercial esta eficiência é de 99,5%. Tem-se, pois, esferas adsorventes com elevada eficiência e baixo custo de produção, tornando-as um bom adsorvente para aplicação no tratamento de efluentes líquidos industriais com baixa concentração de Cd, Cu e Zn / Abstract: In this work had been made a research and the development of an alternative adsorbent which may be applied in the treatment of industrial liquid effluents containing low concentration of heavy metals, Cd, Cu and Zn. The main objective was to produce 4A type zeolite-Sargassum sp. adsorbents spheres with the following characteristics: competitive fabrication cost; high uptake capacity of the heavy metals, Cd, Cu and Zn; high affinity by the referred heavy metals; and appropriated adsorption kinetic. The marking of the adsorbents spheres had involve the innovative use of the Sol-gel Process. That had permitted to obtain seven types of adsorbents spheres for combination and immobilization of the particles of traditional adsorbents Sargassum sp., kaolin, alumina and 4A type zeolite. This immobilization process causes an obstruction of the pores and the channels present in these particles that reduced the uptake capacity of the produced adsorbents spheres. Fortunately, the combination of traditional adsorbents particles produced adsorbent spheres with high uptake capacity, high uptake efficiency, and appropriate adsorption kinetic. As, two types of adsorbent spheres, 4A type zeolite and 4A type zeolite-50% Sargassum sp. adsorbed 746 µmol/g and 709 µmol/g with an adsorption velocity of 18 µmol/g.h and 20 µmol/g.h, and a uptake efficiency of 82% and 83%, respectively. The adsorption behavior of these adsorbent spheres had been fitting to the Freundlich model. They have an adsorption kinetic compatible with the pseudo-second order model. When it treated an industrial liquid effluent with these adsorbent spheres, they showed a uptake efficiency higher than 90% and while an uptake efficiency of 99,5% is shown for the commercial chelant resin / Doutorado / Sistemas de Processos Quimicos e Informatica / Doutor em Engenharia Química

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The use of various ‘smart materials’ (briefly meaning materials that respond to a change in their environment) is currently of interest to both academics and industry. The primary aim of the current study was to entrap photochromic (PC) dyes in miniemulsions, as a means to improve their fatigue resistance, thus synthesizing smart nanoparticles. In the coatings industry the use of aqueous systems is becoming a common requirement for health and environmental reasons. Miniemulsion entrapment allows the direct dispersion of PC dyes into aqueous systems while allowing for the opportunity to tailor-make the host matrix in order to obtain a suitable PC response and improved fatigue resistance. The optimal instrument set-up required to establish the PC response of films of the so-called smart nanoparticles (i.e. PC miniemulsions) was determined. A UV-Vis instrument with a chip-type UV LED mounted inside for activation of the samples provided PC response results. A tungsten lamp with filter provided deactivation of the samples. A stable butyl methacrylate (BMA) miniemulsion formulation was established by conducting a design of experiments. A chromene and spironapthoxazine (SNO) PC dye were entrapped in the BMA miniemulsion. A hindered amine light stabiliser (HALS) was also entrapped with the SNO dye in the BMA miniemulsion to further improve the fatigue resistance. The following PC properties of the smart nanoparticles films were evaluated: colourability, thermal decay rate, half-life and fatigue resistance. To compare results with conventional systems, a BMA solution polymer was prepared. The SNO dye and different concentrations of the HALS were mixed with the BMA solution polymer. In comparison to the SNO smart nanoparticles the chromene smart nanoparticles films had lower colourability, but better fatigue resistance. Incorporating HALS at levels of 0.5–2% in the BMA miniemulsion with PC dye did not lead to any significant improvement in fatigue resistance, yet films of the BMA solution polymer showed some improvement. SNO dye incorporated at 1% gave similar colourability in both miniemulsion and in solution polymer, yet the fatigue resistance of the films of the PC miniemulsions was much better. / AFRIKAANSE OPSOMMING: Die gebruik van verskeie “slim materiale’ (kortliks beskryf as materiale wat reageer op `n verandering in hul omgewing) is tans van belang