Esta tese descreve a fabricação, caracterização e possíveis aplicações de compósitos poliméricos nanoestruturados obtidos pela técnica de automontagem. Três sistemas distintos foram analisados: i) nanocompósitos contendo azopolímeros e azocorantes, ii) nanocompósitos contendo compostos de coordenação macrocíclicos (ftalocianinas), e iii) nanocompósitos contendo materiais do tipo doador-receptor, à base de poli(p-fenileno vinileno) (PPV) e azocorantes. Nos compósitos contendo azobenzeno, exploramos as propriedades de birrefringência e a formação de grades de relevo fotoinduzidas. Dois compostos contendo azobenzeno foram utilizados: um copolímero com cromóforos de azobenzeno ligados covalentemente à cadeia principal (Ma-co-DR13) e um azocorante comercial de baixo peso molecular, Brilliant Yellow (BY). Verificou-se através de experimentos de armazenamento óptico que o tempo de escrita até a saturação é muito maior (cerca de 30 min.) que em filmes de azopolímeros produzidos por outras técnicas como casting, em que este tempo é da ordem de dezenas de segundos. O longo tempo foi atribuído às fortes interações eletrostáticas entre as camadas dos filmes automontados, restringindo o processo de reorientação molecular, necessário à indução da birrefringência. Verificamos também que a presença de água entre as camadas do filme exerce influência significativa sobre o tempo de escrita. O tempo característico de escrita diminui de 8 min. para um filme seco para 2 min. após imersão em água. Este efeito é completamente reversível, ou seja, o tempo característico volta a aumentar se o filme for mantido em dessecador durante alguns dias. Grades de relevo foram inscritas nos filmes de BY e analisadas com micro-espectroscopia Raman. Os resultados mostraram um grau variável de fotodegradação no processo de inscrição das grades, dependendo do policátion ou dos parâmetros de fabricação dos filmes, como o pH das soluções. Qualitativamente, a menor ocorrência de fotodegradação foi observada em filmes de poli(alilamina hidroclorada) (P AH) e BY, preparados em soluções de pH = 10. Para os filmes fabricados com ftalocianina tetrasulfonada de ferro (FeTsPc), a combinação das técnicas de espectroscopia no UV-VIS. e no infavermelho (modos transmissão e reflexão) revelou a existência de ligações não-usuais específicas entre o átomo central de ferro da FeTsPc e os grupos não ionizados (NH2) da PAH, usada como policátion. A existência dessas interações ainda não havia sido relatada na literatura e é devida à estrutura de camadas extremamente finas de PAH e FeTsPc. A espessura média de uma bicamada de PAHlFeTsPc foi estimada em cerca de 10 \'Angstron\'. No terceiro tópico abordado, estudamos o processo de transferência de energia entre camadas automontadas de poli(p-fenileno vinileno) (PPV) e do azocorante BY. A transferência de energia pôde ser controlada não só pela variação da distância entre doador e receptor, mas principalmente pelo foto alinhamento das moléculas do BY (receptor) numa direção perpendicular à direção preferencial de emissão do PPV. Esse fotoalinhamento diminui a transferência de energia entre PPV e BY, resultando em um aumento de até 4 vezes na intensidade da fotoluminescência do filme. / This thesis describes the fabrication and possible applications of layer-by-Iayer (LBL) nanostructured films for three distinct systems comprising i) azopolymers and azodyes, ii) organometallic molecules (phthalocyanines) and iii) luminescent polymers and azodyes. Optically induced birefringence and surface relief gratings (SRGs) were studied in the azobenzene-containing composites, using a side-chain azopolymer (Ma-co-DR13) and a commercially available azodye, viz. Brilliant Yellow (BY). Optical storage experiments showed that the writing time required to induce birefringence (up to the saturation) in LBL films of Ma-co-DR13 is ca. 30 min, which is considerably longer than the times required in cast films of azopolymers (tens of seconds). The long writing time was attributed to the electrostatic interactions between the layers in the LBL film, which preclude photoisomerization or the reorientational processes for the azobenzene molecules.ln addition, entrained water in the films was found to affect the writing time. For example, the characteristic writing time decreases from 8 min. for a dry film to ca.2 min. for a film immersed for some minutes in water. This effect was completely reversible. Surface relief gratings were inscribed on LBL films from BY and analyzed with micro-Raman spectroscopy. The Raman spectra revealed that the process for SRG inscription is not entirely light-driven, with the occurrence of photodegradation. Such photodegradation can be minimized upon the appropriate choice of the polycations as well as the experimental conditions used for film fabrication. The lowest level of photodegradation was observed for films of poly(allylamine hydrochloride) (PAH) and BY fabricated from pH 10 solutions. Organometallic supramolecular composites were built using iron tetrasulfonated phthalocyanine (FeTsPc) and P AH as polycation. The combination of electronic and vibrational spectroscopic techniques showed the presence of unusual specific interactions between the central atom of FeTsPc and non-protonated groups from P AH (NH2). These interactions are believed to occur due to the intimate contact between the materials in the very thin PAH/FeTsPc LBL films, whose thickness was 10 ?Angstron? per bilayer. In the poly(p-fenilene vinylene) (PPV) (donor) and BY (acceptor) system, the resonant energy transfer process was exploited to control luminescence. The quenching in luminescence could be controlled by varying the distance between the PPV and BY layers, similarly to what has been reported in the literature. The novelty in this work, however, was the fine-tuning of luminescence achieved with the photoalignment of the acceptor molecules (BY). For example, the intensity of the photoluminescence increased 4 times upon the photoalignment for 10 min. of the BY chromophores.

