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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

Polymères hydrocarbonés superhydrophobes élaborés par polymérisation électrochimique : une alternative à la chimie du fluor ? / Hydrocarbon superhydrophobic polymers from electrochemical polymerization : an alternative to fluorine ?

Wolfs, Mélanie 13 December 2013 (has links)
Une surface est dite superhydrophobe si l’angle de contact d’une goutte d’eau avec cette surface est supérieur à 150°. Les domaines d’application de telles surfaces anti-adhérentes sont variées : du bâtiment avec l’élaboration de vitres anti-salissures au biomédical pour empêcher ou limiter l’adhésion bactérienne en passant par l’aéronautique. La superhydrophobie provient de la combinaison de deux paramètres : la structuration de la surface et la faible énergie de surface du matériau. Dans la plupart des références de la littérature, l’élaboration de telles surfaces s’effectue en plusieurs étapes. La polymérisation électrochimique de monomères conducteurs est une technique simple, rapide et reproductible pour obtenir des surfaces superhydrophobes. En effet, en une seule étape, le film de polymère se dépose et se structure. Cette méthode permet de contrôler les propriétés de mouillage en jouant sur les paramètres électrochimiques (charge de dépôt, substrat, sel électrolyte) ou sur la structure chimique du monomère. Ce travail porte sur l’élaboration et la caractérisation de films de polymères conducteurs obtenus par électrodéposition de dérivés du 3,4-éthylènedioxythiophene (EDOT), du 3,4-ethylènethiathiophene (EOTT) et du 3,4-propylenedioxythiophene (ProDOT) portant une chaîne hydrocarbonée de longueur variable. Des surfaces aux propriétés de mouillage polyvalentes (hydrophiles à superhydrophobes) ont été obtenues. De plus, l’influence de la part chimie et de la part physique sur l’angle de contact à l’eau a été déterminée pour les EDOT hydrocarbonés. Ce travail contribue à trouver une alternative aux composés fluorés. dans la domaine de la superhydrophobie. / Controlling wettability of a solid surface is important in many practical applications. This property, resulting from the combination a low surface energy material with a surface structuration, is commonly expressed by the contact angle of a water droplet on the surface. Surfaces with a water contact angle (θwater) larger than 150° are usually called superhydrophobic surfaces. Such surfaces are very interesting because of their expected self-cleaning or anti-contamination properties, which could be applied in various applications such as in biomedical devices, paint or in aeronautics for example. Among all the techniques to prepare superhydrophobic surfaces, electrochemical polymerization is a fast and versatile technique. In current literature on this field, the general approach is the use of highly fluorinated tails to reach the water-repellency. However, as observed in nature, fluorine is not necessary and can present environmental impacts. In this work, we focused on the synthesis of original monomers with hydrocarbon chain as hydrophobic part in order to find alternative to fluorine chemistry to prepare electropolymerized superhydrophobic surfaces. We succeeded to reach high water repellency (θwater > 150°) with hydrocarbon conducting polymers and we determined the influence of chemical and physical parts onto the water contact angle. We also found similar dewetting properties than the fluorinated series meaning the hydrocarbon conducting polymers could be a real alternative to fluorine chemistry.
2

Preparação de um copolímero multieletrocrômico para aplicação em dispositivo ópticos / Preparation and characterization of a multielectrochromic copolymer for use in optical devices

