Polímeros quirais conjugados para aplicação em metamateriais

Orientador : Profª. Drª. Leni C. AkcelrudTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Química. Defesa: Curitiba, 14/04/2015Inclui referências : f. 106-113Resumo: Recentemente, o desenvolvimento de meios poliméricos que mimetizam as propriedades chaves dos metamateriais, como por exemplo o índice de refração negativo, tem emergido com alternativa. De maneira geral, a área da fotônica quiral está sendo redefinida pelo avanço das novas classes de materiais poliméricos relativamente flexíveis e de baixo custo, cuja atividade óptica não é acessível aos materiais, ditos naturais. Portanto, estes materiais são uma grande promessa para uso em metafotônica (manipulação de ondas eletromagnéticos por materiais nanoestruturados para controle da propagação de luz). Para aumentar a quiralidade e a atividade óptica associada, os materiais podem ser manipulados de várias maneiras, como por exemplo, a preparação de estruturas auto-montadas e fases colestéricas em cristais líquidos, ao passo que em sistemas poliméricos, estas morfologias podem ser induzidas por interações enantioseletivas com moléculas quirais pequenas ou por indutores de estruturas helicoidais em fibras poliméricas. Neste trabalho foram avaliados cinco novos polímeros conjugados com base em fluoreno quiral: LaPPS61 (homopolímero do fluoreno), LaPPS62 (copolímero contendo quinoxalina), LaPPS63 (copolímero contendo fenileno), LaPPS64 (copolímero contendo bifenileno) e LaPPS65 (copolímero contendo naftaleno). Todos os materiais foram sintetizados e caracterizados estruturalmente, e suas propriedades ópticas no estado sólido foram investigadas com o auxílio de técnicas espectroscópicas de UV-Vis e dicroísmo circular. Além disso, estudos teóricos foram feitos para auxiliar na compreensão dos fenômenos envolvidos e também para propor as conformações topológicas das estruturas helicoidais. Como resultado expressivo, o polímero LaPPS63 apresentou até o momento, o maior valor de parâmetro de quiralidade para materiais não dopados encontrados na literatura. Ademais, foram investigadas cinco propriedades intrínsecas dos polímeros (transição vítrea, massa molar, apertura de hélice, força rotacional e fator de dissimetria) e correlacionadas com o parâmetro de quiralidade, com o intuito de propor modelos a serem seguidos na confecção dos próximos polímeros quirais conjugados. Para a validação dos modelos, um polímero quiral estabelecido pela literatura foi aplicado e os resultados obtidos foram considerados satisfatórios.Abstract: Recently, development of polymeric media mimicking the key properties of metamaterials, such as negative refractive index has emerged. Generally speaking, the whole area of chiral photonics is getting redefined with the advent of novel classes of flexible and low-cost chiral polymeric materials with optical activity non-accessible in materials called naturals. In this way, these materials hold great promise for use in metaphotonics (manipulation of electromagnetic waves in nano-engineered materials to control propagation of light). To enhance the chirality and optical activity associated, these materials can be manipulated in many ways, such as the preparation of self-assembling structures and cholesteric liquid crystals, whereas in polymer systems, these morphologies can be done by enantioselective interactions with small chiral molecules or initiating helical assembly of the polymeric fibrils. In this work, five new polymers based on chiral fluorene were evaluated: LaPPS61 (homopolymer of fluorene), LaPPS62 (copolymer containing quinoxaline), LaPPS63 (copolymer containing phenylene), LaPPS64 (copolymer containing biphenylene) and LaPPS65 (copolymer containing naphthalene). All materials were synthetized and characterized structurally and its optical properties in solid state were investigated using spectroscopy techniques such as, UV-Vis and Circular Dichroism. In addition, theoretical studies were done to assist the understanding phenomena involved and also, to propose topological conformations of helical structures. As an impressive result, the LaPPS63 showed at this moment, the highest chirality parameter for non-doped materials founded in literature. Furthermore, five intrinsic properties of these polymers (glass transition, molar masses, tightness, rotational strength and dissymmetry ratio) were investigated and correlated with chirality parameter, to aim models to be follow for next generations of chiral conjugated polymers. To validate these models, a chiral polymer established in literature was applied and the results were considers satisfactory

Síntese, caracterização e propriedades fotofísicas de Copolímeros contendo unidades Fluoreno, Fenileno e Tiofeno.

