published_or_final_version / Chemistry / Master / Master of Philosophy

O objetivo principal deste trabalho de doutorado foi a confecção de materiais híbridos formados a partir da união de nanopartículas de ouro com o polímero poli(3-hexiltiofeno) (P3HT). Os materiais híbridos foram obtidos através da produção de filmes de Langmuir e Langmuir-Schaefer (LS). Nanopartículas de ouro foram sintetizadas em fase aquosa (NpAu), utilizando o método de Turkevich e também, encapsuladas com 1-Octadecanotiol (NpAuOctatiol), apresentando solubilidade em clorofórmio. As NpAu foram utilizadas na subfase de uma cuba de Langmuir e o P3HT espalhado na interface ar/água. Ao transferir o filme de Langmuir formado para um substrato sólido, na forma de filme de Langmuir-Schaefer (deposição horizontal) foi possível obter um material híbrido contendo NpAu e P3HT. As NpAuOctatiol foram utilizadas para preparação de filmes LS híbridos através do espalhamento de soluções contendo uma mistura de P3HT com NpAuOctatiol com diferentes proporções. A presença das nanopartículas de ouro foi comprovada, principalmente, pelas imagens de MEV-FEG. Os filmes LS do P3HT apresentaram anisotropia ótica, permitindo inferir o tipo de orientação das moléculas tanto nos filmes de Langmuir como LS. A incorporação das nanopartículas de ouro no filme influencia na orientação do P3HT, bem como no processo fotodegradativo. Esses filmes foram utilizados em testes de sensibilidade para vapores de compostos orgânicos e água através de medidas de absorção da luz visível. Os filmes apresentaram sensibilidade apenas para três dos solventes testados: tolueno, THF e clorofórmio. Os filmes de P3HT apresentam comportamento eletrocrômico, e esse efeito pode ser observado através da aplicação de potencial por voltametria cíclica durante o registro do espectro de absorção no visível dos filmes. Comportamento eletrocrômico similar foi observado em todos os filmes LS, os quais apresentaram reversibilidade da cor inicial somente com a passagem do potencial inverso ou após certo tempo, o que não se observou para os filmes spin-coating, que apresentou recuperação da cor imediatamente após o potencial ser interrompido. Esse fato indica que o maior ordenamento dos filmes LS mantém a dopagem do filme por mais tempo, e que a presença das nanopartículas de ouro não altera essa propriedade. / The main aim of this doctorate work was the preparation of hybrid materials formed from the union of gold nanoparticles with the polymer poly (3-hexylthiophene) (P3HT). The hybrid material was obtained through the production of Langmuir and Langmuir-Schaefer (LS) films. Gold nanoparticles were synthesized in aqueous phase (AuNp) using the Turkvich method and encapsulated with 1-Octadecanethiol (AuNpOctathiol) with solubility in chloroform. The AuNp were used in the subphase of a Langmuir trough and the P3HT was spread at the air/water interface. When the Langmuir film was transferred, forming the Langmuir-Schaefer films (horizontal deposition), it was possible to get a hybrid material containing AuNp and P3HT. The AuNpOctathiol were used for the preparation of hybrid LS films through the spreading of a solution containing a mixture of P3HT and AuNpOctathiol with different proportions. The presence of gold nanoparticles has been demonstrated mainly by FEG-SEM images. The LS films of P3HT showed optical anisotropy, allowing to infer the type of orientation of the molecules in both Langmuir and LS films. The incorporation of gold nanoparticle in the film influenced the orientation of P3HT, as well as the process of photodegradation of LS films. These films were used in sensitivity tests for vapor of volatile organic compounds and water through measurements of visible light. The films showed sensitivity only for three of the tested compounds: toluene, THF and chloroform. P3HT films exhibited electrochromic behavior and this effect can be observed by applying potential through cyclic voltammetry during the registration of the absorption in the visible spectrum of the film. A similar Electrochromic behavior was observed in all LS films, showing reversibility of the initial color only with the passage of the reverse potential, or after a certain time. Such behavior was not observed in Spin-coating films, which showed recovery of the color immediately after stopping the potential. This fact indicates not only that greater order of LS films maintains the film doping, but also the presence of gold nanoparticles does not change this property.