Silva, Ana Júlia Cavalcante de 28 June 2012 (has links)
The copolymerization of different monomers is an interesting alternative to combine the properties of homopolymers as well as to obtain new colors in order to apply in electrochomic devices. The electrochemical synthesis of poly(DNBP-co-EDOT) was successfully achieved by the potentiodynamic and galvanostatic methods on the electrode surface. During the deposition of the copolymer it was observed that the films deposited by the potentiodynamic method were heterogeneous due to the presence of isolated nucleation sites. The films deposited by the galvanostatic method showed to be homogeneous and adherent to the electrode surface. The films of poly(DNBP), poly(DNBP-co-EDOT) and PEDOT were characterized by infrared spectroscopy technique, confirming the presence of major functional groups of the homopolymers in the structure of the copolymer. During electrochemical characterization by cyclic voltammetry of homopolymers and the copolymer it was possible to observe that the poly(DNBP-co-EDOT) has intermediate characteristics of the voltammograms of the homopolymers, showing a voltammogram characteristic of a capacitive device and displaying three different colors depending on the applied potential, besides having a high absorption in the near infrared region. The films of poly(DNBP), poly(DNBP-co-EDOT) and PEDOT characterized by SEM showed different morphologies, confirming the copolymerization. The films of poly(DNBP-co-EDOT) with Qdep = 30, 45 and 60 mC cm-2 were characterized by spectroelectrochemical, which techniques presented a coulombic efficiency of approximately 80%, chromatic contrast on the order of 30% in  = 585 nm and 50% in  = 1065 nm and coloration efficiency in the range of 177 C cm-2 for the reduction and 79.7 C cm-2 for the oxidation. Comparing these values with the data for the poly(DNBP) can be confirm that the films of poly(DNBP-co-EDOT) showed better electrochomic properties and are promising as active layer in optoelectronic devices such as displays and smart windows. Electrochomic devices was constructed with poly(DNBP-co-EDOT) an electrochomic electrode and PEDOT as an secondary electrode. The devices showed values of chromatic contrast of 13%, with good stability up to 500 cycles of charging / discharging / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A copolimerização de monômeros diferentes é uma alternativa interessante para combinar as propriedades dos homopolímeros como também produzir novas cores, visando aplicações eletrocrômicas. A síntese eletroquímica do poli(DNBP-co-EDOT) foi alcançada com sucesso pelos métodos potenciodinâmico e galvanostático na superfície do eletrodo. Durante a deposição do copolímero foi observado que o método potenciodinâmico formava filmes não homogêneos devido a presença de sítios de nucleação isolados. Em contra partida os filmes depositados pelo método galvanostático apresentaram-se homogêneos e aderentes à superfície do eletrodo. Os filmes de poli(DNBP), poli(DNBP-co-EDOT) e PEDOT foram caracterizados através da técnica de espectroscopia de infravermelho, confirmando a presença dos principais grupos funcionais dos homopolímeros no copolímero formado. Durante a caracterização eletroquímica por voltametria cíclica dos homopolímeros e do copolímero foi possível observar que o poli(DNBP-co-EDOT) possui caracteristicas intermediárias aos voltamogramas dos homopolímeros, apresentando um voltamograma característico de um dispositivo capacitivo e exibindo três cores distintas dependendo do potencial aplicado, além de apresentar uma alta absorção na região do infravermelho próximo. Os filmes de poli(DNBP), poli(DNBP-co-EDOT) e PEDOT caracterizados por MEV apresentaram morfologias diferentes, confirmando a copolimerização. Os filmes de poli(DNBP-co-EDOT) com Qdep = 30, 45 e 60 mC cm-2 foram caracterizados por técnicas espectroeletroquímicas, onde apresentaram uma eficiência coulômbica de aproximadamente 80 %, contraste cromático da ordem de 30 % em  = 585 nm e 50 % em  = 1065 nm e eficiência eletrocrômica na faixa de 177 C cm-2 para a redução e 79,7 C cm-2 para a oxidação. Comparando estes valores com os dados para o poli(DNBP) pode-se confirmar que os filmes de poli(DNBP-co-EDOT) mostraram melhores propriedades eletrocrômicas e são promissores como camada ativa em dispositivos optoeletrônicos, tais como displays e janelas inteligentes. Foram construídos dispositivos eletrocrômicos usando o poli(DNBP-co-EDOT) como eletrodo eletrocrômico e o PEDOT como eletrodo secundário. Os dispositivos apresentaram valores de T% próximos a 13% em  = 600 nm, com boa estabilidade até 500 ciclos de carga/descarga
3