O presente trabalho utilizou a técnica de automontagem camada-por-camada para produzir eletrodos híbridos de poli(o-metoxianilina) e nanopartículas de pentóxido de vanádio. Foram obtidos filmes acusticamente rígidos, homogêneos com relação à massa depositada e com crescimento linear com o número de bicamadas depositadas. A caracterização eletroquímica foi realizada por voltametria cíclica, onde esse filme apresentou alta capacidade de intercalação/desintercalação de íons lítio e de forma reversível. A capacidade eletroquímica desse filme foi então comparada com filmes automontados de poli(dialildimetilamônio)/V2O5 e polialilamina/V2O5. O filme de Poli(dialildimetilamônio) apresentou um crescimento irregular com dissolução das nanopartículas, o que resultou em uma capacidade eletroquímica extremamente inferior ao filme de poli(o-metoxianilina). O filme de polialilamina apresentou uma deposição mais eficiente de V2O5 que o filme de poli(o-metoxianilina), entretanto essa maior quantidade de pentóxido de vanádio não refletiu em um aumento da capacidade do eletrodo. Os resultados de espectroscopia de impedância eletroquímica mostram que o filme de polialilamina é significativamente mais resistivo que o filme de poli(o-metoxianilina). Essa diminuição da condutividade, associada ao fato de que a poli(o-metoxianilina) também participa do processo de eletrointercalação, explicam seu melhor desempenho frente a intercalação de lítio. A difusão iônica do lítio nos filmes automontados foi estudada por varredura linear a diferentes velocidades, foi observado que o coeficiente de difusão no filme com polialilamina é uma ordem de grandeza menor que no filme de poli(o-metoxianilina). Por fim, o desempenho eletroquímico do filme de poli(o-metoxianilina)/V2O5 foi comparado no eletrólito composto por um líquido iônico hidrofóbico [bis(trifluorometanosulfonil)imideto de 1-butil-2,3-dimetil-imidazólio] com um solvente orgânico convencional (carbonato de propileno). O eletrodo se mostrou estável no líquido iônico, com maior capacidade específica e menor perda de capacidade. O desempenho superior ao eletrólito convencional está relacionado com a natureza iônica do líquido iônico e com a dissolução do filme em carbonato de propileno. Esses resultados, associados com o fato de que o líquido iônico estudado é compatível com ânodos de lítio metálico, indicam cátodos de poli(o-metoxianilina)/V2O5 em eletrólitos de (bis(trifluorometanosulfonil)imideto de 1-butil-2,3-dimetil-imidazólio podem desenvolver baterias de lítio de alta capacidade, durabilidade e segurança. / The present work used layer-by-layer technique to assemble hybrid electrodes of poly(o-methoxyaniline) and vanadium pentoxide nanoparticles. The film obtained was acoustically rigid, with homogeneous mass deposition and linear growth over the bilayer deposition. The electrochemical characterization was performed by cyclic voltammetry and the film showed high capacity for lithium intercalation and high reversibility in the extraction process. This film\'s capacity was compared with self-assembled poly(diallyldimetylammonium)/V2O5 and polyallylamine/V2O5. In the poly(diallyldimetylammonium) film, dissolution of the nanoparticles was observed, which reflected on a very low electrochemical capacity. The deposition of vanadium pentoxide was more efficient in polyallylamine, but even with a higher amount of V2O5, this electrode presented a smaller electrochemical capacity than poly(o-methoxyaniline)/ V2O5. Electrochemical impedance spectroscopy measurements showed that the film with polyallylamine was much more resistive than the film with poly(o-methoxyaniline). The smaller conductivity and the fact that poly(o-methoxyaniline) also participates in the electroinsertion processes explains the higher performance of poly(o-methoxyaniline)/ V2O5 electrode. Linear sweep experiments with different scan rates were performed to study the chemical diffusion of lithium in the layer-by-layer films. It was observed that the diffusion coefficient in the polyallylamine film is ten times smaller than in the poly(o-methoxyaniline) film. The capacity poly(o-methoxyaniline)/V2O5 electrode was also compared in different electrolytes; a hydrophobic ionic liquid [1-butyl- 2,3-dimethyl-imidazolium bis(trifluoromethanesulfonyl)imide] and an organic solvent (propylene carbonate). In ionic liquid the film was stable, had higher capacity and better cyclability, which is related to the ionic nature of the electrolyte and the fact that in propylene carbonate, dissolution of the film was observed. These results, and the possibility of using metallic lithium as anode in [1-butyl-2,3-dimethyl-imidazolium bis(trifluoromethanesulfonyl)imide], indicates the feasibility of using ionic liquids and poly(o-methoxyaniline)/V2O5 cathodes in safe, durable and high performance lithium batteries.

Nanotubos de carbono (CNTs) têm se mostrado versáteis para melhorar propriedades de outros materiais. A integração de CNTs com materiais biológicos, por exemplo, permite obter biossensores com propriedades e sensibilidade otimizadas. Com a manipulação de CNTs em filmes nanoestruturados, pode-se formar nanocompósitos híbridos, cuja interação sinérgica requer métodos experimentais com controle da arquitetura molecular. Neste estudo, utilizamos a técnica de automontagem para obter dois tipos de sensores incorporando CNTs. No primeiro, filmes automontados de CNTs de parede múltiplas (MWNTs) dispersos em poliamidoamina (PAMAM) e alternados com ftalocianina tetrassulfonada de níquel (NiTsPc) foram usados como sensores amperométricos para detectar o neurotransmissor dopamina. As propriedades eletroquímicas obtidas com voltametria cíclica indicaram que a incorporação de MWNTs no filme PAMAM-NT/NiTsPc eleva a corrente de pico redox em três vezes e diminui em 50 mV o potencial de oxidação da dopamina. Isso permitiu detectar dopamina na presença de um interferente típico, o ácido ascórbico. Os sensores apresentaram limite de detecção de 0,5 mol L-1 e alta estabilidade. No segundo, filmes nanoestruturados de PAMAM com nanotubos de carbono de parede única (SWNTs), funcionalizados com grupos carboxílicos, foram fabricados sobre dispositivos de efeito de campo do tipo electrolyte-insulator-semiconductor (EIS) e light-addressable potentiometric sensors (LAPS). Estes dispositivos modificados foram usados em biossensores de penicilina G, após imobilização da enzima penicilinase. A morfologia do filme PAMAM/SWNT era típica de uma estrutura porosa, com grande área superficial, apropriada para adsorção da enzima e facilitar a penetração de íons H+ no filme. Esses biossensores exibiram alta sensibilidade ao pH de 55-58 mV/pH e propriedades melhoradas para a detecção de penicilina G, com sensibilidade de 100 mV/década e melhor desempenho com menor tempo de resposta e sinal mais estável. / Carbon nanotubes (CNTs) are versatile in enhancing the properties of other materials. They can be integrated with biological materials, for instance, in the fabrication of biosensors with optimized sensitivity and performance. With manipulation of CNTs in nanostructured films, one may form hybrid nanocomposites whose synergistic interaction requires experimental methods with control of molecular architecture. In this study, we used the layer-by-layer (LbL) technique to obtain two types of sensors incorporating CNTs. In the first, LbL films of multi-walled carbon nanotubes (MWNTs) dispersed in polyamidoamine (PAMAM) dendrimers and alternated with nickel phthalocyanine (NiTsPc) layers were used in the amperometric detection of the neutransmitter dopamine. The electrochemical properties obtained with cyclic voltammetry indicated that the incorporation of MWNTs in the PAMAM-NT/NiTsPc led to a 3-fold increase in the peak current, in addition to a decrease of 50 mV in the oxidation potential of dopamine. The latter permitted the detection of dopamine even in the presence of a typical interferent, the ascorbic acid. These sensors exhibited a limit of detection of ca. 0.5 mol L-1 and high stability. In the second type, LbL films of PAMAM and single-walled carbon nanotubes (SWNTs), functionalized with carboxylic groups, were deposited on field-effect devices, using electrolyte-insulator-semiconductor (EIS) and light-addressable potentiometric sensors (LAPS). These modified devices were employed as biosensors to detect penicillin G, after immobilizing the enzyme penicillinase. The PAMAM/SWNT film exhibited a highly porous morphology with large surface area, being suitable for enzyme adsorption, in addition to facilitating the penetration of H+ ions through the film. Such biosensors had a high pH sensitivity of ca. 55-58 mV/pH and improved properties toward penicillin G, with sensitivity of 100 mV/decade and enhanced performance, with faster response time and higher stability.