O objetivo principal deste trabalho de doutorado foi a confecção de materiais híbridos formados a partir da união de nanopartículas de ouro com o polímero poli(3-hexiltiofeno) (P3HT). Os materiais híbridos foram obtidos através da produção de filmes de Langmuir e Langmuir-Schaefer (LS). Nanopartículas de ouro foram sintetizadas em fase aquosa (NpAu), utilizando o método de Turkevich e também, encapsuladas com 1-Octadecanotiol (NpAuOctatiol), apresentando solubilidade em clorofórmio. As NpAu foram utilizadas na subfase de uma cuba de Langmuir e o P3HT espalhado na interface ar/água. Ao transferir o filme de Langmuir formado para um substrato sólido, na forma de filme de Langmuir-Schaefer (deposição horizontal) foi possível obter um material híbrido contendo NpAu e P3HT. As NpAuOctatiol foram utilizadas para preparação de filmes LS híbridos através do espalhamento de soluções contendo uma mistura de P3HT com NpAuOctatiol com diferentes proporções. A presença das nanopartículas de ouro foi comprovada, principalmente, pelas imagens de MEV-FEG. Os filmes LS do P3HT apresentaram anisotropia ótica, permitindo inferir o tipo de orientação das moléculas tanto nos filmes de Langmuir como LS. A incorporação das nanopartículas de ouro no filme influencia na orientação do P3HT, bem como no processo fotodegradativo. Esses filmes foram utilizados em testes de sensibilidade para vapores de compostos orgânicos e água através de medidas de absorção da luz visível. Os filmes apresentaram sensibilidade apenas para três dos solventes testados: tolueno, THF e clorofórmio. Os filmes de P3HT apresentam comportamento eletrocrômico, e esse efeito pode ser observado através da aplicação de potencial por voltametria cíclica durante o registro do espectro de absorção no visível dos filmes. Comportamento eletrocrômico similar foi observado em todos os filmes LS, os quais apresentaram reversibilidade da cor inicial somente com a passagem do potencial inverso ou após certo tempo, o que não se observou para os filmes spin-coating, que apresentou recuperação da cor imediatamente após o potencial ser interrompido. Esse fato indica que o maior ordenamento dos filmes LS mantém a dopagem do filme por mais tempo, e que a presença das nanopartículas de ouro não altera essa propriedade. / The main aim of this doctorate work was the preparation of hybrid materials formed from the union of gold nanoparticles with the polymer poly (3-hexylthiophene) (P3HT). The hybrid material was obtained through the production of Langmuir and Langmuir-Schaefer (LS) films. Gold nanoparticles were synthesized in aqueous phase (AuNp) using the Turkvich method and encapsulated with 1-Octadecanethiol (AuNpOctathiol) with solubility in chloroform. The AuNp were used in the subphase of a Langmuir trough and the P3HT was spread at the air/water interface. When the Langmuir film was transferred, forming the Langmuir-Schaefer films (horizontal deposition), it was possible to get a hybrid material containing AuNp and P3HT. The AuNpOctathiol were used for the preparation of hybrid LS films through the spreading of a solution containing a mixture of P3HT and AuNpOctathiol with different proportions. The presence of gold nanoparticles has been demonstrated mainly by FEG-SEM images. The LS films of P3HT showed optical anisotropy, allowing to infer the type of orientation of the molecules in both Langmuir and LS films. The incorporation of gold nanoparticle in the film influenced the orientation of P3HT, as well as the process of photodegradation of LS films. These films were used in sensitivity tests for vapor of volatile organic compounds and water through measurements of visible light. The films showed sensitivity only for three of the tested compounds: toluene, THF and chloroform. P3HT films exhibited electrochromic behavior and this effect can be observed by applying potential through cyclic voltammetry during the registration of the absorption in the visible spectrum of the film. A similar Electrochromic behavior was observed in all LS films, showing reversibility of the initial color only with the passage of the reverse potential, or after a certain time. Such behavior was not observed in Spin-coating films, which showed recovery of the color immediately after stopping the potential. This fact indicates not only that greater order of LS films maintains the film doping, but also the presence of gold nanoparticles does not change this property.

Previous studies of the redox states of linear conjugated oligomers as models for polarons and bipolarons in conjugated polymers do not fully address the influence of intermolecular interactions on the electronic structure of conjugated systems in the solid state. Fusion of oligothiophenes onto a bicyclo[4.4.1]undecane core holds the conjugated oligomers in a permanent cofacial stack. One- and two-electron oxidation of the stacked oligomers affords mono(radical cation)s and dications that serve as models for polarons and bipolarons in p-doped conjugated polymers and demonstrates the effect of pi-stacking on the electronic structure of these species. Installation of phenyl-capped and ferrocenyl-capped oligothiophenes allows us to systematically vary pi-stacked oligomers and study intramolecular charge migration in other linear conjugated molecules.

Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references. Also available in print.