Orientadora: Profa. Dra. Leni C. AkcelrudDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduaçao em Engenharia - PIPE. Defesa: Curitiba,24/02/2011Bibliografia: fls. 98-101Área de concentraçao: Engenharia e Ciencia dos MateriaisResumo: Com o objetivo de obter uma visão sobre as relações entre a composição e propriedades opto-eletrônica de polímeros conjugados, três copolímeros foram preparados onde unidades fluoreno foram alternadas com unidades fenileno e tiofeno. A unidade fluoreno foi mantida constante, enquanto que as concentrações das duas outras unidades de repetição variaram de forma sistemática. Estas unidades estão entre as mais utilizadas na engenharia macromolecular dessa classe de polímeros. A composição exata dos materiais foi determinada por RMN de estado sólido utilizando o método CPMAS. Os valores assim obtidos foram muito semelhantes aos previstos teoricamente. O comportamento fotofísico estudado por espectrometria de absorção eletrônica e fluorescência estática e resolvida no tempo, apresentou alterações de acordo com a razão de tiofeno/fenileno, mostrando um deslocamento batocrômico gradual com o aumento do teor de tiofeno. Medidas de decaimento indicaram uma tendência de formação de agregados no estado fundamental ou em formas exciméricas, e também transferência de energia das unidades fluoreno/fenileno para as unidades fluoreno/tiofeno. A eficiência da transferência mostrou-se dependente do teor de tiofeno, mas não de forma linear. Os dispositivos eletroluminescentes demonstraram que o teor de tiofeno não influencia o transporte de carga e a luminescência é prejudicada pela inserção de tiofeno nas cadeias poliméricas. No entanto, como observado na fotoluminescência, houve uma mudança batocrômica gradual com o aumento no teor de tiofeno. As propriedades do copolímero LaPPS30-50, em que o tiofeno está presente em 50% das unidades em relação ao fenileno, mostraram forte desvio da tendência geral observada para os outros materiais, como a menor temperatura de transição vítrea, menor bsortividade molar, menor rendimento quântico e baixo desempenho eletroluminescente.Abstract: Aiming to get insight on the relationships between composition and optoelectronic properties of conjugated polymers, three terpolymers were prepared in which fluorene moieties were alternated with phenylene and thiophene ones. The fluorene content was kept constant whereas the concentration of the the two other repeating units was varied systematically. These units are among the most employed in the macromolecular engineering of these classes of polymers. The exact composition of the materials was determined by solid state NMR using the CPMAS method. The values thus obtained were very close to those forecasts theoretically. The photophysical behavior, studied by electronic absorption spectrometry and static and time resolved photoluminescence showed changes according to the phenylene/thiophene ratio, redshifting gradually with increases in thiophene content. Decay data indicated a tendency to aggregate formation either in ground state or in excimeric forms, and also energy transfer from the fluorene/phenylene units to fluorene/thiophene ones. The efficiency of that transfer showed to be dependent on the thiophene content, not in a linear fashion. The electroluminescence devices showed the thiophene content doesn’t influence the charge transport and luminescence performance is impaired by the inse tion of thiophene in the polymer chains. Nevertheless, as observed in photoluminescence, there was a gradual batochromic shift with increases in thiophene content. The properties of copolymer LaPPS30-50, in which the thiophene was in 50% amount in relation to phenylene showed strong deviation from the general trends observed for the other materials, such as lower glass transition temperature, lower molar absorptivity, lower quantum yield and poor electroluminescence performance

Photo- and electroluminescence in a series of PPV type terpolymers containing fluorene, thiophene and phenylene units

The emissive properties of terpolymers with fluorene, thiophene and phenylene groups, forming alternating PPV type structures, are discussed in terms of their composition, photo- and electroluminescence properties. The fluorene groups were inserted in each phenylene-vinylene and thiophene-vinylene units, and their concentration did not vary, representing 50% of the molar composition. The ratio of thiophene-vinylene/phenylene-vinylene varied in the range 25,50 and 75%. Photo- and electroluminescence properties were strongly dependent on the thiophene-vinylene content and were compared with the fluorene-vinylene-thiophene and fluorene-vinylene-phenylene parent copolymers. (C) 2012 Elsevier B.V. All rights reserved

De-aggregation of a polyfluorene derivative in clay nanocomposites: a photophysical study