Orientadores: Ana Flávia Nogueira, Valtencir Zucolotto / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-22T02:59:18Z (GMT). No. of bitstreams: 1 Almeida_LuizCarlosPimentel_D.pdf: 6880507 bytes, checksum: f7a2c24853f25411226ae9b66a2de97b (MD5) Previous issue date: 2012 / Resumo: Neste trabalho foram estudados filmes finos multicamadas baseados em polímeros condutores, nanotubos de carbono e um derivado de fulereno. Esses filmes foram depositados pela técnica de deposição camada por camada (LbL) via interações eletrostáticas. Esse trabalho está dividido em duas partes: 1-) Filmes LbL baseados no polímero conjugado poli(p-fenilenovinileno) (PPV) e nanotubos de carbono de parede única funcionalizados com grupos carboxílicos (SWNTCOOH) foram preparados em arquitetura de bloco, caracterizados e aplicados como fotoeletrodos em células solares fotoeletroquímicas. A morfologia desses filmes foi avaliada por microscopia de força atômica (AFM) e de epifluorescência, as quais indicaram uma variação morfológica significativa dos filmes após adição de camadas de nanotubos de carbono. A transferência de carga fotoinduzida do polímero condutor PPV para o SWNT-COOH foi analisada por supressão de fotoluminescência (PL). A caracterização fotoeletroquímica foi realizada sob irradiação de luz branca e os fotoeletrodos contendo SWNT-COOH apresentaram valores de fotocorrente de até 7,5 mA cm. A fotocorrente aumentou e tornou-se mais estável quando uma camada do polímero poli(3,4-etilenodioxitiofeno) dopado com poli(4-sulfonato de estireno) (PEDOT:PSS) foi depositada entre o eletrodo ITO e o filme LbL. 2-) Foram preparados filmes LbL baseados no polímero conjugado poli[2-(3-tienil)-etoxi-4-butilsulfonato] de sódio (PTEBS) e no derivado de fulereno C60-F. A caracterizacao fotofísica mostrou a ocorrência de transferência fotoinduzida de carga do PTEBS para o C60-F, a qual foi também demonstrada por meio da geração de fotocorrente obtida quando os filmes (PTEBS/C60-F) foram aplicados como fotoeletrodos em células solares fotoeletroquímicas. Os resultados obtidos fazem dos filmes LbL baseados em semicondutores orgânicos candidatos promissores para conversão de energia solar. / Abstract: In this work, multilayer thin films based on conducting polymers, carbon nanotubes and fullerene derivatives were studied. These films were fabricated by layer-by-layer deposition technique (LbL) through electrostatic interactions. This work is divided in two parts: 1-) LbL films composed of a conducting polymer poly(p-phenylenevinylene) (PPV) and carboxylic acid functionalized singlewalled carbon nanotubes (SWNT-COOH) were prepared in a block architecture, characterized and applied as electrodes in photoelectrochemical solar cells. Film morphology was evaluated by atomic force and epifluorescence microscopies, showing remarkable changes after incorporation of SWNT-COOH layers. The photoinduced charge transfer from the conducting polymer to SWNT-COOH was analyzed by photoluminescence (PL) quenching. Photoelectrochemical characterization was performed under white light and the films containing SWNTCOOH displayed photocurrent values up to 7.5 mA cm. Photocurrent generation was enhanced and became more stable when an intermediate layer of poly(3,4- ethylenedioxythiophene)¿poly(4-styrenesulfonic acid) (PEDOT:PSS) was interposed between the ITO electrode and LbL films. 2-) LbL films based on the conducting polymer sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate] (PTEBS) and fullerene derivative C60-F were fabricated. Photophysical characterization shows the occurrence of photoinduced charge transfer from PTEBS to C60-F, which was also demonstrated by photocurrent generation obtained when (PTEBS/C60-F) multilayer films were applied as electrodes of photoelectrochemical solar cells. All these results make the LbL films based on organic semiconductors promising canditates towards solar energy conversion. / Doutorado / Físico-Química / Doutor em Ciências

L'adsorption de protéine sur une surface artificielle solide est un phénomène fondamental qui détermine la réponse biologique d'un organisme vivant entrant dans n'importe quel matériel d'implant. Donc, l'adaptation de surfaces pour l'adsorption de protéine contrôlée est au coeur de beaucoup de champs de recherche d'aujourd'hui incluant la science de matériels et la biotechnologie. Dans ce contexte, les matériels sensibles de stimulus qui peuvent changer leurs propriétés comme une réponse à une petite monnaie dans leur environnement physicochimique attirent un grand intérêt comme ils permettent la création de surfaces avec des propriétés commutables pour le contrôle d'adsorption de protéine. Dans cette thèse, nous faisons un rapport sur la conception et l'élaboration de films minces sensibles de stimulus multi et de nanotubes. À cette fin, nous avons employé la couche-par-couche robuste et polyvalente… / Protein adsorption on a solid artificial surface is a fundamental phenomenon that determines the biological response of a living organism entering any implant material. Therefore, tailoring surfaces for controlled protein adsorption is at the heart of many of today's research fields including biotechnology and materials science. In this context, stimuli-responsive materials that are able to change their properties as a response to a small change in their physico-chemical environment are attracting a great interest as they allow the creation of surfaces with switchable properties for the control of protein adsorption. In this thesis, we report on the design and elaboration of multi stimuli-responsive thin films and nanotubes. For this purpose, we employed the robust and versatile layer-by-layer (LbL) assembly technique to incorporate block copolymers made of poly(acrylic acid) PAA and poly(N-isopropylacrylamide) PNIPAM with tunable and well-controlled block lengths. The combination of ellipsometry, quartz crystal microbalance with dissipation monitoring (QCM-D), surface plasmon resonance (SPR) and infrared data reveal the possibility to build up (PAH/PAA-b-PNIPAM)n multilayers. The stimuli-responsive properties of these LbL films were examined by monitoring the adsorption of proteins by means of QCM-D and fluorescence measurements, while varying (i) temperature, (ii) pH, (iii) ionic strength, or (iv) a combination of the above parameters. It appears that all these stimuli strongly influence the amount of adsorbed proteins. In short, these new PNIPAM block copolymer-based LbL coatings are easy to build on substrates of various nature and geometry (including nanoporous membranes).