Polythiophenes have great potential as semiconductors for use in organic field effect transistors and light emitting diodes. Recent research has been focused on the design, synthesis and characterization of fluorinated polythiophenes and oligothiophenes. Various fluoroalkyl side chains have been introduced to induce polymer self-assembly, to control the electronic properties of the conjugated backbone, and to modify the solubility of the polymer in supercritical CO2. This work led to the preparation of poly(3-(perfluorooctyl)thiophene), which is one of only a few examples of n-dopable polythiophenes, and is the first supercritical CO2-soluble conducting polymer. An alternating copolymer consisting of 3-perfluoroakyl and 3-alkylthiophene units has been synthesized. This polymer, with alternating electron-donating and withdrawing substituents, has a high quantum yield for fluorescence in solution relative to the two homopolymers, and strong fluorescence in solid state. Based on the study on its nanocrystals, the unusual photophyiscs may be due to the formation of the supramolecular structure with hexagonal packing. A novel thiophene monomer, 3-(1,1-difluorooctyl)thiophene, was prepared to further tune the electronic structure of polythiophenes by changing the fluorination pattern of side chains, while retaining solubility in organic solvents by virtue of the hydrocarbon side chain. a-Hexyl-w-perfluorohexylsexithiophene was synthesized to make a novel amphiphilic material for use in TFTs. Models for interchain charge transfer in doped conducting polymers were also developed. Stacked and unstacked conjugated oligomers have been synthesized as models for conducting polymers. The bis(radical cation) form and the dication-neutral form of compounds in which conjugated oligomers are held in a stacked arrangement are shown to coexist and in equilibrium with each other. The coexistence of these two forms further suggests that both may serve as charge carriers. Interconversion between these forms by disproportionation mimics a possible mechanism for charge migration in doped conjugated polymers.

Intrinsically conducting polymers (ICPs) with high mechanical strength and electrical conductivity are attractive for several applications spanning the fields of energy, defense, and transportation. Electrochemically processed polythiophene (PTh) films are a class of ICPs that have been demonstrated recently to possess electrical conductivities as high as 1,300 S/cm and be stronger than common types of processed aluminum foils. While these results are promising, the electrical conductivity of PTh is still low compared to metals and the effects of important process conditions such as electrode resistance, distance between working and counter electrodes, and thiophene concentration on the structure and physical properties of electrochemically processed PTh films must be investigated in detail. In this work, electrode resistance and inter-electrode distance were demonstrated to be inversely proportional to the charge efficiency for PTh film growth. A critical concentration of thiophene that produced films with the highest conductivity was also revealed. Anionic surfactants sodium dodecyl sulfate (SDS) and sodium dodeclybenzene sulfonate (SDBS) were used, with and without a proton scavenger, in the Lewis acid boron trifluoride diethyl etherate (BFEE) electrolyte, which allows polymerization of thiophene at low oxidation potentials, to enhance the ordering and conjugation length of PTh through stabilization of the radical cation of thiophene via the dodecyl chain of the anionic surfactants. X-ray diffraction spectra revealed enhanced order and packing when surfactant was used during the processing of PTh films, and measured electrical conductivities were increased by as much as 300% because of the surfactant-mediated structural improvements. Necking behavior observed in tensile test of PTh films with anionic surfactant additives also suggests chain alignment and increased chain length.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2005. / Morhan Srinivasarao, Committee Member ; CP Wong, Committee Member ; David M. Collard, Committee Chair ; Marcus Weck, Committee Member ; Laren Tolbert, Committee Member.