The de-aggregation of a very luminescent polyfluorene derivative poly(9,9-di-hexylfluorenediyl divinylene-alt-1,4-phenylenevinylene), which has a high tendency to π-stacking aggregation was achieved through the interaction of the polymer with clay in clay/polymer nanocomposites. The mixing of diluted toluene polymer solutions with kaolinite was enough to promote the de-aggregation, even without the indication of polymer intercalation, indicating that the polymer de-aggregation was obtained due to its interactions with clay platelet surfaces. The photoluminescence observed for the dispersed polymer on clays showed an increase in intensity and a blue-shift of the photoluminescence, when compared with pure pristine material in thin film form. The results presented bring the possibility to produce more efficient polymer based devices and to carry single molecule studies using nanocomposite film formation

LTR Retrotransposons in Fungi

Transposable elements with long terminal direct repeats (LTR TEs) are one of the best studied groups of mobile elements. They are ubiquitous elements present in almost all eukaryotic genomes. Their number and state of conservation can be a highlight of genome dynamics. We searched all published fungal genomes for LTR-containing retrotransposons, including both complete, functional elements and remnant copies. We identified a total of over 66,000 elements, all of which belong to the Ty1/Copia or Ty3/Gypsy superfamilies. Most of the detected Gypsy elements represent Chromoviridae, i.e. they carry a chromodomain in the pol ORF. We analyzed our data from a genome-ecology perspective, looking at the abundance of various types of LTR TEs in individual genomes and at the highest-copy element from each genome. The TE content is very variable among the analyzed genomes. Some genomes are very scarce in LTR TEs (<50 elements), others demonstrate huge expansions (>8000 elements). The data shows that transposon expansions in fungi usually involve an increase both in the copy number of individual elements and in the number of element types. The majority of the highest-copy TEs from all genomes are Ty3/Gypsy transposons. Phylogenetic analysis of these elements suggests that TE expansions have appeared independently of each other, in distant genomes and at different taxonomical levels. We also analyzed the evolutionary relationships between protein domains encoded by the transposon pol ORF and we found that the protease is the fastest evolving domain whereas reverse transcriptase and RNase H evolve much slower and in correlation with each other

Síntese, caracterização e propriedades fotofísicas de Copolímeros contendo unidades Fluoreno, Fenileno e Tiofeno.

Orientadora: Profa. Dra. Leni C. AkcelrudDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduaçao em Engenharia - PIPE. Defesa: Curitiba,24/02/2011Bibliografia: fls. 98-101Área de concentraçao: Engenharia e Ciencia dos MateriaisResumo: Com o objetivo de obter uma visão sobre as relações entre a composição e propriedades opto-eletrônica de polímeros conjugados, três copolímeros foram preparados onde unidades fluoreno foram alternadas com unidades fenileno e tiofeno. A unidade fluoreno foi mantida constante, enquanto que as concentrações das duas outras unidades de repetição variaram de forma sistemática. Estas unidades estão entre as mais utilizadas na engenharia macromolecular dessa classe de polímeros. A composição exata dos materiais foi determinada por RMN de estado sólido utilizando o método CPMAS. Os valores assim obtidos foram muito semelhantes aos previstos teoricamente. O comportamento fotofísico estudado por espectrometria de absorção eletrônica e fluorescência estática e resolvida no tempo, apresentou alterações de acordo com a razão de tiofeno/fenileno, mostrando um deslocamento batocrômico gradual com o aumento do teor de tiofeno. Medidas de decaimento indicaram uma tendência de formação de agregados no estado fundamental ou em formas exciméricas, e também transferência de energia das unidades fluoreno/fenileno para as unidades fluoreno/tiofeno. A eficiência da transferência mostrou-se dependente do teor de tiofeno, mas não de forma linear. Os dispositivos eletroluminescentes demonstraram que o teor de tiofeno não influencia o transporte de carga e a luminescência é prejudicada pela inserção de tiofeno nas cadeias poliméricas. No entanto, como observado na fotoluminescência, houve uma mudança batocrômica gradual com o aumento no teor de tiofeno. As propriedades do copolímero LaPPS30-50, em que o tiofeno está presente em 50% das unidades em relação ao fenileno, mostraram forte desvio da tendência geral observada para os outros materiais, como a menor temperatura de transição vítrea, menor bsortividade molar, menor rendimento quântico e baixo desempenho eletroluminescente.Abstract: Aiming to get insight on the relationships between composition and optoelectronic properties of conjugated polymers, three terpolymers were prepared in which fluorene moieties were alternated with phenylene and thiophene ones. The fluorene content was kept constant whereas the concentration of the the two other repeating units was varied systematically. These units are among the most employed in the macromolecular engineering of these classes of polymers. The exact composition of the materials was determined by solid state NMR using the CPMAS method. The values thus obtained were very close to those forecasts theoretically. The photophysical behavior, studied by electronic absorption spectrometry and static and time resolved photoluminescence showed changes according to the phenylene/thiophene ratio, redshifting gradually with increases in thiophene content. Decay data indicated a tendency to aggregate formation either in ground state or in excimeric forms, and also energy transfer from the fluorene/phenylene units to fluorene/thiophene ones. The efficiency of that transfer showed to be dependent on the thiophene content, not in a linear fashion. The electroluminescence devices showed the thiophene content doesn’t influence the charge transport and luminescence performance is impaired by the inse tion of thiophene in the polymer chains. Nevertheless, as observed in photoluminescence, there was a gradual batochromic shift with increases in thiophene content. The properties of copolymer LaPPS30-50, in which the thiophene was in 50% amount in relation to phenylene showed strong deviation from the general trends observed for the other materials, such as lower glass transition temperature, lower molar absorptivity, lower quantum yield and poor electroluminescence performance