Orientador: Varlei Rodrigues / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-31T16:45:14Z (GMT). No. of bitstreams: 1 Ferreira_RafaelCintraHensel_M.pdf: 43759995 bytes, checksum: 8636f117e63053d6b540d65b95c34072 (MD5) Previous issue date: 2016 / Resumo: Os filmes orgânicos ultrafinos tem permitido funcionalizar superfícies a fim de introduzir propriedades específicas que diferem daquelas apresentadas em escala macroscópica. Um processo versátil para modificar superfícies e criar sistemas multifuncionais é a técnica de automontagem por adsorção física (LbL, do inglês Layer-by-Layer), na qual nanoestruturas são formadas devido a adsorção de moléculas com cargas opostas em arquiteturas moleculares multicamadas. O monitoramento elétrico do crescimento dos filmes é essencial em experimentos nos quais não são permitidas caracterizações ópticas. Além disto, é importante compreender as propriedades elétricas destes filmes devido a sua utilização em sensores capacitivos para análise química. Deste modo, neste trabalho desenvolvemos um equipamento capaz de acompanhar o crescimento de filmes LbL por meio de medidas de capacitância após a deposição de cada camada de polieletrólitos sobre eletrodos interdigitados (IDEs, do inglês Interdigitated Electrodes). Observamos um aumento linear da capacitância devido ao acúmulo de material dielétrico sobre os IDEs, com uma alternância na medida de capacitância de acordo com o polieletrólito depositado, isto é, há uma reversão de carga na camada mais externa quando a adsorção do policátion é compensada pela do poliânion, ou vice-versa. Utilizando o modelo para o potencial eletrostático de um IDE proposto por M. W. Den Otter, desenvolvemos uma nova metodologia para investigar a constante dielétrica da estrutura multicamadas formada. Obtivemos (16 ± 1) para a constante dielétrica do filme LbL (PDDA/CuTsPc), e (21 ± 3) para a arquitetura (PDDA/PSS), ambos em satisfatória concordância com a literatura. Ademais, desenvolvemos um modelo para interpretar o deslocamento na capacitância medida após a adsorção do policátion a fim de determinar sua densidade de carga superficial, que diminuiu de (0,23 ± 0,02) e/µm2 para (0,08 ± 0,01) e/µm2 quando o PDDA (policátion fortemente carregado) foi substituído pelo PAH (policátion fracamente carregado) para ambos os poliânions analisados. Portanto, desenvolvemos um equipamento para monitorar o crescimento de filmes LbL e uma metodologia que permite obter informações sobre o comportamento dielétrico dos filmes a cada camada depositada, o que pode auxiliar na escolha dos materiais e espessura dos filmes LbL utilizados como elementos transdutores em desenvolvimentos futuros / Abstract: Organic ultrathin films have enabled surface¿s functionalization in order to introduce specific properties which differ from those in macroscopic scale. A versatile process to modify surfaces and create multifunctional systems is the layer-by-layer (LbL) technique, in which the nanostructures are formed due to the adsorption of charged molecules in multilayered molecular architectures. The electrical monitoring of the film's growth is essential in experiments in which optical characterizations can not be used. Moreover, it is important to comprehend the electrical properties of these films owing to their application on capacitive sensors for chemical analysis. In this research we developed a home-made setup to keep track of the LbL film¿s growth by measuring the capacitance after each deposited layer onto interdigitated electrodes (IDEs). We have observed a linear increase in the capacitance due to accumulated dielectric material onto the IDEs, along with an alternation in the measured capacitance according to the deposited polyelectrolyte, i.e., a charge reversal of the outermost layer as the polycation adsorption is compensated by the polyanion adsorption, or vice-versa. Using the IDEs electrostatic potential model proposed by M. W. Den Otter, we have developed a new methodology to investigate the dielectric constant of the formed multilayered structure. A dielectric constant of (16 ± 1) was obtained for (PDDA/CuTsPc) films and (21 ± 3) for (PDDA/PSS) architecture, both in satisfactory agreement with the literature. Furthermore, we have developed a model to interpret the capacitance measurement shift after the polycation adsoption in order to investigate its surface charge density, which decreased from (0.23 ± 0.02) e/µm2 to (0.08 ± 0.01) e/µm2 when PDDA (strong polycation) was replaced by PAH (weak polycation) for both analyzed polyanions. Therefore, we have developed an equipment to monitor the LbL film's growth as well as a methodology that enables the obtaining of information about the film dielectric behavior at each deposited layer, which can assist in the choice of the materials and thickness of the LbL films that are used as transductor elements in future developments / Mestrado / Física / Mestre em Física / 147530/2014 / CNPQ

Nanotubos de carbono (CNTs) têm se mostrado versáteis para melhorar propriedades de outros materiais. A integração de CNTs com materiais biológicos, por exemplo, permite obter biossensores com propriedades e sensibilidade otimizadas. Com a manipulação de CNTs em filmes nanoestruturados, pode-se formar nanocompósitos híbridos, cuja interação sinérgica requer métodos experimentais com controle da arquitetura molecular. Neste estudo, utilizamos a técnica de automontagem para obter dois tipos de sensores incorporando CNTs. No primeiro, filmes automontados de CNTs de parede múltiplas (MWNTs) dispersos em poliamidoamina (PAMAM) e alternados com ftalocianina tetrassulfonada de níquel (NiTsPc) foram usados como sensores amperométricos para detectar o neurotransmissor dopamina. As propriedades eletroquímicas obtidas com voltametria cíclica indicaram que a incorporação de MWNTs no filme PAMAM-NT/NiTsPc eleva a corrente de pico redox em três vezes e diminui em 50 mV o potencial de oxidação da dopamina. Isso permitiu detectar dopamina na presença de um interferente típico, o ácido ascórbico. Os sensores apresentaram limite de detecção de 0,5 mol L-1 e alta estabilidade. No segundo, filmes nanoestruturados de PAMAM com nanotubos de carbono de parede única (SWNTs), funcionalizados com grupos carboxílicos, foram fabricados sobre dispositivos de efeito de campo do tipo electrolyte-insulator-semiconductor (EIS) e light-addressable potentiometric sensors (LAPS). Estes dispositivos modificados foram usados em biossensores de penicilina G, após imobilização da enzima penicilinase. A morfologia do filme PAMAM/SWNT era típica de uma estrutura porosa, com grande área superficial, apropriada para adsorção da enzima e facilitar a penetração de íons H+ no filme. Esses biossensores exibiram alta sensibilidade ao pH de 55-58 mV/pH e propriedades melhoradas para a detecção de penicilina G, com sensibilidade de 100 mV/década e melhor desempenho com menor tempo de resposta e sinal mais estável. / Carbon nanotubes (CNTs) are versatile in enhancing the properties of other materials. They can be integrated with biological materials, for instance, in the fabrication of biosensors with optimized sensitivity and performance. With manipulation of CNTs in nanostructured films, one may form hybrid nanocomposites whose synergistic interaction requires experimental methods with control of molecular architecture. In this study, we used the layer-by-layer (LbL) technique to obtain two types of sensors incorporating CNTs. In the first, LbL films of multi-walled carbon nanotubes (MWNTs) dispersed in polyamidoamine (PAMAM) dendrimers and alternated with nickel phthalocyanine (NiTsPc) layers were used in the amperometric detection of the neutransmitter dopamine. The electrochemical properties obtained with cyclic voltammetry indicated that the incorporation of MWNTs in the PAMAM-NT/NiTsPc led to a 3-fold increase in the peak current, in addition to a decrease of 50 mV in the oxidation potential of dopamine. The latter permitted the detection of dopamine even in the presence of a typical interferent, the ascorbic acid. These sensors exhibited a limit of detection of ca. 0.5 mol L-1 and high stability. In the second type, LbL films of PAMAM and single-walled carbon nanotubes (SWNTs), functionalized with carboxylic groups, were deposited on field-effect devices, using electrolyte-insulator-semiconductor (EIS) and light-addressable potentiometric sensors (LAPS). These modified devices were employed as biosensors to detect penicillin G, after immobilizing the enzyme penicillinase. The PAMAM/SWNT film exhibited a highly porous morphology with large surface area, being suitable for enzyme adsorption, in addition to facilitating the penetration of H+ ions through the film. Such biosensors had a high pH sensitivity of ca. 55-58 mV/pH and improved properties toward penicillin G, with sensitivity of 100 mV/decade and enhanced performance, with faster response time and higher stability.

