Facile Synthesis of Novel Prussian Blue-Lipid Nanocomplexes

Prussian blue (PB) is known for its multiple applications ranging from fine arts to therapeutics. More recently, PB nanoparticles have been pointed to as appealing photothermal agents (PA) when irradiated with wavelengths corresponding to the biological windows, namely regions located in the near infrared (NIR) zone. In addition, the combination of PB with other components such as phospholipids boosts their therapeutical potential by facilitating, for instance, the incorporation of drugs becoming suitable drug delivery systems. The novelty of the research relies on the synthesis procedure and characterization of hybrid lipid-PB nanoparticles with a high yield in a friendly environment suitable for photothermal therapy. This goal was achieved by first obtaining insoluble PB coated with oleylamine (OA) to facilitate its combination with lipids. The resulting lipid-PB complex showed a monomodal distribution of sizes with an overall size of around 100 nm and a polydispersity index of about 0.200. It highlights one critical step in the synthesis procedure that is the shaking time of the mixture of PB-OA nanoparticles with the lipid, which was found to be 48 h. This time assured homogeneous preparation without the need of further separation stages. Samples were stable for more than three months under several storage conditions. View Full-Text Keywords: Prussian blue nanoparticles; lipid nanoparticles; photothermal agent; photothermal therapy; NI

Nanostructured Polythiophene Materials for Electrochromic Applications

The development of semiconductor polythiophenes for optoelectronic applications requires tailored design and synthetic strategies to obtain materials with tunable optical and electronic properties and morphology in order to enhance their properties. To achieve this goal, the de-sign, synthesis, and characterization of new nanostructured polythiophene materials was studied and tested in terms of processability, performance and stability through the assembly of solid-state electrochromic devices (ECDs). The use of films with poly(3-hexylthiophene-2,5-diyl) nanoparticles (P3HT-NPs) is reported, prepared by the nanoprecipitation method using water-based solutions with enhanced electrochromic properties. Additionally, it is reported the synthesis of a new class of thiophene-based electrochromic polymers using a repeated unit of the same linear thienyl-phenyl-thienyl-thienyl backbone. The tuning of the optoelectronic properties was achieved by introducing alkyl or alkoxy substituents in the thiophene unit and/or the presence of either -CH=CH- or -CH2-CH2- linkers, connecting the repeated units and acting as conjugation modulators. The design of the newly synthesized polymers was op-timized to obtain a yellow-colored polymer with low redox potentials and demonstrate that the use of nanoparticle films deposited from water solutions, significantly improves their elec-trochromic performance. In a different approach, stable dispersions of carbon nanotubes (CNTs) were devel-oped, through the establishment of π-π stacking interactions between the CNTs and a newly synthesized pyrene-appended polythiophene. Hybrid thin-film composites were produced, and their electrochromic performance was evaluated through the assembly of solid-state ECDs. Lastly, the use of copper-nanowire/reduced-graphene-oxide (CuNWs-rGO) hybrid coatings was explored as transparent and conductive material for flexible electronic applica-tions, through their use as electrodes in indium-tin-oxide (ITO)-free electrochromic displays.O desenvolvimento de politiofenos semicondutores para aplicações optoelectrónicas reque-rem um planeamento e estratégias sintéticas elaboradas de maneira a obter materiais com pro-priedades e morfologias ajustáveis para melhorar as suas propriedades. Para atingir este obje-tivo, foram feitos o planeamento, síntese e caracterização de novos materiais nano-estrutura-dos de politiofenos que foram testados no que diz respeito a processabilidade, desempenho e estabilidade através da montagem de dispositivos electrocrómicos no estado sólido (ECDs). O uso de filmes com nanopartículas de poli(3-hexiltiofeno-2,5-diilo) (P3HT-NPs) é reportado, preparados pelo método de nano-precipitação usando soluções à base de água com proprie-dades electrocrómicas melhoradas. Adicionalmente, é também reportada a síntese de uma nova classe de polímeros baseados em tiofeno utilizando a mesma estrutura base linear de tienil-fenil-tienil-tienil. A modelação das propriedades optoelectrónicas foi alcançada através da introdução de substituintes alquil ou alquiloxi na unidade de tiofeno e/ou a presença de espaçadores -CH=CH- ou -CH2-CH2-, conectando as unidades repetidas e atuando como mo-duladores de conjugação. O planeamento da síntese de novos politiofenos foi otimizado de maneira a obter um polímero de coloração amarela com um baixo potencial redox e demons-trar que, o uso de filmes com nanopartículas depositados através de soluções baseadas em água melhora significativamente o seu desempenho electrocrómico. Numa abordagem diferente, dispersões estáveis de nanotubos de carbono (CNTs) fo-ram desenvolvidas, baseadas em interações π-π entre nanotubos de carbono e um novo poli-tiofeno sintetizado com uma unidade de pireno incorporada. Filmes finos de compósitos hí-bridos foram produzidos, e o seu desempenho electrocrómico foi avaliado através da monta-gem de dispositivos electrocrómicos no estado sólido. Por último, o uso de uma camada hí-brida de nanofios de cobre/óxido de grafeno reduzido (CuNWs-rGO) foi explorada como ma-terial transparente e condutor para aplicações eletrónicas flexíveis, através do seu uso como elétrodos em dispositivos electrocrómicos sem óxido de estanho e índio (ITO)