vir beide akademici en die industrie. Die hoofdoel van hierdie studie was om miniemulsietegnologie te gebruik om fotochromiese (FC) kleurstowwe vas te vang, vir die sintese van slim nanopartikels, om sodoende die weerstand teen afgematheid te verbeter. In die verfindustrie word die gebruik van waterbasissisteme meer algemeen weens gesondheids- en omgewingsredes. Die gebruik van miniemulsie sisteme om materiale vas te vang maak dit moontlik om FC kleurstowwe direk in waterbasissisteme te meng. Die sintese van `n unieke gasheer matriks word benodig om die optimum FC verandering te toon en weerstand teen afgematheid te verbeter. Om die FC verandering van die sogenaamde slim nanopartikel films (d.w.s. FC miniemulsies) te ondersoek was `n gepaste instrumentele opstelling nodig. Dit is vasgestel dat `n UV-Vis instrument waarin `n skyfie-tipe UV LED gemonteer is vir aktivering van die monsters, reproduseerbare resultate gegee het. Die monsters is gedeaktiveer deur gebruik te maak van `n tungsten lig met ‘n filter. `n Eksperimentele ontwerp is toegepas om `n stabiele butielmetakrielaat (BMA) miniemulsie formulasie te verkry. `n ‘Chromene’ en ‘spironapthoxazine’ (SNO) FC kleurstof is in die BMA miniemulsie vasgevang tesame met `n verhinderde amien ligstabiliseerder (VALS) om die weerstand teen afgematheid verder te verbeter. Die volgende FC eienskappe van die slim nanopartikels is gemeet: kleurintensiteit, tempo van termiese verwering, half-lewe en weerstand teen afgematheid. `n BMA polimeeroplossing is berei om resultate mee te vergelyk. Die SNO kleurstof en verskillende konsentrasies van die VALS is met die BMA polimeeroplossing gemeng. In vergelyking met die slim SNO nanopartikels het die intelligente chromene nanopartikelfilms `n swakker kleurintensiteit gehad, maar `n hoër weerstand teen afgematheid. Die gebruik van 0.5–2% VALS in die BMA miniemulsie met FC kleurstof het minimale verbetering in weerstand teen afgematheid getoon, maar daar was wel `n beduidende verbetering in die geval van films met FC kleurstof in `n BMA polimeeroplossing. Byvoeging van 1% SNO kleurstof in `n BMA miniemulsie of polimeeroplossing het dieselfde kleurintensiteit gelewer, maar die weerstand teen afgematheid van die FC miniemulsie was baie beter.

Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The need to analyse and detect volatile organic compounds (VOCs) at trace levels has led to the development of specialized sample preparation techniques. The requirement for trace analysis of VOCs stems from the negative effects they have on the environmental and human health. Methods for the analysis of non-polar VOCs commonly found as trace contaminants in water and analysis of more polar oxygenated compounds commonly found in zero-VOC water-based paints were developed. Solid phase micro extraction (SPME) was employed and extraction of the majority of the target analytes could be achieved at levels below 0.3 μg.l-1. In an attempt to further improve the detection of these two target analyte groups, novel materials based on poly(dimethyl siloxane) (PDMS) were investigated as possible extraction phases for VOCs, with the focus specifically on the analysis of the polar analytes in paint. Conventional free radical polymerization was used to synthesize poly(methyl methacrylate-graft-poly(dimethyl siloxane) (PMMA-g-PDMS), poly(methacrylic acid)-graft-poly(dimethyl siloxane) (PMAA-g-PDMS), polystyrene-graftpoly( dimethyl siloxane) (PSty-g-PDMS) and poly(butyl acrylate)-graft–poly(dimethyl siloxane) (PBA-g-PDMS). These polymers have a copolymer functionality which presents a series of different polarities. The MMA-g-PDMS and MAA-g-PDMS as well as the homopolymers were electrospun into nanofibers. The low glass transition temperature and molecular weight of the PBAg- PDMS meant that this polymer could not be electrospun. Scanning electron microscopy (SEM) was used to study the fiber morphology of the electrospun fibers and the non-beaded fibers were further investigated. Polyacrylonitrile-graft-poly(dimethyl siloxane) (PAN-g-PDMS) previously synthesized and electrospun by another member of the group were also investigated for use as possible extraction material in volatile analysis. The thermal stability of the nanofibers at 200°C was studied using thermal gravimetric analysis (TGA). This property is important since after the target analytes are extracted using the nanofibers, elevated temperatures are used to thermally desorp the volatile analytes from the extraction materials prior to GC analysis. The