This work describes the modeling, synthesis, integration and characterization of a novel nanostructure embedded thermoresponsive material for microfluidic applications. The innumerable applications of thermoresponsive surfaces in the recent years have necessitated the development of a rigorous mathematical treatment for these surfaces to understand and improve their behavior. An analytical model is proposed to describe the transfer characteristic (variation of contact angle versus temperature) of a unique switchable, nanostructured, thermoresponsive surface consisting of silica nanoparticles and the thermoresponsive polymer, Poly(N-isopropylacrylamide ) (PNIPAAm) which changes its wetting angle upon heating. Important metrics such as the absolute lower critical solution temperature, threshold & saturation temperatures and gain are modeled and quantified by mathematical expressions. Based on the modeling, a heat source for the thermoresponsive surface was integrated on the glass substrate itself to create a fully functional smart surface. The design and fabrication of a smart platform consisting of the switchable, nanostructured, thermoresponsive surface with an integrated gold microheater for wettability control and its time response analysis was conducted. The insight gained into the behavior of the thermoresponsive surface by using the analytical model, aided the effort in the effective integration of the surface into a microfluidic channel for flow regulation applications. The implementations of novel microfluidic flow regulator concepts were tested. The aim is to integrate a regulator function to a channel surface utilizing the layer-by-layer (LBL) deposition technique. The characterization and pressure differential study of the microfluidic regulators was carried out on simple straight microchannels which were selectively coated with the thermoresponsive surface. Theoretical and experimental studies were performed to determine the important characteristic parameters including capillary, Weber and Reynolds numbers. The pressure differential data was used to develop critical operating specifications. This work lays out a new microfluidic device concept consisting of a channel with a built-in regulatory function.

The present work aims at finding suitable mineral-bonded strengthening layers to protect steel-reinforced concrete (RC) structures from impact events. The strengthening layers are applied to the impact-facing side and absorb large parts of the impact energy. In this way, they protect the RC structures from the impact events. The multilayered strengthening layers consist of a cover layer and a damping layer. The cover layers possess a high strength and a high modulus of elasticity. The impactor directly hits the cover layer, which spreads the impact force to larger areas of the damping layer below. The strengths and moduli of elasticity of the damping layers are minor, and they absorb impact energy, converting it into friction, heat, or potential energy. Several materials have been tested as damping layers, including a concrete mixed with waste tire rubber aggregates, two types of lightweight concrete, and two types of infra-lightweight concrete. The cover layers tested include carbon-fiber-reinforced concrete and various short-fiber-reinforced concretes, some of which are reinforced with 3D hybrid pyramidal truss reinforcing structures. At first, the dynamic material properties were determined with the help of a tensile and a compressive split Hopkinson bar. The small-scale experiments serve to investigate the dynamic material behavior. At the same time, they are the basis for an eventual later numerical analysis of the strengthening layers. A numerical analysis enables the variation of the material parameters. Lastly, large-scale tests with RC cuboids that were fully supported were performed. A choice of cover and damping layer materials was compared to unstrengthened RC cuboids. The first set of experiments strived to vary the damping layer to find the most suitable one that absorbs the highest amount of incident energy, thus minimizing the damage to the RC cuboid. Afterward, the best damping layer material was combined with different cover layers to figure out the best cover layer option.:Abstract i Kurzfassung iii List of Symbols xv List of Abbreviations xix 1 Objectives, Working Program, and Structure 1 1.1 Motivation 1 1.2 Overall Objectives 1 1.3 Working Program 1 2 State of the Art and Theoretical Background 3 2.1 Impact on Structural Elements 3 2.1.1 Soft and Hard Impact 3 2.1.2 Failure Modes Under Hard Impact Conditions 3 2.1.3 Large-Scale Impact Experiments 4 2.1.4 Impact Protection Layers 4 2.2 Introduction of Impact Protection Principles 4 2.2.1 Impact Protection in Nature 4 2.2.2 Technical Impact Protection Examples 9 2.2.3 Summary of Impact Protection Principles and Usable Materials 14 2.3 Mineral-Bonded Damping Layer Materials 15 2.3.1 Waste Tire Rubber Concrete 15 2.3.2 All-Lightweight Aggregate Concrete 16 2.3.3 Infra-Lightweight Concrete 17 2.4 Mineral-Bonded Cover Layer Materials 18 2.4.1 Strain-Hardening Cementitous Composites 18 2.4.2 Textile Reinforced Concrete 19 2.4.3 Hybrid-Fiber Reinforced Concrete 19 2.5 Bond Between Different Strengthening Layers 20 3 Materials under Investigation 21 3.1 Specimen Preparation 21 3.2 Damping Layer Materials 22 3.2.1 Waste Tire Rubber Concrete (WTRC) 22 3.2.2 All-Lightweight Aggregate Concrete With Liapor Aggregates (ALWAC-L) 23 3.2.3 All-Lightweight Aggregate Concrete With Ulopor Aggregates (ALWAC-U) 23 3.2.4 Porous Lightweight Concrete (PLC) 23 3.2.5 Infra-Lightweight Concrete (ILC) 23 3.2.6 Comparison