Synthesis Of Benzimidazole Containing Donor Acceptor Electrochromic Polymers

Akpinar, Hava Zekiye 01 February 2011 (has links) (PDF)
ABSTRACT SYNTHESIS OF BENZIMIDAZOLE CONTAINING DONOR ACCEPTOR ELECTROCHROMIC POLYMERS Akpinar, Hava Zekiye M. Sc., Department of Chemistry Supervisor: Prof. Dr. Levent Toppare February 2011, 60 pages Donor-acceptor-donor (DAD) type benzimidazole (BIm) and 3,4-ethylenedioxythiophene (EDOT) bearing monomers (4-(2,3-Dihydrothieno[3,4-b][1,4]dioxin-5-yl)-7-(2,3 dihydrothieno[3,4b][1,4] dioxin-7-yl)-2-benzyl-1H-benzo[d]imidazole (M1), 2,4-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-7-(2,3-dihydrothieno[3,4-b][1,4]dioxin-7-yl)-1H-benzo[d]imidazole (M2) and 4-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-7-(2,3-dihydrothieno[3,4-b][1,4]dioxin-7-yl)-2-ferrocenyl-1H-benzo[d]imidazole (M3)) were synthesized and electrochemically polymerized. Pendant group at 2-C position of the imidazole ring was functionalized with phenyl (P1), EDOT (P2) and ferrocene (P3) in order to observe substituent effect on electrochemical and electrochromic properties of corresponding polymers. Spectroelectrochemical results showed that different pendant groups resulted in polymers with slightly different optical band gaps (1.75, 1.69 and 1.77 eV respectively) and different number of achievable colored states. Optoelectronic performance were reported in detail. Keywords: Benzimidazole, EDOT, Donor-Acceptor Type Polymers, Electrochromism, Conjugated Polymers.
4

Synthesis Of Benzimidazole Containing Donor Acceptor Electrochromic Polymers

Akpinar, Hava Zekiye 01 February 2011 (has links) (PDF)
ABSTRACT SYNTHESIS OF BENZIMIDAZOLE CONTAINING DONOR ACCEPTOR ELECTROCHROMIC POLYMERS Akpinar, Hava Zekiye M. Sc., Department of Chemistry Supervisor: Prof. Dr. Levent Toppare February 2011, 60 pages Donor-acceptor-donor (DAD) type benzimidazole (BIm) and 3,4-ethylenedioxythiophene (EDOT) bearing monomers (4-(2,3-Dihydrothieno[3,4-b][1,4]dioxin-5-yl)-7-(2,3 dihydrothieno[3,4b][1,4] dioxin-7-yl)-2-benzyl-1H-benzo[d]imidazole (M1), 2,4-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-7-(2,3-dihydrothieno[3,4-b][1,4]dioxin-7-yl)-1H-benzo[d]imidazole (M2) and 4-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-7-(2,3-dihydrothieno[3,4-b][1,4]dioxin-7-yl)-2-ferrocenyl-1H-benzo[d]imidazole (M3)) were synthesized and electrochemically polymerized. Pendant group at 2-C position of the imidazole ring was functionalized with phenyl (P1), EDOT (P2) and ferrocene (P3) in order to observe substituent effect on electrochemical and electrochromic properties of corresponding polymers. Spectroelectrochemical results showed that different pendant groups resulted in polymers with slightly different optical band gaps (1.75, 1.69 and 1.77 eV respectively) and different number of achievable colored states. Optoelectronic performance were reported in detail.
5

Conception de nouveaux matériaux conducteurs extensibles à base de multicouches de polyélectrolytes sur support silicone / Conception of new stretchable conducting materials based on polyelectrolyte multilayers on silicon substrate