PAN-g-PDMS, MMA-g-PDMS and PMMA showed no significant weight loss during thermal evaluation, however, it was observed that the PMMA and PMMA-g-PDMS nanofibers looses their nanostructure and that the PAN-g-PDMS nanofibers changes colour from white to yellow to rust brown. The polymers based on MAA showed weight losses of more than 10% after one hour of exposure to the elevated temperatures, but the nanostructure remained intact. The PAN-g-PDMS, PMAA-g-PDMS and PMAA nanofibers were evaluated as possible extraction materials for VOC analysis. The nanofibers were evaluated using a similar approach to that of stir bar sorptive extraction (SBSE). Headspace sorptive extraction (HSSE) using a commercially available PDMS stir bar and the novel materials were used to evaluate the extraction efficiency of the different materials. The optimized extraction method developed using SPME were employed for the extraction using the nanofibers and PDMS stir bar. It was noted that the nanofibers lose their extraction capabilities during the first extraction/desorption cycle possibly due to thermal degradation therefore each of the materials can only be used in a single extraction. The majority of the non-polar analytes were extracted using the nanofibers at levels of 500 μg.l-1, however it was noted that the commercially available SPME extraction materials and the PDMS stir bar had superior extraction efficiencies for the specific target analytes. In the evaluation of the nanofibers for extraction of the more polar oxygenated analytes it was noted that 2-Ethylhexylacrylate was the only analyte to be extracted by all of the materials. The PAN-g-PDMS extracted three of the four analytes at levels of 100 μg.l-1. At lower analyte concentrations of 10 μg.l-1 only two of the four acrylate compounds were detected using the PAN-g-PDMS nanofibers. Ethyl acrylate was not extracted by any of the novel materials, whereas in SPME using the CAR/PDMS fiber, the LOD was determined to be below 1 μg.l-1. Although these materials were not superior to the commercially available phases, this is only the case for the specific target analytes analyzed. / AFRIKAANSE OPSOMMING: Die behoefte vir die analiese van vlugtige organiese verbindings (VOS) op spoorvlak, het gelei tot die ontwikkeling van gespesialiseerde monster voorbereidingstegnieke. Die vereiste vir die spoor analiese van die VOS het ontstaan uit die negatiewe uitwerking wat hierdie stowwe het op die omgewing en menslike gesondheid. Metodes vir die analiese van nie-polêre VOS wat algemeen voorkom as spoorkontaminante in water en polêre suurstofryke verbindings wat algemeen voorkom in nul-VOS water-gebaseerde verf was ontwikkel. Soliede fase mikro-ekstraksie (SFME) was gebruik, en die ekstraksie van die meerderheid van die teikenstowwe kon gedoen word op vlakke laer as 0,3 μg.l-1. In 'n poging om die opsporing van hierdie twee teiken analietgroepe verder te verbeter, is nuwe materiale gebaseer op polidimetielsiloksaan (PDMS), ondersoek as moontlik ekstraksiefases vir VOS, met die fokus spesifiek op die analiese van die polêre stowwe in verf. ’n Konvensionele vrye radikaal polimerisasieproses was gebruik om poli (metiel- metakrilaat)-entpoli( dimetielsiloksaan) (PMMA-g-PDMS), poli(metakrilaatsuur)-ent–poli (dimetielsiloksaan) (PMAA-g-PDMS), polistireen-ent-poli(dimetielsiloksaan) (PSty-g-PDMS) en poli(butielakrilaat)- ent-poli(dimetielsiloksaan) (PBA-g-PDMS) te sintetiseer. Hierdie ko-polimere het 'n kopolimeer funksionaliteit wat 'n reeks van verskillende polariteite bied. Die MMA-g-PDMS en MAA-g-PDMS sowel as die homopolimere was ge-elektrospin in orde om nanovesels te vorm. Die lae glasoorgangstemperatuur en molekulêre gewig van die PBA-g-PDMS het beteken dat hierdie polimeer nie elektrospin kon word nie. Skandeerelektronmikroskopie (SEM) was gebruik om die veselmorfologie van die ge-elektrospinde vesels te bestudeer en die nanovesels wat ’n eweredige oppervlak gehad het, was verder ondersoek. Poliakrilonitriel-ent-poli(dimetielsiloksaan) (PAN-g- PDMS) wat voorheen gesintetiseer en ge-elektrospin was deur 'n ander lid van die groep is ook ondersoek vir gebruik as moontlik ekstraksiemateriaal vir die analiese van vlugtige stowwe. Die termiese stabiliteit van die nanovesels was by 200°C bestudeer met behulp van ‘n termiese gravimetriese analiese (TGA) instrument. Hierdie eienskap is belangrik, aangesien die teikenstowwe by hoë temperature van die nanovesels gedesorbeer word voor die GC-analiese. Die PAN-g-PDMS, MMA-g-PDMS en PMMA het geen beduidende gewigsverlies tydens