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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Development of polyhipe chromatography and lanthanide-doped latex particles for use in the analysis of engineered nanoparticles

Hughes, Jonathan Mark January 2013 (has links)
The aims of this thesis were two-fold: A) To use high internal phase emulsion (HIPE) templated materials to produce a chromatographic stationary phase for the size separation of engendered nanoparticles (NPs). B) To produce well characterised lanthanide doped polymer NPs with a potential use as analytical standards. Initially, silica materials were prepared from oil-in-water HIPEs by a two stage acid/base catalysed sol gel process. As well as presenting the expected macroporosity typical of HIPE templated materials, it was also found that micro- and meso-porosity could be influenced by surfactant choice and reaction with iron (III) chloride or copper (I) chloride which had been included in the HIPE. However, the resulting silica materials were deemed inappropriate for the desired chromatography. Monolithic columns were prepared from HIPE templated polymers (polyHIPEs) and incorporated into a HPLC system. Poly(styrene-co-divinylbenzene) and poly(ethylene glycol dimethacrylate) polyHIPE columns were able to separate sub-micron polystyrene latexes, detected by UV absorption, and dysprosium doped polystyrene latex particles and gold nanoparticles detected by inductively coupled plasma mass spectrometry (ICP-MS).Dysprosium, gadolinium and neodymium doped polystyrene NPs were prepared by micro-emulsion polymerisation. Particle size was controlled (over a 40 – 160 nm range) by tailoring of surfactant and initiator concentrations. Particles were characterised by dynamic light scattering, differential centrifugal sedimentation, transition electron microscopy and hydrodynamic chromatography (HDC)-ICP-MS. Also, particle surface change, lanthanide content and solids content were analysed. The latter two appear related to particle size. As far as the author is aware there are no cases of the use of polyHIPE columns size separation in the literature. Nor are there any cases of encapsulation of metals within polymer nanoparticles by micro-emulsion polymerisation reported.
2

Desenvolvimento de sistemas híbridos luminescentes - Polímero:európio(III) com estabilidade térmica e fotoluminescente / Development of hybrid systems of polymer:europium (III) with thermal stability and photostability

Forster, Pedro Lima 16 April 2015 (has links)
O polímero de policaprolactona (PCL) dopado com [Eu (TTA) 3 (H2O) 2] no complexo 1, 2, 5, 10 e 15% de concentrações foram preparadas e as suas propriedades térmicas e de luminescência discutidas. As bandas de absorção de infravermelho no intervalo de 1800-1550 cm-1 correspondente ao ν sensível (C = O) foram seleccionados para a técnica de ajuste de curva de desconvolução e confirmou-se que os picos de componentes são deslocados gradualmente com o aumento da concentração de dopagem. O deslocamento do ν (C = O) banda para os β-dicetonato complexos para novas posições nos sistemas dopados (pCLE) proporcionam boa evidência de que o ião de metal está coordenado aos átomos de oxigénio dos grupos carbonilo PCL. Calorimetria exploratória diferencial (DSC) não mostraram alterações significativas na segunda temperatura de fusão (Tm2) para as amostras de cinema. No entanto, a cristalinidade é afectada pelo complexo dopante em materiais de polímero em maior concentração. A análise termogravimétrica (TGA) não mostra nenhuma perda de peso na gama de 50-200 ° C para os sistemas poliméricos dopados, corroborando a interacção da matriz de polímero com Eu3 + complexo n por substituição das moléculas de água no complexo precursor. A observação das bandas de emissão característicos resultantes das transições 5D0 → 7FJ (J = 0-4) dominadas pela hipersensibilidade transição 5D0 → 7F2 em torno de 614 nm, de íon Eu3 +, indicando que a incorporação de Eu3 + complexo no sistema de polímero. O valor da eficiência quântica de emissão de nível 5D0 para os materiais poliméricos dopados (η = 40-62%) são mais elevados do que para o complexo [Eu (TTA) 3 (H2O) 2] complexo (η = 29%), sugerindo que o matriz de polímero actua como co-sensibilizador do processo de luminescência. / The polycaprolactone (PCL) polymer doped with [Eu(tta)3(H2O)2] complex at 1, 2, 5, 10 and 15 % concentrations were prepared and their thermal and luminescence properties discussed. The IR absorption bands in the range of 18001550 cm1 corresponding to the sensitive ν(C=O) were selected for the deconvolution curve-fitting technique and was confirmed that the component peaks are gradually shifted with the increase of doping concentration. The displacement of the ν(C=O) band for the β-diketonate complex to new positions in doped systems (PCLE) provide good evidence that the metal ion is coordinated to the oxygen atoms from the PCL carbonyl groups. Differential scanning calorimetry (DSC) showed no significant changes in second melting temperature (Tm2) for the film samples. However, crystallinity is affected by the dopant complex in the polymer materials at higher concentration. Thermogravimetric analysis (TGA) shows no weight loss in the range of 50200 °C for the doped polymeric systems, corroborating the interaction of the polymer matrix with the Eu3+-complex by substitution of the water molecules in the complex precursor. The observation of the characteristic emission bands arising from the 5D0 → 7FJ transitions (J=0-4) dominated by the hypersensitive 5D0 → 7F2 transition at around 614 nm of Eu3+ ion, indicating the incorporation of the Eu3+ complex in the polymer system. The value of the emission quantum efficiency of 5D0 level for the doped polymer materials (η = 40 - 62 %) are higher than for the [Eu(TTA)3(H2O)2] complex (η = 29 %), suggesting that the polymer matrix acts as co-sensitizer of the luminescence process.
3