Saint-Aubin, Christine de 20 September 2013 (has links)
Cette thèse propose tout d’abord une méthode originale, appelée 2 en 1, de construction contrôlée, couche-par-couche, de films de polyélectrolytes, basée sur le dépôt d’un unique complexe polycation-polyanion. Détaillée dans le cas du poly(éthylènedioxythiophène)-poly(styrènesulfonate) PEDOT-PSS, la méthode est ensuite étendue avec le même succès à d’autres complexes (poly(éthylèneimine) branché-poly(4 styrènesulfonate), poly(diallyldiméthylammonium)-poly(4 styrènesulfonate) et poly(allylamonium)-poly(4 styrènesulfonate)).Les films 2 en 1 de PEDOT PSS sont robustes vis-à-vis d’un recuit thermique et possèdent une conductivité électronique indépendante de leur épaisseur. Cette conductivité peut être améliorée en utilisant un composite contenant des nanoparticules d’or Au Np PEDOT PSS. Des superstructures alternant dépôts de PEDOT PSS et de composite ont, en outre, pu être construites.La construction est contrôlée non seulement sur des substrats rigides (verre, wafer de silicium) mais également sur des substrats élastomère de type silicone (polydiméthylsiloxane PDMS). Le traitement du PDMS par polymérisation plasma d’EDOT sous vide permet le dépôt subséquent de films 2 en 1 de PEDOT PSS. Par ailleurs, la pulvérisation cathodique d’or sur le PDMS permet d’obtenir des conducteurs étirables, de surcroît utilisables comme substrats de films 2 en 1 de PEDOT PSS.Enfin, de nouveaux complexes aqueux synthétisés par voie chimique à partir d’EDOT et d’un polysaccharide (sulfate de chondroïtine A) ont conduit à des films présentant une très bonne conduction qui peut être augmentée par inclusion de nanoparticules d’or. Ces nouveaux composés sont porteurs d’un potentiel très prometteur. / This thesis proposes firstly an original method, called 2 in 1 method, for controlled, layer-by-layer, polyelectrolytes film buildup, based on the deposition of a sole polycation-polyanion complex. Detailed on the case of poly(ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS), the method was then extended with the same success to other complexes (branched poly(ethyleneimine)-poly(4 styrenesulfonate), poly(diallyldimethylammonium)-poly(4 styrenesulfonate) and poly(allylamonium)-poly(4 styrenesulfonate)).The 2 in 1 PEDOT PSS films are robust regarding thermal annealing and have an electronic conductivity independent of their thickness. This conductivity can be improved by using a composite containing gold nanoparticles Au Np PEDOT PSS. Superstructures alternating PEDOT PSS and composite depositions were also obtained.Film buildup is controlled not only on rigid substrates (glass, silicon wafer) but also on elastomeric substrates of the silicon type (polydimethylsiloxane PDMS). The treatment of PDMS by vacuum plasma enhanced chemical vapor deposition (PECVD) of EDOT allows subsequent deposition of 2 in 1 PEDOT-PSS films. Besides, gold sputter deposition on PDMS reaches stretchable conductors. Gold sputtered PDMS can further act as a substrate for 2 in 1 PEDOT-PSS films.Finally, new aqueous complexes, chemically synthesized from EDOT and a polysaccharide (chondroitin sulfate A), lead to films which exhibit a very good conduction, which can be improved by the inclusion of gold nanoparticles. These new complexes are very promising in the field of conductive biomaterials.
6