Highly efficient polymer blends from a polyfluorene derivative and PVK for LEDs

The photophysical and electroluminescent properties of blends of a polyfluorene derivative of the PPV type, poly[(9,9-dihexyl-9H-fluorene-2,7-diyl)-1,2-ethenediyl-1,4-phenylene-1,2-ethenediyl] (labeled as LaPPS16) and poly(vinylcarbazole) - PVK are presented and discussed in terms of the operating light emission mechanisms. Static and dynamic fluorescence measurements and morphology data showed a powerful exciton migration from the host (PVK) to the guest (LaPPS16) resulting in emission coming from solely LaPPS16, even when in concentrations small as 1%. Electroluminescence was greatly enhanced with the blending; increases of 18 times in efficiency and 20 times in luminance were achieved in the blend containing 20% LaPPS16, with 3 V applied voltage

Photo- and electroluminescence in a series of PPV type terpolymers containing fluorene, thiophene and phenylene units

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The emissive properties of terpolymers with fluorene, thiophene and phenylene groups, forming alternating PPV type structures, are discussed in terms of their composition, photo- and electroluminescence properties. The fluorene groups were inserted in each phenylene-vinylene and thiophene-vinylene units, and their concentration did not vary, representing 50% of the molar composition. The ratio of thiophene-vinylene/phenylene-vinylene varied in the range 25,50 and 75%. Photo- and electroluminescence properties were strongly dependent on the thiophene-vinylene content and were compared with the fluorene-vinylene-thiophene and fluorene-vinylene-phenylene parent copolymers. (C) 2012 Elsevier B.V. All rights reserved.2377179Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Synthesis and Characterization of a Multifunctional Conjugated Polymer

This work reports the synthesis and characterization of a conjugated polymer based on fluorene and terpyridine, namely, poly[(9,9-bis(3-((S)-2-methylbutylpropanoate))fluorene-alt-6,6′-(2,2′:6′,2′′-terpyridin-6-yl)] (LaPPS71). The structure was characterized by 1H and 13C nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR) spectroscopy. The molar mass was measured by gel permeation chromatography (GPC). As thermal characterization, the glass transition temperature (Tg) was measured by differential scanning calorimetry (DSC). The polymer structure contains two sites capable of complexation with metallic ions, affording the possibility of obtainment of independent or electronically coupled properties, depending on the complexation site. The photophysical properties were fully explored in solution and solid state, presenting ideal results for the preparation of various metallopolymers, in addition to potential application as a metamaterial, due to the presence of the chiral center in the side chains of the polymer

De-aggregation of polyfluorene derivative by blending with a series of poly(alkyl methacrylate)s with varying sidegroup sizes

A polyfluorene derivative of the PPV, poly(9,9`-n-dihexyl-2,7-fluorenedilvinylene-alt-1,4-phenylenevinylene), with a strong tendency to aggregation was blended with several members of a series composed by poly(alkyl methacrylate)s with the following substituents in the ester position: methyl, ethyl, isopropyl, isobutyl, n-butyl, and cyclohexyl. The de-aggregation effect in blends was studied by steady-state photoluminescence spectroscopy using several blend compositions. The efficiency of each dispersing phase was discussed in terms of the polymer miscibility, controlled by interaction parameters between the polyfluorene and every poly(alkyl methacrylate)s, here described using Hilde-brand solubility parameters. (c) 2009 Elsevier Ltd. All rights reserved.FAPESPFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPqCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CAPESFundação AraucáriaFundacao AraucariaMinistério da Ciência, Tecnologia e Inovação do Brasil (MCTI)MCT/IMM