Diverse conformational transitions and aggregations of regioregular head-to-tail polyhexylthiophene in different environments have been studied by means of AFM and UV-vis spectroscopy. A helical conformation of the main chain with 12 thiophenes rings per each helical turn has been proposed. Length of the particles varies from several nanometers to several hundreds nanometers and can be adjusted by the solvents composition or concentration of PATs. Such well-defined organic semiconductor 1D particles can be used as building blocks for future nanoscale and molecular level electronic devices. Oligothiophenes represent one of the most promising class of semiconductive materials for FET fabrication because of their good mobility and environmental stability. However, most of unsubstituted oligothiophenes are insoluble that suppresses their potential industrial utility. On the first stage of the work, conformation, crystalline structure, molecular packing and charge carrier mobility of the highly soluble regiochemically pure [Beta]-substituted sexithiophene were systematically studied. It was found that [Beta, Beta´]-DH6T possesses moderate PR-TRMC charge carrier mobility, but rather low field-effect mobility. The investigation showed that such a poor macroscopic electrical properties of [Beta, Beta´]-DH6T originate neither from the twist of the conjugated system nor from the crystalline disorder, but rather from low-dense crystalline packing and "wrong" molecular orientation. To overcome these obstacles two thiophene-based azomethines were designed to optimize a solubility, self-assembly, and a charge carrier mobility. The idea was to utilize the ability of the amide group to form strong hydrogen bonds in non-polar solvents and in solid state, but to be easily broken in presence of polar solvents. Thus, at the stage of a dissolution and a deposition, when the solubility is important, the hydrogen bonding can be "switched off" simply by addition of polar solvents and then, after the removal of polar additives, the self-assembly can be "switched on". It was found that incorporation of azomethine and amide moieties in the [Alpha, Omega]-position, and hexyl chains in [Beta]-position of quaterthiophene, indeed considerably improves the self-assembly properties without suppression of the solubility. Self-assembly of azomethine oligomers with (QT-amide) and without amide moieties (QT-aniline) were monitored by UV-vis, XRD, and AFM. It was found that QT-amide, processed from solution, forms highly ordered layered (terrace) structures. This aggregation mode is similar to the self-assembly of unsubstituted conjugated oligomers (such as pentacene) occurred upon their evaporation in vacuum. The sum of charge carrier mobilities (PR-TRMC data) for QT-aniline was shown to be below the detectable limit, but the mobility of QT-amide was determined to be 1.10-2 cm2 V-1 s-1. The later is comparable with the mobilities of the best organic semiconductors. All these significant differences in properties of related compounds can be attributed to the hydrogen bonding between QT-amide molecules responsible for the observed self-assembly.

La presente tesis aborda el estudio de materiales derivados de hidrocarburos aromáticos policíclicos (HAP) intercalados con metales alcalinos. El piceno ([5]fenaceno) ha sido descrito recientemente como un nuevo material superconductor al ser intercalado con tres equivalentes de potasio. Por ello, se describe una nueva metodología fotoquímica desarrollada para la obtención de [n]fenacenos, entre los que se encuentra el piceno. Se describe la obtención, la caracterización y la medición de las propiedades de hidrocarburos aromáticos intercalados en fase sólida con metales alcalinos, principalmente con potasio. También se incluye el estudio de especies aniónicas, derivadas de hidrocarburos aromáticos en disolución, concretamente del sistema Li-bifenilo en DME.

In this diploma thesis, the interactions between polyelectrolyte and surfactant at low and also at high concentration were studied. There was used pyrene as fluorescent probe during the fluorescence spectroscopy measurement, a cationic surfactant cetyltrimethylammonium bromide and as a main polyelectolyte has been chosen sodium polystyrene sulfonate at 1 MDa molecular size. In the medium containing 0.15 M NaCl we could observed a creation of the complexes – precipitates in the surrounding of CMC concentration and behind of this concentration. In the mixtures containing sodium polystyrene sulfonate and hyaluronan together, there was stronger tend to keep aggregation properties of sodium polystyrene sulfonate during difference concentration ratios. Beyond CMC concentration, hyaluronan starts to influence the aggregation properties of the system as well.