Printed electronics for ubiquitous computing applications

Dissertação para obtenção do Grau de Doutor em QuímicaThis Ph.D. project is focused on the synthesis of functional inorganic materials, their formulation into inks and their deposition using inkjet printing on non-conventional substrates, such as paper, with the ultimate goal of advancing the state-of-the-art in the area of printed electrochromic displays. Other materials, inks,techniques and substrates were also explored. The first step in building a printed electrochromic display is to synthesize the functional materials necessary for the different layers of the device; this part of the work focused on inorganic electrochromic materials (tungsten oxide and vanadium oxide) and on transparent conductive oxides (TCO). ATO(antimony tin oxide) was synthesized using the Pechini method and the results obtained were promising. Tungsten oxide and vanadium oxide nanoparticles were also synthesized via a sol-gel route. FTIR,Raman and X-ray diffraction spectroscopic measurements showed that tungsten oxide nanoparticles synthesized via sol-gel are mainly in an amorphous state, with hexagonal crystalline domains, and allowed the analysis of the hydration extent of those nanoparticles. Vanadium oxide gel synthesized in this work is similar to those previously described in the literature, consisting of V2O5.6H2O, with microstructures similar to orthorhombic V2O5, while Raman spectroscopy also showed the presence of amorphous domains. The nanoparticle sizes were measured combining Dynamic Light Scattering, sedimentation and microscopic techniques (AFM and TEM). Tungsten oxide particles presented an average nanoparticle size between 160 and 200 nm, and vanadium oxide of 60 nm. The nanoparticles were used to produce ink formulations for application in inkjet printing. In addition to tungsten oxide and vanadium oxide, other electrochromic materials were printed. This part of the work examined the possibility of inkjet printing several organic (poly(thiophene)s) and inorganic electrochromic materials (metal oxides and metal hexacyanometallates) and also evaluated the performance of the resulting electrochromic devices. Poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate), poly(3-hexylthiophene), tungsten oxide, vanadium oxide and Prussian blue were inkjet printed on flexible substrates, such as plastic and paper. Solid-state electrochromic devices were assembled at room temperature on plastic and on paper substrates, without sintering the printed films, showing, in some cases, excellent contrast between the on and off state. The tungsten oxide and vanadium oxide devices were then tested through spectroelectrochemistry by Visible/NIR absorption spectroscopy. Tungsten oxide showed a dual spectroscopic response depending on the applied voltage and vanadium oxide presented several redox steps, which give rise to a variety of color transitions, also as a function of the applied voltage. Color space analysis was used to characterize the electrochromic transitions; monitorization of the color contrast and cycling tests, as well as techniques such as cyclic voltammetry, were also used to characterize device performance