termiese evaluering gehad nie, alhoewel dit egter waargeneem was dat die PMMA en PMMA-g-PDMS nanovesels hulle nanostruktuur verloor en dat die PAN-g-PDMS nanovesels se kleur verander van wit na geel na roesbruin gedurende die termiese analiese. Die polimere wat gebaseer was op MAA het ’n gewigs-verlies van meer as 10% getoon na 'n uur van blootstelling aan die verhoogde temperature, maar die nanostruktuur het ongeskonde gebly. Die PAN-g-PDMS, PMAA-g-PDMS en PMAA nanovesels was geëvalueer as moontlike ekstraksiemateriale vir VOS-analiese. Die nanovesels was geëvalueer met 'n soortgelyke benadering tot dié van “stir bar“ sorpsie ekstraksie (SBSE). Bo-ruimte sorpsie ekstrasie is gebruik om die ekstraksie-doeltreffendheid van die verskillende materiale (kommersiële PDMS en nanovesels) te evalueer. Die geoptimaliseerde ekstraksiemetode ontwikkel in SFME was gebruik vir die ekstraksie van die VOS met die nanovesels en die PDMS “stir bar“. Dit was waargeneem dat die nanovesels hul ekstraksievermoë verloor tydens die eerste ekstraksie/desorpsie siklus, moontlik as gevolg van termiese degradasie dus, kon die materiale slegs ‘n enkele maal gebruik word vir die ekstraksie. Die meerderheid van die nie-polêre stowwe was ge-ëkstraeer deur gebruik te maak van die nanovesels op vlakke van 500 μg.l -1, maar die kommersieel beskikbare SFME ekstraksie materiale en die PDMS “stir bar“ se ekstraksie-doeltreffendheid vir die spesifieke stowwe was beter. In die evaluering van die nanovesels vir die ekstraksie van die meer polêre suurstofryke stowwe was daar waargeneem dat 2- etielheksielakrilaat die enigste analiet was wat ge-ëkstraeer was deur al die materiale. Die PAN-g- PDMS kon drie van die vier polêre stowwe op vlakke van 100 μg.l-1 opspoor. By laer analietkonsentrasies van 10 μg.l-1 kon slegs twee van die vier akrilaat verbindings opgespoor word deur gebruik te maak van hierdie nanovesels. Etielakrilaat was nie ge-ëkstraeer deur enige van die nuwe materiale nie, terwyl in SFME met die gebruik van die CAR/ PDMS vesel, die analiet op vlakke onder 1 μg.l-1 opgespoor kon word. Alhoewel hierdie nuwe materiale nie beter is as die kommersieel beskikbare ekstraksiemateriale nie is dit net die geval vir die spesifieke teiken analietgroepe wat ondersoek was in hierdie studie.

Nanoalloys are an exciting new class of materials in the growing field of nanotechnology. Nanoalloys consist of the nanoscale co-aggregation of two or more metals with a potential to form compositionally-ordered phases or superstructures that have properties unlike those of the individual metal clusters or of bulk alloys of the constituent metals. This research seizes the opportunity that the nanoscale domain has to offer, and focuses on the synthesis of iron and cobalt nanoalloys via the simultaneous decomposition of iron cobalt organometallic precursors in a stabilizing environment, accompanied by the thorough characterization of the resulting nanoclusters. Zero-valent FeCo nanoalloys may potentially have interesting uses as magnetic materials. Since these clusters have sizes less than the size of their magnetic domain, the clusters will exhibit single domain magnetism. This magnetism may be observed by the presence of chain structures of FeCo nanoclusters due to the alignment of their single magnetic domains. In order to create a near-atomically homogeneous nanoalloy without preferential aggregation of its metal atom constituents, no clustering and phase separation should take place. In the bulk, alloys of iron and cobalt phase separate over most of the compositional range. Conversely, at the nanoscale, it may be possible to synthesize nanoalloy structures that are not normally favorable at given compositions, by the manipulation of reaction kinetics. In order to produce an atomically mixed nanoalloy, the transformation reactions of the organometallic precursors should display similar kinetic features, i.e. similar reaction rates. Therefore, the reaction kinetics of all the species in the reaction must be similar to avoid competition between them. As a result, kinetic control of the individual transformation reaction rates of each species may be used to modulate the aggregation and phase separation of the different species, and consequently control cluster morphology. This work has provided the framework for the design of synthesis methods that enable the control of the structure of FeCo nanoalloys with careful attention to precursor decomposition kinetics and the correlation between reaction kinetics and nanoalloy morphology.