Orientador: João Sinézio de Carvalho Campos / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-21T06:37:30Z (GMT). No. of bitstreams: 1 Gomes_AlexLinardi_D.pdf: 4308233 bytes, checksum: 4eb5a86fd91e54e1c262eebbc0abe8d1 (MD5) Previous issue date: 2012 / Resumo: As propriedades elétricas apresentadas por alguns polímeros condutores e suas misturas têm contribuído para o avanço tecnológico de diversas áreas como a da medicina e a da microeletrônica. As técnicas de síntese fotoquímica e de obtenção de membranas por deposição em centrífuga tipo spinner usando polímeros de sacrifício têm possibilitado a preparação de misturas poliméricas com boas propriedades condutoras. Este trabalho teve como objetivo preparar misturas poliméricas condutoras de Poli(3-tiofeno acetato de metila)/Poli(butileno succinato) PT3MA/PBS e compósitos de Poli(3-tiofeno acetato de metila)/Poli(fluoreto de vinilideno)/Silicato de zinco dopado com manganês Zn2SiO4:Mn "PT3MA/PVDF/Zn2SiO4:Mn" para obtenção, respectivamente, de membranas ultrafinas biodegradáveis condutoras e filmes aplicáveis a dispositivos eletroluminescentes. Um estudo paralelo sobre as propriedades elétricas das misturas poliméricas obtidas por síntese fotoquímica constituídas por Politiofeno/Poli(fluoreto de Vinilideno) foi realizado para avaliar condutividade dos filmes. Os novos materiais foram caracterizados usando as técnicas de Espectroscopia no Infravermelho por Transformada de Fourier (FTIR), Espectroscopia Raman, Ultravioleta Visível, Ressonância Magnética Nuclear, Perfilometria, Elipsometria, Microscopia Óptica, Microscopia Eletrônica Exploratória, Microscopia de Força Atômica, Difração de Raios-X, Calorimetria Diferencial Exploratória (DSC) e Análises Termogravimétricas (TGA). Os resultados das medidas de condutividade elétrica das membranas ultrafinas biodegradáveis de PT3MA/PBS 80:20 mostram uma condutividade de ~10-4 a ~10-5 S/cm conforme a espessura, valores dentro da faixa de normalidade para politiofenos semicondutores. Os valores de condutividade elétrica apresentadas pelas membranas constituídas pela mistura polimérica Poliânion Poli(tiofeno ácido acético)/Poli(fluoreto de vinilideno) PT3AA-K/PVDF obtida por síntese fotoquímica, apontam um aumento de condutividade de até 10-4 na matriz PVDF. O comportamento óptico-elétrico dos dispositivos monocamadas constituídos por filmes do compósito PT3MA/PVDF/ZnSiO4:Mn foi avaliado por medidas de absorção e emissão em UV-visível e por Curvas Características Tensão x Corrente. As medidas de intensidade de energia luminosa comprovam a capacidade de luminescência do novo material e seu potencial para uso como camada ativa de dispositivos óptico-eletroluminescentes / Abstract: The electrical properties of some conducting polymers and their blends have contributed to the technological advancement in various areas such as medicine and microelectronics. Recently, photochemical synthesis and spinner techniques have been using to prepare polymeric blends with good conducting properties. In this study we report the preparation of conducting polymer blends composed of poly (3-thiophene methyl acetate)/Poly (butylene succinate) PT3MA/PBS and composites of poly (3-thiophene methyl acetate)/Poly (vinylidene fluoride)/manganese doped with zinc silicate "PT3MA/PVDF/Zn2SiO4:Mn" for obtaining, respectively, conducting biodegradable nanomembranes and films applicable to electroluminescent devices. A parallel study on the electrical properties of polymeric blends obtained by photochemical synthesis composes of polythiophene / poly (vinylidene fluoride) was conducted to evaluate the conductivity of the films. The new materials were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, Visible Ultraviolet, Nuclear Resonance Magnetic (1H NMR), Profilometry, Ellipsometry, Optical Microscopy, Scanning Electron Microscopy (MEE), Atomic Force Microscopy (AFM), X-Ray Diffraction, Differential Scanning Calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. The electrical conductivity measurements of the 80:20 PT3MA/PBS biodegradable nanomembranes show conductivity from 10-4 to 10-5 S/cm depending on the thickness, values within the range typical found for semiconducting polythiophenes. The conductivity values shown by the membranes composed of PT3AA-K/PVDF poly (thiophene acetic acid) polyanion/poly (vinylidene fluoride) blends obtained by photochemical synthesis, indicate an increase in conductivity of up to 10-4 at PVDF matrix. The optical electric behavior of the monolayer devices formed by PT3MA/PVDF/ZnSiO4:Mn composite films was monitored by absorption and emission measurements in UV-visible and by (I-V) Characteristic Curves. The luminous energy intensity measurements show the luminescence ability of the new material and its potential for use as active layer in electroluminescent optical devices / Doutorado / Ciencia e Tecnologia de Materiais / Doutor em Engenharia Química

This study expands the role of polythiophenes as an electron donating chromophore within energy harvesting milti-modular donor-acceptor systems. The polythiophene moiety would act as an electron donating spacer group between the donor and acceptor entities, viz., phenothiazine and fulleropyrrolidine, respectively, in the newly synthesized supramolecular triads. The triads 10-{[2,2';5',2"] terthiophene-5-fulleropyrrolidine} phenothiazine and 10-{[2,2'] bithiophene-5-fulleropyrrolidine} phenothiazine were synthesized and characterized through electrochemical and spectroscopic methods to ascertain their structural integrity. the componets of the triads were selected for their established redox parameters. Phenothiazine would act as a secondary donor and would facilitate hole-transfer from the polythiophene primary electron donor, due to its ease of oxidation and yield a long-lived charge separated state. Fulleropyrrolidine would act as an acceptor for ease of reductive capabilities and its ability to hold multiple charges. Finally, occurrence of photoinduced electron transferleading to the anticipated charge separated states is established from advanced transient spectroscopic techniques on these novel supramolecular systems.