Chemical approaches to ubiquitous computing

Dissertação apresentada para obtenção do Grau de Doutor em Química, perfil de Química Física, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologi

Facile Synthesis and Versatilities of Polyanthraquinoylamine Nanofibril Bundles with Self Stability and High Carbon Yield

A facile synthesis for nanosized conducting polymers with inherent self-stability and multi-functionalities is a main challenge. Here we simply synthesize intrinsically self-stabilized nanofibril bundles of poly(1-anthraquinoylamine) (PAQ) by a template-free method. The critical polymerization parameters were studied to significantly optimize the synthesis, size, properties, and functionalities of the resulted fine nanofibrils with a diameter of ca. 30 nm and length of ~6 μm. The PAQ obtained with ammonium persulfate possesses higher polymerization yield, purer composition, higher conductivity, better melting behaviour, higher thermostability, lower burning enthalpy, and slower degradation than that with other oxidants. Furthermore, the polymer nanofibrils exhibit high self-stability, powerful redispersibility, high purity, and clean surface because of a complete avoidance of the contamination from external stabilizer. The PAQ exhibits widely controllable conductivity moving across ten orders of magnitudes from 10^-9^ to 50 S/cm, photoluminescence, lead-ion adsorbability, very high thermostability in air and extremely high char yield in nitrogen at 1000˚C. These materials would be useful as advanced materials including photoluminescent materials, highly cost-effective carbon precursors, sorbents of toxic metal ions, and cost-efficient conductive nanocomposite with low percolation threshold

Functionalized Silica Gel for Adsorption of Cesium from Solution

Mesoporous silica gel containing embedded phosphotungstic acid (PTA) was synthesized by sol-gel co-condensation of tetraethyl orthosilicate with PTA in acidic media. The obtained material had high Brunauer-Emmett-Teller Theory (BET) surface area and pore volume. A characteristic band of the Keggin structure of PTA was present in its FT-IR spectrum while its X-ray diffraction patterns were absent. This proved the embedding of PTA on a sub-molecular level and not as a second phase. Acidic sites were determined by neutralization with base in aprotic solvent, followed by titration of the remaining base with an acid. The material demonstrated high adsorption capacity of Cs. Kinetic studies showed that the adsorption data correlates strongly with the pseudo-second order model. At higher temperatures, the nature of adsorption fit the Langmuir model extremely well. The obtained results can be used in the development of an effective adsorbent for clean-up of water contaminated by radioactive 137Cs

Plasmonic Doped Semiconductor Nanocrystals: Properties, Fabrication, Applications and Perspectives

Degenerately doped semiconductor nanocrystals (NCs) are of recent interest to the NC community due to their tunable localized surface plasmon resonances (LSPRs) in the near infrared (NIR). The high level of doping in such materials with carrier densities in the range of 1021 cm^-3 leads to degeneracy of the doping levels and intense plasmonic absorption in the NIR. The lower carrier density in degenerately doped semiconductor NCs compared to noble metals enables LSPR tuning over a wide spectral range, since even a minor change of the carrier density strongly affects the spectral position of the LSPR. We focus on copper chalcogenide NCs and impurity doped metal oxide NCs as the most investigated alternatives to noble metals. We shed light on the structural changes upon LSPR tuning in vacancy doped copper chalcogenide NCs and deliver a picture for the fundamentally different mechanism of LSPR modification of impurity doped metal oxide NCs. We review on the peculiar optical properties of plasmonic degenerately doped NCs by highlighting the variety of different optical measurements and optical modeling approaches. These findings are merged in an exhaustive section on new and exciting applications based on the special characteristics that plasmonic semiconductor NCs bring along.Comment: 97 pages, 33 figure

廃水処理と資源回収のための機能性吸着材料の開発

この博士論文は一時全文を公表していましたが、公表に適さないやむを得ない事由ができ要約のみの公開としました（2020年4月3日）筑波大学 (University of Tsukuba)201