Orientador: Cecilia Amelia de Carvalho Zavaglia / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-24T20:34:28Z (GMT). No. of bitstreams: 1 Cardoso_HugoAnaniasInacio_D.pdf: 8008219 bytes, checksum: ac8d13454298a5718b0e0051a87eb944 (MD5) Previous issue date: 2014 / Resumo: O fosfato tricálcico (TCP) é um dos fosfatos de cálcio mais importantes dentre os utilizados como biomateriais devido à sua biocompatibilidade, bioatividade, biorreabsorbilidade e osteocondutividade. A fase ? (?-TCP) se destaca, principalmente, devido à sua conversão em hidroxiapatita deficiente em cálcio após implantação. Entretanto, é difícil obter ?-TCP de elevada pureza, o que prejudica sua reatividade e seu desempenho in vivo. O objetivo principal deste trabalho é sintetizar ?-TCP de elevada pureza. Para isso, o pó de ?-TCP foi obtido via reação de estado sólido. Os reagentes precursores foram sintetizados em laboratório a fim de se diminuir o nível de impurezas, principalmente o magnésio. Após analisados e validados, os reagentes foram misturados nas devidas proporções e o pó de ?-TCP calcinado sob diversos protocolos: diferentes temperaturas sob mesmo tempo de patamar; mesma temperatura sob diferentes tempos de patamar; mesmo tempo e temperatura de patamar com condições de resfriamento distintas. Analisou-se a influência de cada variável na cinética da reação: tempo, temperatura, resfriamento. Foi obtido pó de ?-TCP (2g) com 100% de pureza sob temperaturas (1265ºC) e tempos (2h) menores que os registrados em literatura, sem a necessidade de choque térmico. O protocolo foi validado também para grandes quantidades de material (50g), em que o nível de pureza também foi de 100% / Abstract: Tricalcium phosphate (TCP) is one of the most important calcium phosphates used as biomaterials due to their biocompatibility, bioactivity, osteoconductivity and bioresorbability. Among them, ?-TCP goes beyond due to its conversion into calcium deficient hydroxyapatite after implantation. However, it is difficult to obtain high purity ?-TCP, which prejudices its reactivity and its performance in vivo. The main purpose of this work is to synthesize high purity ?-TCP. For this, ?-TCP powder was obtained by solid state reaction. The precursor reagents were synthesized in the laboratory in order to reduce the level of impurities, particularly magnesium. After analyzed and validated, reagents were mixed in the proper proportions and ?-TCP powder calcined under various protocols: variable temperature and constant time; constant temperature and variable time; constant time and temperature with different cooling conditions. The influence of each variable on the reaction kinetics was evaluated: time, temperature and cooling. ?-TCP powder (2g) was obtained with 100 % purity at temperatures (1265 °C) and times (2h) lower than those mentioned in the literature without thermal shock. The protocol was also validated for more material mass (50g), wherein the purity level was also 100% / Doutorado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica

This thesis begins with a brief analysis of the synthetic methodologies utilized in polymer science. A conclusion is drawn inferring that upper limits in molecular design are inevitable, arising as a direct consequence of the predominance of covalent strategies in the field. To address these concerns, the universal polymer backbone (UPB) concept has been hypothesized. A UPB has been defined as any copolymer, side-chain functionalized with multiple recognition elements that are individually capable of forming strong, directional, and reversible non-covalent bonds. Non-covalent functionalization of these scaffolds can lead to the formation of a multitude of new polymer structures, each stemming from a single parent or universal polymer backbone. To prepare such a UPB, isomerically pure exo-norbornene esters containing either a PdII SCS pincer complex or a diaminopyridine residue were synthesized, polymerized, and copolymerized via ROMP. All polymerizations were living under mild reaction conditions. Kinetic studies showed that the kp values are highly dependent upon the isomeric purity but completely independent of the terminal recognition units. Non-covalent functionalization of these copolymers was accomplished via 1) directed self-assembly, 2) multi-step self- assembly, and 3) one-step orthogonal self-assembly. This system shows complete specificity of each recognition motif for its complementary unit with no observable changes in the association constant upon functionalization. To explore potential applications of this UPB concept, random terpolymers possessing high concentrations of pendant alkyl chains and small amounts of recognition units were synthesized. Non-covalent crosslinking using a directed functionalization strategy resulted in dramatic increases in solution viscosities for metal crosslinked polymers with only minor changes in viscosity for hydrogen bonding motifs. The crosslinked materials were further functionalized via self-assembly by employing the second recognition motif, which gave rise to functionalized materials with tailored crosslinks. This non-covalent crosslinking/functionalization strategy could allow for rapid and tunable materials synthesis by overcoming many difficulties inherent to the preparation of covalently crosslinked polymers. Finally, the current status of the UPB concept is reviewed and methodological extensions of the concept are suggested. Evaluation of how UPBs may be used to optimize materials and their potential use in fabricating unique electro-optical materials, sensors, and drug delivery vesicles are explored.