SIMULACAO DA ESTRUTURA MOLECULAR E ELETRÔNICA DE POLIMEROS CONDUTORES

Andrade, Ageo Meier de 22 February 2016 (has links)
Made available in DSpace on 2017-07-24T19:37:54Z (GMT). No. of bitstreams: 1 Ageo Meier Andrade.pdf: 3358892 bytes, checksum: c2798e568b2f1bcb11fc21644c783df2 (MD5) Previous issue date: 2016-02-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The search for materials with conductive capacity has been gaining attention in the scienti c community for its many technological applications. Moreover, understanding the charge transport phenomena in these materials it is still seen as a challenge to the scientic community. Poly (3,4-ethylenedioxythiophene), PEDOT features desirable characteristics where planar molecular structure ensures process of charge transfer and charge separation. In the investigation of these properties, computational tools emerge as an alternative with low nancial cost when compared to experimental techniques. Knowing that several semi-empirical methodologiess are available and the class of conductive polymers exhibit unique macromolecular characteristics; the objective of this study was to investigate the structural properties of 1-EDOT to 10-EDOT by the latest methodologies available in MOPAC2012 program, that is, PM6, PM7 and RM1. It was found that among them, PM6 methodology provided good results, especially for presenting the planar polymer chain to oligomers of 2-EDOT to 10-EDOT. DFT calculations have been used for organic polymeric systems with conductive characteristics and has evolved as a major computational tools for electronic properties. Thus, for 1-EDOT to 10-EDOT optimized by PM6 methodology, single point calculations were applied using DFT B3LYP/6-31++G(d,p) obtaining information related to the charge transport, especially reducing band-gap energy, border orbital location and formation of an intramolecular charge hall. From these informations, were investigated electrostatic potential map and Density of States (DOS) based on energy levels. In computational analysis of excited states, calculations based on TDDFT using B3LYP/6-31+G were applied to molecular systems, where it was possible to investigate discrete levels of excitation energy in the UV-visible range. In small oligomers of 1-EDOT to 6-EDOT using PM6 optimized structures such calculations showed the possibility of investigating the main configuration related to discrete levels, showing the reduction in energy required for excitation with increasing polymer chain for this material. Having noted both the reduction of energy band-gap and the singlet excitation energy, relatedto increasing polymeric chain, it was investigated these properties for a macromolecular system considering infinite oligomers. In this analysis, linear regression applied to the results of 2-EDOT to 6-EDOT had the lowest band-gap energy. Subsequently, band-gap energy was related to the wavelength of maximum absorption of the singlet excitation energy. It was concluded that it is possible to apply semi-empirical calculations followed by single-pint DFT and TDDFT calculations in the investigation of conductive properties of polymeric materials providing significant results to understand charge transport and the prediction of structural and electronic properties. / A busca por materiais com capacidades condutoras vem ganhando atenção na comunidade científica por suas inúmeras aplicações tecnológicas. Além disso, o entendimento do fenômeno de transporte de carga continua sendo visto como um desafio para a comunidade cientifica. Poli (3,4-etilenodioxitiofeno), PEDOT apresenta caracteristicas condutoras desejáveis porque sua estrutura molecular planar garante que haja o processo de transferência e separação de carga. Na investigação dessa propriedade, ferramentas computacionais surgem como uma alternativa de baixo custo financeiro quando comparados a técnicas experimentais. Sabendo que diversas metodologias semi-empíricas estão disponíveis e que a classe de polímeros condutores apresentam caracteressticas macromoleculares únicas; objetivou-se neste estudo a investigação das propriedades estruturais de 1-EDOT a 10-EDOT pelas mais recentes metodologias disponíveis no programa MOPAC2012, isto é, PM6, PM7 e RM1. Verificou-se que dentre elas, a metodologia PM6 forneceu bons resultados em relação aos resultados experimentais, principalmente por apresentar a cadeia polimérica planar para oligômeros de 2-EDOT a 10-EDOT. Cálculos em DFT tem sido usados para sistemas poliméricos orgânicos com características condutoras e evoluiu como uma das principais ferramentas computacionais para propriedades eletrônicas. Sendo assim, foram aplicados cálculos pontuais em DFT usando B3LYP/6-31++G(d,p)) de 1-EDOT a 10-EDOT a partir de estruturas otimizadas em PM6 obtendo-se informações relevantes ao transporte de carga, principalmente, redução da energia de band-gap, localizaçãoo dos orbitais de fronteiras e formação de um corredor de carga intramolecular. Investigou-se a partir destas informações o mapa de potencial eletrostático e a Densidade de Estados (DOS) por meio dos níveis discretos de energia. Na análise computacional de estados excitados, cálculos baseados em TDDFT usando B3LYP/6-31+G foram aplicados a sistemas moleculares, onde é possível investigar níveis discretos de excitação na faixa do UV-Visível. Nos pequenos oligomeros de 1-EDOT a 6-EDOT, utilizando a estrutura otimizada em PM6, tais cálculos mostraram a possibilidade de investigar as principais configurações de excitação do estado singlete em níveis discretos, mostrando a redução da energia necessária para excitação com o aumento da cadeia polimérica para esse material. Por ter verificado tanto a redução da energia de band-gap quanto da energia de excitação de singlete, e que ambos s~ao relacionados ao aumento da cadeia polimérica, investigou-se a previsão por extrapolação para um sistema macromolecular com infinitos oligômeros. Nessa análise, a regressão linear aplicada aos resultados de 2-EDOT a 6-EDOT apresentou a menor energia de band-gap. Posteriormente, o band-gap foi relacionado ao comprimento de onda máximo da absorção de singlete. Concluiu-se que é possível aplicar cálculos semi-empíricos em conjunto com cálculos pontuais em DFT e TDDFT na investigação de propriedades condutoras de materiais poliméricos proporcionando resultados expressivos para entender o transporte de carga e a prediação de propriedades estruturais e eletrônicas.
7

