Dispositivos eletroluminescentes poliméricos apresentam alto potencial tecnológico, principalmente devido ao fato de ser possível a obtenção de dispositivos flexíveis e de grande área. Apesar disto, ainda existem alguns fatores que limitam a sua aplicação tecnológica, como por exemplo o tempo de vida e a eficiência na emissão dos dispositivos. Alguns métodos têm sido propostos para o aumento destes fatores, entre os quais estão a inserção de camadas transportadoras de elétrons e buracos. Esta tese teve como objetivo principal a busca por métodos que possibilitassem a melhora das propriedades elétricas e/ou ópticas dos dispositivos eletroluminescentes poliméricos (PLEDs). Neste contexto, filmes Langmuir-Blodgett (LB) da camada emissiva e da camada transportadora de elétrons foram aplicados nos PLEDs, devido a reprodutibilidade e ao grau de organização destes filmes, o que possibilita uma emissão polarizada. Além disso, observou-se aumento na injeção eletrônica nos dispositivos com o uso de ionômeros como camada transportadora de elétrons. Por outro lado, a combinação da POMA e ITO como eletrodo transparente no dispositivo com PPV+DBS como camada ativa (ITO/POMA/PPV+DBS/Al) mostrou a diminuição da tensão de operação quando comparado a um dispositivo convencional (lTO/PPV/Al). Os dispositivos foram caracterizados através de medidas elétricas e opto-elétricas. / Polymer electroluminescent devices are promising for a number of applications, in particular due to the possibility of obtaining large area, flexible displays. There are, however, major stumbling blocks associated with the short lifetimes and limited efficiency and brightness of light-emitting diodes (LEDs) fabricated with organic molecules in comparison with the inorganic ones. Severa1 methods have been proposed to increase brightness and eficiency, which include the use of electron and/or hole transporting layers adjacent to the electrodes. ln this thesis, we report the study of severa1 methods to improve the efficiency of the polymer light emitting diodes (PLEDs). In this context, Langmuir-Blodgett (LB) films were used in PLEDs, as emitting and electron transport layer, due to the high degree of thickness control, low number of defects, and some degree of organization at the molecular scale. Besides, improvements in electron injection into the emissive layer using ionic polymers (ionomers) as electron-transporting layers were observed. Othenvise, the combination of POMA and ITO as transparent electrode and PPV+DBS as active layer (ITO/POMA/PPV+DBS/A1) leads to a decrease in the operating voltage compared with the conventional PLED, ITO/PPV/Al. The devices were characterized by electrical and opto-electrical measurements.

Au cours de ce travail, nous nous sommes intéressés à l’élaboration de cristaux photoniques colloïdaux d’architecture contrôlée afin d’étudier leur effet sur les spectres de photoluminescence de luminophores. Notre stratégie a été d’incorporer les émetteurs au sein des particules de silice composant les cristaux colloïdaux de façon à les répartir de manière homogène dans l’ensemble des matériaux. Nous présentons la synthèse des précurseurs minéraux et l’élaboration de cristaux colloïdaux d’épaisseur contrôlée à la couche près grâce à la technique de Langmuir-Blodgett. Ces structures sont caractérisées par une bande interdite qui affecte la propagation de la lumière. L’insertion d’une couche de particules de diamètre différent dans un cristal colloïdal induit l’apparition d’une bande passante au sein de la bande interdite. Nous avons ainsi étudié l’influence de la structure de cristaux avec et sans défaut(s) sur les spectres d’émission de différents luminophores. Nous avons observé une inhibition et une exaltation locale de la lumière émise dans les zones spectrales correspondant respectivement aux bandes stoppante et passante. Nous avons également observé des modifications réversibles des spectres de photoluminescence des émetteurs, lorsque ceux-ci sont incorporés au sein de cristaux colloïdaux dont les propriétés optiques peuvent être modulées via l’application d’un stimulus extérieur. / During this work, we were interested in the elaboration of colloidal photonic crystals with a controlled architecture to study their effect on the photoluminescence spectra of emitters. Our strategy was to incorporate the emitters within the silica particles composing the colloidal crystals in order to distribute them homogeneously in the samples. We present the synthesis of the mineral precursors and the elaboration of colloidal crystals whose thickness is controlled at the layer level thanks to the Langmuir-Blodgett technique. These structures are characterized by a band gap which affects the light propagation. Insertion of a monolayer of particles with a different size as a planar defect within a colloidal crystal leads to the formation of a pass band in the band gap. We thus studied the effect of the structure of crystals with or without planar defect(s) on the emission spectra of different emitters. We observed local inhibition and exaltation of the emission in the spectral region corresponding to the stop band and the pass band, respectively. We have also observed reversible modulations of the photoluminescence spectra of the emitters when these ones were incorporated in colloidal crystals whose optical properties can be tuned by an external stimulus.