Recently, conductive polymer/carbon nanomaterials have drawn attention for use in corrosion inhibition, sensors, energy storage devices, and coatings for electromagnetic shielding applications due to their good mechanical properties and electronic conductivity. Therefore, efforts have been made to find fast and facile methods for the synthesis and development of these hybrids that allow control over key parameters, such as the thickness of the conductive polymer coating. In this study, such hybrids were prepared using polyaniline (PANI) as the conductive polymer and vapor-grown carbon nanofibers (VGCNFs) as the carbon nanomaterial or filler by a semi-dilute in situ polymerization method to be evaluated for their effectiveness as corrosion inhibitory additives to alkyd paints. Spectroscopic, colorimetric, and electric properties of PANI-coated VGCNFs were investigated. The thickness of the PANI coating, along with other parameters, impacts the behavior and mechanisms by which the nanomaterial performs its role in a given application, particularly in the corrosion inhibition processes. Thus, different synthesis conditions, including pretreatment of the nanofibers, the presence of sodium dodecyl sulfate (SDS) surfactant, PreT-VGCNF/ANI ratios (w/w), and polymerization times were tested and their effects on the PANI thickness were microscopically and statistically evaluated. It was found that only different PreT-VGCNF/ANI ratios allowed definite control of the PANI thickness. No clear effect on the thickness was observed after three hours of polymerization. The presence of SDS and pretreatment of VGCNFs displayed a synergistic effect on the appearance and thickness of the PANI film. PANI-coated VGCNF additives, with PANI in the leucoemeraldine base (LEB) and emeraldine base (EB) forms, were synthesized using a PreT-VGCNF/ANI ratio of 0.4 in the presence of SDS. Cold-rolled steel coupons were coated with 20-30 ìm thick alkyd paint coatings, and their electrochemical behavior was investigated by open circuit potential (OCP) and electrochemical impedance (EIS) measurements. The results indicate that, overall, EB/VGCNF additive performed better as a corrosion inhibitor, followed by PreT-VGCNF and LEB/VGCNF additives.

Quinoa is coated with a thin layer of saponins, glycosylated triterpenoids, that produce a bitter flavor when consumed. The average saponin content in commercial varietals from Bolivia average around 2.7% saponins and organoleptic testing shows the threshold for noticing a bitter flavor is below 0.12% (Medina-Meza et al., 2016). Current industrial processing methods use a combination of abrasion and turbulent water flow to remove saponin. This study will address the following research question: How will grain-to-grain and grain-to-surface abrasion affect the processing time to remove saponin from quinoa? In particular, can effective saponin removal be achieved in less than 10 minutes without washing with water? Three different laboratory scale systems for generating grain-to-grain abrasion alone and in combination with grain-to-surface abrasion were constructed. Preliminary studies using mass balance and visual observation found the tubular system removed 4.45% of the quinoa mass in saponin containing fractions compared to the conical system (1.33%) and fluidized bed (0.62%). After preliminary studies, a saponin estimation method was adapted and the conditions of the tubular system were determined. A randomized experiment was carried out in triplicate at three levels of time (5, 10, and 15 minutes) and mass (200, 300, and 400 grams). The effect of surface roughness in the tubular system was also evaluated. The samples were collected and saponin content in each sample was quantified using the adapted method. The saponin levels were compared to commercially processed quinoa in the market. The processing conditions of 15 minutes at an input mass of 300 grams yielded the lowest saponin level of 0.19%. The four processing conditions of (10 minutes/200 grams, 10 minutes/400 grams, 15 minutes/200 grams and 15 minutes/300 grams) were statistically different (p The tubular system showed promise for reducing process time and saponin content in commercially processed quinoa without washing. However, further experimentation is needed for industrial implementation. The system would provide the industry with a sustainable process with better saponin removal capacity.