Hole Transport Materials for Solid-State Mesoscopic Solar Cells

Yang, Lei January 2014 (has links)
The solid-state mesoscopic solar cells (sMSCs) have been developed as a promising alternative technology to the conventional photovoltaics. However, the device performance suffers from the low hole-mobilities and the incomplete pore filling of the hole transport materials (HTMs) into the mesoporous electrodes. A variety of HTMs and different preparation methods have been studied to overcome these limitations. There are two types of sMSCs included in this doctoral thesis, namely solid-state dye-sensitized solar cells (sDSCs) and organometallic halide perovskite based solar cells. Two different types of HTMs, namely the small molecule organic HTM spiro-OMeTAD and the conjugated polymer HTM P3HT, were compared in sDSCs. The photo-induced absorption spectroscopy (PIA) spectra and spectroelectrochemical data suggested that the dye-dye hole conduction occurs in the absence of HTM and appears to be of significant importance to the contribution of hole transport. The PIA measurements and transient absorption spectroscopy (TAS) indicated that the oxidized dye was efficiently regenerated by a small molecule organic HTM TPAA due to its excellent pore filling. The conducting polymer P3HT was employed as a co-HTM to transfer the holes away from TPAA to prohibit the charge carrier recombination and to improve the hole transport. An alternative small molecule organic HTM, MeO-TPD, was found to outperform spiro-OMeTAD in sDSCs due to its more efficient pore filling and higher hole-mobility. Moreover, an initial light soaking treatment was observed to significantly improve the device performance due to a mechanism of Li+ ion migration towards the TiO2 surface. In order to overcome the infiltration difficulty of conducting polymer HTMs, a state-of-the-art method to perform in-situ photoelectrochemical polymerization (PEP) in an aqueous micellar solution of bis-EDOT monomer was developed as an environmental-friendly alternative pathway with scale-up potential for constructing efficient sDSCs with polymer HTMs. Three different types of HTMs, namely DEH, spiro-OMeTAD and P3HT, were used to investigate the influence of HTMs on the charge recombination in CH3NH3PbI3 perovskite based sMSCs. The photovoltage decay measurements indicate that the electron lifetime (τn) of these devices decreases by one order of magnitude in the sequence τspiro-OMeTAD > τP3HT > τDEH.

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