of the Damping Layer Materials 24 3.3 Cover Layer Materials 27 3.3.1 Pagel TF10 CARBOrefit With Carbon Textile Reinforcement (P-C) 27 3.3.2 Strain-Hardening Limestone Calcined Clay Cement (SHLC3) 27 3.3.3 Comparison of the Cover Layer Materials 28 3.4 Partially Loaded Areas 30 4 Methodology of Split Hopkinson Bar Experiments 35 4.1 Experimental Setup and Methodology 35 4.1.1 Compressive Split Hopkinson Bar 35 4.1.2 Tensile Split Hopkinson Bar 36 4.1.3 Instrumentation 39 4.2 Evaluation Process 39 4.2.1 Impedance 40 4.2.2 Raw Data Analysis, Filtering, and Time-Shifting of Pulses 41 4.2.3 Stresses and Strains 42 4.2.4 Deformations 50 4.2.5 Forces and Impulses 51 4.2.6 Energy Absorption 52 4.2.7 Fracture Energy 53 4.2.8 Averaging of the Results 54 5 Compressive Split Hopkinson Bar Experiments 57 5.1 Failure Modes 57 5.2 Stresses and Strains 58 5.2.1 Dynamic Compressive Strength 58 5.2.2 DIF 59 5.3 Deformations 60 5.4 Forces and Impulses 61 5.4.1 Relative Transmitted Force 61 5.4.2 Impulse Transmission 63 5.4.3 Reduction of the Pulse Inclination 64 5.5 Energy Absorption 64 5.6 Conclusions 66 6 Tensile Split Hopkinson Bar Experiments 69 6.1 Failure Modes 69 6.2 Stresses and Strains 70 6.2.1 Dynamic Tensile Strength 70 6.2.2 DIF 71 6.3 Deformations 72 6.4 Forces and Impulses 73 6.4.1 Relative Transmitted Force 73 6.4.2 Impulse Transmission 74 6.4.3 Reduction of the Pulse Inclination 75 6.5 Energy Absorption 75 6.6 Fracture Energy 77 6.7 Conclusions 78 7 Methodology of Cuboid Experiments 79 7.1 Experimental Program 79 7.1.1 Specimen Dimensions and Experimental Setup 79 7.1.2 Experimental Scheme 81 7.2 Measurements Taken During the Experiments 83 7.2.1 Light Barriers 84 7.2.2 Resistor 84 7.2.3 Strain Gauges 84 7.2.4 Laser Doppler Vibrometer 85 7.2.5 Accelerometers 85 7.2.6 Load Cells 85 7.2.7 High-Speed Cameras and DIC 85 7.3 Measurements Taken Before and After the Experiments 86 7.3.1 Impactor Indentation 86 7.3.2 Burst Mass 86 7.3.3 Ultrasonic Pulse Velocity Measurements 86 7.3.4 Stimulation 87 7.4 Evaluation Process 88 7.4.1 Fracture and Damage Process 88 7.4.2 Impactor Velocity, Deceleration, Force, Stress, and Stress Rate 88 7.4.3 Impactor Indentation, Strain, and Strain Rate 90 7.4.4 Vertical Cuboid Deformation, Velocity, and Acceleration 92 7.4.5 Lateral Cuboid Deformation, Velocity, and Acceleration 93 7.4.6 Relative Cuboid Elongation in X- and Y-Direction 93 7.4.7 Strain Measurements on the Reinforcement Bars 94 7.4.8 Path and Derivative of the Support Forces 95 7.4.9 Burst Mass 96 7.4.10 Ultrasonic Pulse Velocity Measurements 96 7.4.11 Stimulation 97 7.4.12 Impulse and Momentum Conservation 99 7.4.13 Energy Conservation 100 7.4.14 Estimation of the Eigenfrequency of the Cuboids 101 8 Damping Layer Variation in Cuboid Experiments 103 8.1 Fracture and Damage Process 103 8.2 Impactor Velocity, Deceleration, and Force 105 8.3 Impactor Indentation 108 8.4 Vertical Cuboid Deformation, Velocity, and Acceleration 110 8.5 Lateral Cuboid Deformation, Velocity, and Acceleration 113 8.6 Relative Cuboid Elongation in X- and Y-Direction 115 8.7 Path and Derivative of the Support Forces 118 8.8 Ultrasonic Pulse Velocity Measurements 120 8.9 Stimulation With the Impulse Hammer 121 8.10 Stimulation With the Steel Impactor 124 8.11 Overview Over Forces, Stresses, Strains, and Their Rates 128 8.12 Impulse and Momentum Conservation 133 8.13 Energy Conservation 135 8.14 Dimensioning of the Required Damping Layer Thickness Depending on the Loading Velocity 136 8.15 Conclusions 137 9 Cover Layer Variation in Cuboid Experiments 139 9.1 Fracture and Damage Process 139 9.2 Impactor Velocity, Deceleration, and Force 141 9.3 Impactor Indentation 144 9.4 Vertical Cuboid Deformation, Velocity, and Acceleration 145 9.5 Lateral Cuboid Deformation, Velocity, and Acceleration 147 9.6 Relative Cuboid Elongation in X- and Y-Direction 149 9.7 Path and Derivative of the Support Forces 150 9.8 Ultrasonic Pulse Velocity Measurements 152 9.9 Stimulation With the Impulse Hammer 153 9.10 Stimulation With the Steel Impactor 155 9.11 Overview Over Forces, Stresses, Strains, and Their Rates 157 9.12 Impulse and Momentum Conservation 162 9.13 Energy Conservation 163 9.14 Conclusions 164 10 Conclusions of the Cuboid Experiments 167 10.1 Main Findings 167 10.2 Most Relevant Sensor Positions and Measurements 167 10.2.1 Digital Image Correlation (DIC) of the Impactor 167 10.2.2 Lateral Acceleration 167 10.2.3 Digital Image Correlation (DIC) of the RC Cuboid 168 10.2.4 Ultrasonic Pulse Velocity (UPV) Measurements 168 10.2.5 Stimulation With the Impulse Hammer and the Steel Impactor 168 10.3 Suggested Improvements to the Setup 168 10.3.1 High-Speed Cameras (HSC) 168 10.3.2 Acceleration Sensors 169 10.3.3 Support Forces 169 10.3.4 Strain Gauges 169 10.3.5 Temperature Sensors 169 10.4 Comparison of the Material Behavior in Compressive SHB and Cuboid Experiments 169 10.4.1 Scattering of Measured Values 169 10.4.2 Failure Modes 170 10.4.3 Loading and Strain Rates 170 10.4.4 Influences of Inertia 170 10.4.5 Forces and Stresses 171 10.4.6 Energy Absorption 171 11 Summary and Conclusions 173 11.1 Compressive SHB Experiments 173 11.2 Tensile SHB Experiments 173 11.3 Damping Layer Variation in Cuboid Experiments 174 11.4 Cover Layer Variation in Cuboid Experiments 174 11.5 Conclusions 175 12 Outlook 177 12.1 Split Hopkinson Bar Testing 177 12.2 Strengthening Procedure 177 12.3 Large-Scale Impact Testing 177 12.4 Design 178 Bibliography 179 List of Figures 193 List of Tables 199 / Die vorliegende Arbeit beschäftigt sich mit der Verstärkung von Stahlbetonbauteilen gegen Impaktbeanspruchungen. Es wurden mineralisch gebundene