Desenvolvimento de sistemas híbridos luminescentes - Polímero:európio(III) com estabilidade térmica e fotoluminescente / Development of hybrid systems of polymer:europium (III) with thermal stability and photostability

Pedro Lima Forster 16 April 2015 (has links)
O polímero de policaprolactona (PCL) dopado com [Eu (TTA) 3 (H2O) 2] no complexo 1, 2, 5, 10 e 15% de concentrações foram preparadas e as suas propriedades térmicas e de luminescência discutidas. As bandas de absorção de infravermelho no intervalo de 1800-1550 cm-1 correspondente ao ν sensível (C = O) foram seleccionados para a técnica de ajuste de curva de desconvolução e confirmou-se que os picos de componentes são deslocados gradualmente com o aumento da concentração de dopagem. O deslocamento do ν (C = O) banda para os β-dicetonato complexos para novas posições nos sistemas dopados (pCLE) proporcionam boa evidência de que o ião de metal está coordenado aos átomos de oxigénio dos grupos carbonilo PCL. Calorimetria exploratória diferencial (DSC) não mostraram alterações significativas na segunda temperatura de fusão (Tm2) para as amostras de cinema. No entanto, a cristalinidade é afectada pelo complexo dopante em materiais de polímero em maior concentração. A análise termogravimétrica (TGA) não mostra nenhuma perda de peso na gama de 50-200 ° C para os sistemas poliméricos dopados, corroborando a interacção da matriz de polímero com Eu3 + complexo n por substituição das moléculas de água no complexo precursor. A observação das bandas de emissão característicos resultantes das transições 5D0 → 7FJ (J = 0-4) dominadas pela hipersensibilidade transição 5D0 → 7F2 em torno de 614 nm, de íon Eu3 +, indicando que a incorporação de Eu3 + complexo no sistema de polímero. O valor da eficiência quântica de emissão de nível 5D0 para os materiais poliméricos dopados (η = 40-62%) são mais elevados do que para o complexo [Eu (TTA) 3 (H2O) 2] complexo (η = 29%), sugerindo que o matriz de polímero actua como co-sensibilizador do processo de luminescência. / The polycaprolactone (PCL) polymer doped with [Eu(tta)3(H2O)2] complex at 1, 2, 5, 10 and 15 % concentrations were prepared and their thermal and luminescence properties discussed. The IR absorption bands in the range of 18001550 cm1 corresponding to the sensitive ν(C=O) were selected for the deconvolution curve-fitting technique and was confirmed that the component peaks are gradually shifted with the increase of doping concentration. The displacement of the ν(C=O) band for the β-diketonate complex to new positions in doped systems (PCLE) provide good evidence that the metal ion is coordinated to the oxygen atoms from the PCL carbonyl groups. Differential scanning calorimetry (DSC) showed no significant changes in second melting temperature (Tm2) for the film samples. However, crystallinity is affected by the dopant complex in the polymer materials at higher concentration. Thermogravimetric analysis (TGA) shows no weight loss in the range of 50200 °C for the doped polymeric systems, corroborating the interaction of the polymer matrix with the Eu3+-complex by substitution of the water molecules in the complex precursor. The observation of the characteristic emission bands arising from the 5D0 → 7FJ transitions (J=0-4) dominated by the hypersensitive 5D0 → 7F2 transition at around 614 nm of Eu3+ ion, indicating the incorporation of the Eu3+ complex in the polymer system. The value of the emission quantum efficiency of 5D0 level for the doped polymer materials (η = 40 - 62 %) are higher than for the [Eu(TTA)3(H2O)2] complex (η = 29 %), suggesting that the polymer matrix acts as co-sensitizer of the luminescence process.
4