Cerium oxide (ceria)-based materials in the nanoscale regime are of significant fundamental and technological interest. Nanoceria in pure and doped forms has current and potential use in solid oxide fuel cells, catalysis, UV- screening, chemical mechanical planarization, oxygen sensors, and bio-medical applications. The characteristic feature of Ce to switch between the +3 and + 4 oxidation states renders oxygen buffering capability to ceria. The ease of this transformation was expected to be enhanced in the nanoceria. In most the practical scenarios, it is necessary to have a stable suspension of ceria nanoparticles (CNPs) over longer periods of time. However, the existing literature is confined to short term studies pertaining to synthesis and property evaluation. Having understood the need for a comprehensive understanding of the CNP suspensions, this dissertation is primarily aimed at understanding the behavior of CNPs in various chemical and physical environments. We have synthesized CNPs in the absence of any surfactants at room temperature and studied the aging characteristics. After gaining some understanding about the behavior of this functional oxide, the synthesis environment and aging temperature were varied, and their affects were carefully analyzed using various materials analysis techniques such as high resolution transmission electron microscopy (HRTEM), UV-Visible spectroscopy (UV-Vis), and X-ray photoelectron spectroscopy (XPS). When the CNPs were aged at room temperature in as-synthesized condition, they were observed to spontaneously assemble and evolve as fractal superoctahedral structures. The reasons for this unique polycrystalline morphology were attributed to the symmetry driven assembly of the individual truncated octahedral and octahedral seed of the ceria. HRTEM and Fast Fourier Transform (FFT) analyses were used to explain the agglomeration behavior and evolution of the octahedral morphology. Some of the observations were supported by molecular dynamic simulations. Poly (ethylene glycol) (PEG) and ethylene glycol (EG) were used to control the kinetics of this morphology evolution. The ability to control the agglomeration of CNPs in these media stems from the lower dielectric constant and an increased viscosity of the EG and PEG based solvents. CNPs when synthesized and aged in frozen conditions, i.e. in ice, were found to form one dimensional, high aspect ratio structures. A careful analysis has provided some evidence that the CNPs use the porous channels in ice as a template and undergo oriented attachment to form nanorods. When the aging treatment was done near freezing temperature in solution, the nanorods were not observed, confirming the role of channels in ice. When synthesized in aqueous media such as DI water, PEG and EG; CNPs were observed to exhibit a reversible oxidation state switching between +3 and +4. Band gap values were computed from the optical absorption data. The changes in the band gap values observed were attributed to the changes in the oxidation state of CNPs as opposed to the quantum confinement effects, as expected in other nanoparticle systems. The work presented in this dissertation demonstrates, with evidence, that in order to obtain a comprehensive understanding of the properties of nanoscale materials it is of paramount importance to monitor their behavior over relatively longer periods of time under various ambient environments. While the solution based techniques offer a versatility and low cost route to study the fundamental properties of nanomaterials, they suffer some inherent problems such as precursor contamination and uncontrolled chemical reactions. Especially when analyzing the behavior of ceria-based materials for applications like solid oxide fuel cells, a great control in the density and crystalline quality are desired. In order to achieve this, as a first step pure ceria thin films were synthesized using oxygen plasma assisted molecular beam epitaxy (OPA-MBE). The ceria films were analyzed using various in situ and ex situ techniques to study the crystal structure, growth mode and epitaxial quality of the films. It was observed that the epitaxial orientation of the ceria films could be tuned by varying the deposition rate. When the films were grown at low deposition rate (< 8 Å/min) ceria films with epitaxial (200) orientation were observed where as the films grown at high deposition rates (up to 30 Å/min) showed (111) orientation. Theoretical simulations were used to confirm some of the experimental facts observed in both nanoparticles and thin films.

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