Verstärkungsschichten entwickelt, die auf der impaktzugewandten Seite aufgebracht wurden und große Teile der Impaktenergie umwandelten, um somit die darunterliegenden Bauteile zu schützen. Die Verstärkungsschichten sind mehrlagig aufgebaut und die Materialien werden in Deck- und Dämpfungsschichten unterschieden. Dabei sind die Deckschichtmaterialien solche, die eine große Festigkeit und Steifigkeit besitzen. Sie werden direkt durch den Impaktor getroffen und sollen die Impaktlast auf einen größeren Bereich der darunterliegenden Dämpfungsschichten verteilen. Die Dämpfungsschichten sind weniger fest und steif und sollen die Impaktenergie in Reibungs-, Wärme- und innere Energie umwandeln. Als Dämpfungsschichtmaterialien wurden ein Beton mit Altgummizuschlägen, zwei unterschiedliche Leichtbetone und zwei Infraleichtbetone geprüft. Unter den geprüften Deckschichtmaterialien befanden sich ein Carbonbeton und unterschiedliche Mischungen mit Kurzfaserbetonen, die teilweise auch mit hybriden 3D Bewehrungsstrukturen bewehrt wurden. Zunächst wurden die Materialen unter dynamischer Druck- und Zugbelastung im Split-Hopkinson-Bar geprüft. Diese kleinteiligen Versuche sollen dem Verständnis des dynamischen Materialverhaltens dienen und bilden gleichzeitig die Grundlage für eine mögliche spätere numerische Analyse der Verstärkungsschichtmaterialien, die gleichzeitig die Variation der Materialeigenschaften von Verstärkungsschichten erlaubt. Anschließend wurden die unterschiedlichen Dämpfungs- und Deckschichtmaterialien in einem größeren Probenmaßstab untersucht. Die Probekörper, die unverstärkt sowie unterschiedlich verstärkt untersucht wurden, waren vollflächig gelagerte Stahlbetonquader. Zunächst wurde das Dämpfungsschichtmaterial variiert, um die Dämpfungsschicht zu finden, die am meisten Energie umwandeln und somit die Schädigung der Stahlbetonquader am effizientesten reduzieren kann. Diese wurde danach unter unterschiedlichen Deckschichten kombiniert, um das geeignetste Deckschichtmaterial zu ermitteln.:Abstract i Kurzfassung iii List of Symbols xv List of Abbreviations xix 1 Objectives, Working Program, and Structure 1 1.1 Motivation 1 1.2 Overall Objectives 1 1.3 Working Program 1 2 State of the Art and Theoretical Background 3 2.1 Impact on Structural Elements 3 2.1.1 Soft and Hard Impact 3 2.1.2 Failure Modes Under Hard Impact Conditions 3 2.1.3 Large-Scale Impact Experiments 4 2.1.4 Impact Protection Layers 4 2.2 Introduction of Impact Protection Principles 4 2.2.1 Impact Protection in Nature 4 2.2.2 Technical Impact Protection Examples 9 2.2.3 Summary of Impact Protection Principles and Usable Materials 14 2.3 Mineral-Bonded Damping Layer Materials 15 2.3.1 Waste Tire Rubber Concrete 15 2.3.2 All-Lightweight Aggregate Concrete 16 2.3.3 Infra-Lightweight Concrete 17 2.4 Mineral-Bonded Cover Layer Materials 18 2.4.1 Strain-Hardening Cementitous Composites 18 2.4.2 Textile Reinforced Concrete 19 2.4.3 Hybrid-Fiber Reinforced Concrete 19 2.5 Bond Between Different Strengthening Layers 20 3 Materials under Investigation 21 3.1 Specimen Preparation 21 3.2 Damping Layer Materials 22 3.2.1 Waste Tire Rubber Concrete (WTRC) 22 3.2.2 All-Lightweight Aggregate Concrete With Liapor Aggregates (ALWAC-L) 23 3.2.3 All-Lightweight Aggregate Concrete With Ulopor Aggregates (ALWAC-U) 23 3.2.4 Porous Lightweight Concrete (PLC) 23 3.2.5 Infra-Lightweight Concrete (ILC) 23 3.2.6 Comparison of the Damping Layer Materials 24 3.3 Cover Layer Materials 27 3.3.1 Pagel TF10 CARBOrefit With Carbon Textile Reinforcement (P-C) 27 3.3.2 Strain-Hardening Limestone Calcined Clay Cement (SHLC3) 27 3.3.3 Comparison of the Cover Layer Materials 28 3.4 Partially Loaded Areas 30 4 Methodology of Split Hopkinson Bar Experiments 35 4.1 Experimental Setup and Methodology 35 4.1.1 Compressive Split Hopkinson Bar 35 4.1.2 Tensile Split Hopkinson Bar 36 4.1.3 Instrumentation 39 4.2 Evaluation Process 39 4.2.1 Impedance 40 4.2.2 Raw Data Analysis, Filtering, and Time-Shifting of Pulses 41 4.2.3 Stresses and Strains 42 4.2.4 Deformations 50 4.2.5 Forces and Impulses 51 4.2.6 Energy Absorption 52 4.2.7 Fracture Energy 53 4.2.8 Averaging of the Results 54 5 Compressive Split Hopkinson Bar Experiments 57 5.1 Failure Modes 57 5.2 Stresses and Strains 58 5.2.1 Dynamic Compressive Strength 58 5.2.2 DIF 59 5.3 Deformations 60 5.4 Forces and Impulses 61 5.4.1 Relative Transmitted Force 61 5.4.2 Impulse Transmission 63 5.4.3 Reduction of the Pulse Inclination 64 5.5 Energy Absorption 64 5.6 Conclusions 66 6 Tensile Split Hopkinson Bar Experiments 69 6.1 Failure Modes 69 6.2 Stresses and Strains 70 6.2.1 Dynamic Tensile Strength 70 6.2.2 DIF 71 6.3 Deformations 72 6.4 Forces and Impulses 73 6.4.1 Relative Transmitted Force 73 6.4.2 Impulse Transmission 74 6.4.3 Reduction of the Pulse Inclination 75 6.5 Energy Absorption 75 6.6 Fracture Energy 77 6.7 Conclusions 78 7 Methodology of Cuboid Experiments 79 7.1 Experimental Program 79 7.1.1 Specimen Dimensions and Experimental Setup 79 7.1.2 Experimental Scheme 81 7.2 Measurements Taken During the Experiments 83 7.2.1 Light Barriers 84 7.2.2 Resistor 84 7.2.3 Strain Gauges 84 7.2.4 Laser Doppler Vibrometer 85 7.2.5 Accelerometers 85 7.2.6 Load Cells 85 7.2.7 High-Speed Cameras and DIC 85 7.3 Measurements Taken Before and After the Experiments 86 7.3.1 Impactor Indentation 86 7.3.2 Burst Mass 86 7.3.3 Ultrasonic Pulse Velocity Measurements 86 7.3.4 Stimulation 87 7.4 Evaluation Process 88 7.4.1 Fracture and Damage Process 88 7.4.2 Impactor Velocity, Deceleration, Force, Stress, and Stress Rate 88 7.4.3 Impactor Indentation, Strain, and Strain Rate 90 7.4.4 Vertical Cuboid Deformation, Velocity, and