A 6-beam combiner using superimposed volume index holographic gratings

Yum, HoNam 01 November 2005 (has links)
In this thesis, a 6-beam combiner using multiplexed holograms in dye-doped polymer is investigated. It is realized by recording six superimposed holographic gratings, which show uniform diffraction efficiency. The coupled wave theory for N superimposed gratings is more generalized and is used to analyze the amplitudes of diffracted waves in three different boundary conditions. Multiple-ring diffracted beam analysis is proposed to determine the dynamic range of a holographic material. The M/# is evaluated by recording a single hologram and counting the number of ring patterns in the diffracted beam. This analysis is extended to assess the equalized grating strength of N superimposed holograms. Six holograms with the equalized grating strength which can be assigned within the dynamic range of our material and show maximum diffraction efficiency are recorded. The phase locking of five beams to one reference beam is performed using PZT controller. The designs of lock-in amplifier, ramp generator and servo using commercial chips are demonstrated. The readout set-up used to split one single beam into six coherent copies is presented. The function of each part of the PZT controller in the readout set-up is discussed in detail. The intensity profile of an N-beam combiner is investigated by varying the phase angle between adjacent input waves. The entire solution which describes the amplitude of a combined beam is derived from generalized coupled wave theory. A simplified experimental set-up without a complicated PZT controller is demonstrated using a planoconvex lens. In order to provide six coherent light sources in future work, the injection locking of a single laser diode to the master laser diode is performed. An expected read-out setup is proposed to carry out both the achievement of six coherent sources and a 6 beam combination.
5

Effets orientationnels induits par la photo-isomerisation spiropyrane-merocyanine dans un film de polymere soumis a un champ electrique.

Hosotte, Sophie 10 January 1996 (has links) (PDF)
Ce travail est axe sur l'etude des effets orientationnels induits par photo-isomerisation et de la relaxation de l'ordre cree. La methode que nous utilisons est basee sur la possibilite de certains materiaux de devenir dichroiques et birefringents lorsqu'ils sont eclaires par une lumiere polarisee et d'acquerir des proprietes non-lineaires du premier ordre, si un champ electrique est applique simultanement. Cette methode permet d'induire, par voie optique, un ordre orientationnel a partir de molecules photo-isomerisables. Cette orientation est la consequence de la superposition de plusieurs mecanismes: le pompage selectif des molecules paralleles a la polarisation de la pompe, la redistribution angulaire (non-centrosymetrique s'il y a un champ) et enfin, la relaxation angulaire. Ce modele a deja ete demontre sur la molecule de disperse red 1 (derivee de l'azobenzene), mais, du fait de la brievete de la duree de vie du photo-isomere, il est impossible de determiner les differentes etapes de la rotation des molecules. Une experience de dichroisme photo-induit a ete realisee pour observer l'anisotropie des deux isomeres de la molecule. Cette experience a montre que la rotation est faible a chaque cycle de pompage mais qu'il est pratiquement impossible de determiner a quel moment du cycle la molecule tourne. Nous montrons alors, sur le systeme spiropyrane-merocyanine, que la longue duree de vie du photo-isomere permet d'obtenir des informations sur les mecanismes d'orientation. Dans le cas du spiropyrane, l'orientation a lieu aussi bien pendant la photo-isomerisation que par diffusion thermique spontanee apres la photo-isomerisation. D'autre part, ces experiences ont permis d'etudier la mobilite angulaire des molecules de merocyanine dans le polymere: elle est d'autant plus faible que la concentration des echantillons est grande, elle diminue en fonction du temps apres le processus de photo-isomerisation et elle est plus faible dans le cas d'echantillons ages. Notre etude a permis une meilleure comprehension des mecanismes d'orientation lies a la photo-isomerisation et de relaxation de l'ordre orientationnel.

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