Explorou-se a caracterização de monocamadas e filmes LB de polianilina (PANi), e um oligômero de polianilina, chamado aqui de 16-mero, com estearato de cádmio (CdSt). A análise dos filmes de Langmuir indicou que possivelmente não há mistura em nível molecular da PANi e do 16-mero com CdSt, ainda que a quantidade adicionada em solução de polímero ou oligômero influencie a estabilidade das monocamadas. Utilizou-se UV-vis, FTIR, difração de raios-X, condutividade elétrica, elipsometria, microscopia óptica e potencial de superficie para caracterização dos filmes LB. Os resultados de UV-vis indicaram uma transferência uniforme e ainda que os filmes recém depositados encontram-se desdopados. A análise de FTIR confirma a presença de CdSt nos filmes LB, e o efeito de desdopagem em subfases neutras, corroborando os resultados de UV-vis. A difração de raios-X indica a presença de domínios separados de PANi (e 16-mero) com CdSt nos filmes LB. Resultados elipsométricos indicaram uma espessura por camada em tomo de 25 &#197. A excelente uniformidade obtida nos filmes LB mistos foi comprovada pelos resultados de microscopia óptica e potencial de superficie. Esses filmes mistos apresentaram valores de condutividade elétrica em tomo de 10-4 a 10-5 S.cm-1 (van der Pauw), tanto para a PANi quanto para o 16-mero. Investigou-se também o efeito da exposição dos filmes mistos PANi/CdSt aos raios-X. Nota-se um deslocamento para a região do vermelho, na região do visível, nos espectros de UVvis, similar à observada pela dopagem através de ácidos inorgânicos. Verificou-se que os efeitos de umidade da atmosfera de medida são predominantes nesse processo de dopagem. É feita uma análise dos resultados de condutividade elétrica, comparando-os com os encontrados na literatura. / A study has been made of composite Langmuir and Langmuir-Blodgett (LB) films of polyaniline (PANi), and a polyaniline oligomer (l6-mer polyaniline), with cadmium stearate (CdSt). The monolayers studies pointed to a phase separated system containing the polymer (or the 16-mer) and CdSt, with no mixing at the molecular leveI, although the relative contents of PANi and 16-mer in the solution have a strong influence on the monolayer stability. UV-vis, FTIR, X-ray difIraction (XRD), electrical conductivity, ellipsometry, optical microscopy and surface potential measurements were used in the LB film characterization. UV-vis results have shown a uniform transfer, with the as deposited films in the undoped state. FTIR results confirmed the presence of CdSt and undoped polyaniline (and 16-mer) in the transferred LB films, corroborating the UV-vis results. XRD has shown separated domains of CdSt and PANi (l6-mer also) in the LB films. Ellipsometry data indicated a thickness of 25 &#197 per deposited layer. The high uniformity in these mixed LB films was confirmed by optical microscopy and surface potential measurements. The electrical conductivity was approximately 10-4 to 10-5 S.cm-1 for both PANi and 16-mer. Mixed PANi/CdSt films were also exposed to X-ray irradiation. After a given dose rate there is a red shift in the UV-vis spectra from the 600 nm region to the 800 nm region, similar to the usual acid doping process observed in polyaniline. Humidity effects have a strong influence on the doping process. A comparison is made of the conductivity measurements made here with those reported in the literature.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第19193号 / 農博第2132号 / 新制||農||1034(附属図書館) / 学位論文||H27||N4939(農学部図書室) / 32185 / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 髙野 俊幸, 教授 西尾 嘉之, 教授 木村 恒久 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Botulinum Neurotoxin (BoNT) is one of the most potent toxins known to human kind. The Atomic Force Microscope (AFM) was employed to investigate the conditions under which BoNT type A heavy chain would bind and/or insert into mica supported dipalmitoylphosphatidylcholine (DPPC) lipid bilayers. As an alternate technique, DPPC/GT1b or total ganglioside extract (80:20) monolayers of a Langmuir Blodgett (LB) Trough were adapted to be artificial membrane models for toxin insertion studies. We conclude that LB monolayer studies are a promising candidate for BoNT/A membrane insertion investigation. Botulinum neurotoxin serotype A insertions into the LB monolayers in the presence of BoNT/A low affinity ganglioside receptor alone, independent of pH. This thermodynamic evidence indicates that BoNT/A may begin its heavy chain insertion into the cholinergic nerve ending before endocytosis and acidification.

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Les nombreuses morphologies périodiques des copolymères blocs sont bien connues. L'immiscibilité des blocs de nature chimique différente conduit à une séparation de phases à l'échelle moléculaire. Cette caractéristique propose une voix intéressante pour la préparation de surfaces nano-structurées. La couche monomoléculaire du poly(acrylate de tert-butyle)-bloc-poly(méthacrylate de méthyle) déposée à l'interface air-eau produit une séparation de phases en deux dimensions qui donne lieu à une surface composée de domaines. La taille de ces domaines correspond aux dimensions moléculaires qui sont elles-mêmes reliées aux masses moléculaires des blocs. Cette structure est conservée lors du transfert de la monocouche sur un substrat solide par la technique de Langmuir-Blodgett et la morphologie peut donc être étudiée par la microscopie à force atomique (AFM). Nos recherches portent sur l'étude de la taille et de l'organisation de ces domaines dans les films monomoléculaires. Nous avons synthétisé le poly(acrylate de tert-butyle) et le poly(acrylate de tert-butyle)-bloc-poly(méthacrylate de méthyle) par polymérisation anionique afin d'obtenir des échantillons monodisperses de différentes masses molaires. Par la suite, la morphologie des films minces monomoléculaires est étudiée par la microscopie à force atomique. Les images de microscopie à force atomique montrent une structure périodique composée de domaines. Étonnamment, des images semblables sont obtenues pour les échantillons d'homopolymères. Une hypothèse envisagée est que l'utilisation d'a-méthyle styrène lors de l'initiation de la polymérisation pourrait donner un très pefit bloc poly(a-méthyle styrène) au début de la molécule et ainsi induire la formation de micelles. Des images AFM de nouveaux polymères synthétisés sans l'a-méthyle styrène ne montrent pas la présence de domaines. Donc, il n'y aurait pas, dans ce cas, présence de micelles de surfaces à l'interface air-eau.