Acceleration 92 7.4.5 Lateral Cuboid Deformation, Velocity, and Acceleration 93 7.4.6 Relative Cuboid Elongation in X- and Y-Direction 93 7.4.7 Strain Measurements on the Reinforcement Bars 94 7.4.8 Path and Derivative of the Support Forces 95 7.4.9 Burst Mass 96 7.4.10 Ultrasonic Pulse Velocity Measurements 96 7.4.11 Stimulation 97 7.4.12 Impulse and Momentum Conservation 99 7.4.13 Energy Conservation 100 7.4.14 Estimation of the Eigenfrequency of the Cuboids 101 8 Damping Layer Variation in Cuboid Experiments 103 8.1 Fracture and Damage Process 103 8.2 Impactor Velocity, Deceleration, and Force 105 8.3 Impactor Indentation 108 8.4 Vertical Cuboid Deformation, Velocity, and Acceleration 110 8.5 Lateral Cuboid Deformation, Velocity, and Acceleration 113 8.6 Relative Cuboid Elongation in X- and Y-Direction 115 8.7 Path and Derivative of the Support Forces 118 8.8 Ultrasonic Pulse Velocity Measurements 120 8.9 Stimulation With the Impulse Hammer 121 8.10 Stimulation With the Steel Impactor 124 8.11 Overview Over Forces, Stresses, Strains, and Their Rates 128 8.12 Impulse and Momentum Conservation 133 8.13 Energy Conservation 135 8.14 Dimensioning of the Required Damping Layer Thickness Depending on the Loading Velocity 136 8.15 Conclusions 137 9 Cover Layer Variation in Cuboid Experiments 139 9.1 Fracture and Damage Process 139 9.2 Impactor Velocity, Deceleration, and Force 141 9.3 Impactor Indentation 144 9.4 Vertical Cuboid Deformation, Velocity, and Acceleration 145 9.5 Lateral Cuboid Deformation, Velocity, and Acceleration 147 9.6 Relative Cuboid Elongation in X- and Y-Direction 149 9.7 Path and Derivative of the Support Forces 150 9.8 Ultrasonic Pulse Velocity Measurements 152 9.9 Stimulation With the Impulse Hammer 153 9.10 Stimulation With the Steel Impactor 155 9.11 Overview Over Forces, Stresses, Strains, and Their Rates 157 9.12 Impulse and Momentum Conservation 162 9.13 Energy Conservation 163 9.14 Conclusions 164 10 Conclusions of the Cuboid Experiments 167 10.1 Main Findings 167 10.2 Most Relevant Sensor Positions and Measurements 167 10.2.1 Digital Image Correlation (DIC) of the Impactor 167 10.2.2 Lateral Acceleration 167 10.2.3 Digital Image Correlation (DIC) of the RC Cuboid 168 10.2.4 Ultrasonic Pulse Velocity (UPV) Measurements 168 10.2.5 Stimulation With the Impulse Hammer and the Steel Impactor 168 10.3 Suggested Improvements to the Setup 168 10.3.1 High-Speed Cameras (HSC) 168 10.3.2 Acceleration Sensors 169 10.3.3 Support Forces 169 10.3.4 Strain Gauges 169 10.3.5 Temperature Sensors 169 10.4 Comparison of the Material Behavior in Compressive SHB and Cuboid Experiments 169 10.4.1 Scattering of Measured Values 169 10.4.2 Failure Modes 170 10.4.3 Loading and Strain Rates 170 10.4.4 Influences of Inertia 170 10.4.5 Forces and Stresses 171 10.4.6 Energy Absorption 171 11 Summary and Conclusions 173 11.1 Compressive SHB Experiments 173 11.2 Tensile SHB Experiments 173 11.3 Damping Layer Variation in Cuboid Experiments 174 11.4 Cover Layer Variation in Cuboid Experiments 174 11.5 Conclusions 175 12 Outlook 177 12.1 Split Hopkinson Bar Testing 177 12.2 Strengthening Procedure 177 12.3 Large-Scale Impact Testing 177 12.4 Design 178 Bibliography 179 List of Figures 193 List of Tables 199

The goal of this work was to quantify the mechanical properties of cellulose nanocrystal (CNC)-based thin films using a polystyrene (PS) structuring approach. This structuring approach was used to biaxially wrinkle CNC-polymer and all-CNC films, in order to assess how changes in the film fabrication process affected the elastic modulus of these films. All films were prepared on pre-stressed PS substrates and structured by heating them above the glass transition temperature of PS, which caused the substrates to shrink and the films to wrinkle biaxially. CNC-polymer films were prepared using the layer-by-layer approach, where three parameters were modified to obtain films of varying compositions: 1) type of polymer (xyloglucan, XG, or polyethyleneimine, PEI), 2) polymer concentration (0.1 wt% or 1 wt%), and 3) film thickness (i.e., number of deposited bilayers). After these films were structured, their elastic moduli were calculated to be 70 ± 2 GPa for CNC-XG0.1, 72 ± 2 GPa for CNC-PEI0.1, and 32.2 ± 0.8 GPa for CNC-PEI1.0 films, indicating that the mechanical properties of CNC-polymer films changed with film composition. This structuring method was also found to provide a humidity-independent measurement of the modulus due to the irreversible nature of the wrinkling. Next, to prepare all-CNC films, CNC suspensions were evaporated under conditions designed to control the film thickness (using 0.005 wt% – 8 wt% CNC suspensions) and CNC nanoparticle orientation (chiral nematic, isotropic, or uniaxial). Suspensions were dried slowly under vacuum, quickly by heating, or by spin-coating to form films with chiral nematic, isotropic, or uniaxial (radial) CNC orientations, respectively. Following structuring, these wrinkled films showed unique morphologies that changed with nanoparticle orientation, suggesting that their mechanical properties are dependent on the CNC orientation within the films. The work presented in this thesis implies that the mechanical properties of films fabricated from hygroscopic bio-based nanomaterials can be assessed in a humidity-independent way by using the structuring method presented. Quantifying the mechanical properties of these films is critical to assess the potential applications of CNCs, where CNC-based materials may be used in developing paper-based electronics, extracellular matrix mimics, and plant cell wall mimics. / Thesis / Master of Science (MSc)