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<p>  </p> <p>The additive manufacturing of energetic materials is a novel way to alter the properties of an energetic material without necessarily changing its chemical structure. There are many methods of additive manufacturing which can be applied to energetic material fabrication, each of which have unique advantages and disadvantages. The most well characterized additive manufacturing method is the commercially refined technique of fused filament fabrication (FFF) printing. FFF manufacturing techniques can be applied to additively manufacture thermoplastic energetic materials. The thermoplastic aluminum and polyvinylidene difluoride (Al/PVDF) system is suitable for manufacture with FFF techniques, shapeable into pyrotechnics with custom geometries using commonly available FFF printers. This theoretically allows Al/PVDF systems to be tailored for a wide variety of multifunctional needs, such as reactive structures. Following a literature review describing energetic material additive manufacturing techniques, this thesis focuses on the creation of outwardly identical Al/PVDF samples and the use of a geometric correction factor to control for uneven feedstock diameter. By varying the infill pattern, infill density, and interior geometry, different sample energy densities were obtained and observed during combustion. High speed videography measurements and the mass of individual samples were used to estimate the overall energy release rate. An Ashby plot contrasting the energy density and energy release rate was obtained. While full density printed samples burned similar to cast propellant strands in a linear burn, the energy release rates of additively manufactured Al/PVDF could be increased via convective combustion by varying the infill type and density. These results have significance for the fields of structural energetic materials and for additive manufacturing studies of energetic materials.</p>

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<p>Some molecular complexes exhibiting bistability between two different spin states have been subject to vast investigations. Spin crossover and valence tautomerism interconversion molecular compounds are such examples showing this dynamic switching behavior and are a route toward designing molecular devices with a facile readout due to the change in the spin state that accompanies the change in conductance. Due to their extensive potential applications in industry and research, they are among the most interesting topics in spintronics. Spin state switching processes provide the foundation for applications in molecule-based devices. The main goal is to study the parameters that affect the intramolecular electron transfer between different spin states in spin crossover molecular thin films and the electron transfer between the metal center and redox-active ligands in valence tautomer thin films. </p> <p>Because substrate effects are important for any molecular-based device, there are increasing efforts to study the influence of the substrate on spin state transition. While some non-metallic substrates like graphite seem to be promising from experimental measurements, theoretical and experimental studies indicate that 2D semiconductor surfaces will have minimum interaction with spin crossover molecules.</p> <p>In this work, the functionality of two different spin crossover molecules sublimated on the ferroelectric Polyvinylidene Fluoride Hexafluoropropylene (PVDF-HFP) layer and 2D Ti3C2 MXene thin film is studied. We report the temperature-dependent spin state transition of spin crossover molecules, [Fe{H2B(pz)2}2 (bipy)], thin films, and valance tautomer [Co(sq)(cat)(3-tpp)2] thin films. Using a UV-Vis spectrometer and a specific lab-built sample holder we were able to perform the measurement at temperatures as low as 90 K and as high as 440 K. Temperature-dependent UV-Vis data show that the transition temperature from the high spin state to the low spin state and vice versa is well below the room temperature. However, for isothermal switching purposes, we designed and fabricated a bilayer device with PVDF-HFP thin films as the substrate to facilitate isothermal switching close to room temperature. The retention of voltage-controlled nonvolatile changes to the electronic structure in bilayers of PVDF-HFP/[Fe{H2B(pz)2}2(bipy)] and PVDF-HFP/[Co(sq)(cat)(3-tpp)2] strongly depends on the thickness of the PVDF-HFP layer. </p> <p>While the electric transport measurement revealed that doping the SCO layer with Ti3C2 MXene flakes can significantly improve the conductivity of the spin crossover molecular thin films, the temperature-dependent UV-Vis measurements represent that the adjacent MXene layer can cause a lock in the given spin state or a change in the transition temperature dramatically.</p> <p><br></p>

In nature, microscopic surface textures impact useful function, such as the drag reduction of shark skin (Dean & Bhushan, 2010) and superhydrophobicity of the lotus leaf(Pan, Kota, Mabry, & Tuteja, 2013). In this study, we explore these phenomena by re-creating microscopic surface textures via the method of interfacial flow instability in drying polyvinylidene fluoride (PVDF) acetone solutions. In general, PVDF films can be made using either spin coating or electrospray deposition with various weight concentrations in acetone. In order to study the morphology of the porous structure of PVDF films, wet deposition samples were fabricated by spin coating or near-field electrospray. Possible theories are discussed and examined to explain the formation of these porous structures resulting in development of a well-controlled method to create porous PVDF films with various pore sizes and pore densities. All samples are characterized and found to exhibit superhydrophobicity and drag reduction. To connect porous PVDF film morphology to the established field of dry particle fabrication, PVDF particle synthesis by far-field electrospray is also reviewed and discussed. An established method to generate polymer particles of different morphologies in other polymers (Almeria-Diez, 2012) by electrospray drying is confirmed using PVDF as well. Due to the ability of scalable and re-configurable electrospray, the microscopic surface textures can be applied to areas of any size to reduce drag or impart water-repelling properties.

Изучено влияние природы растворителя и магнитного порошка на процесс кристаллизации поливинилиденфторида (ПВДФ). Методам изотермической микрокалориметрии определены энтальпии разбавления ПВДФ в растворителях различной химической природы. Полученные данные использованы для расчета параметров Флори-Хаггинса. Получены полимерные композиционные материалы на основе ПВДФ и порошков никеля и железа. Получены зависимости степени кристалличности композиций и максимумов температур плавления от состава. Изучен их фазовый состав методами инфракрасной спектроскопии и дифференциальной сканирующей калориметрии. / The influence of the nature of the solvent and magnetic powder on the crystallization process of polyvinylidenefluoride (PVDF) has been studied. The enthalpies of dilution of PVDF in solvents of various chemical nature are determined by the methods of isothermal microcalorimetry. Data used to calculate Flory-Huggins parameters. Polymer composite materials based on PVDF and powders of nickel and iron are obtained. The dependences of the degree of crystallinity of the compositions and maxima of the melting points on the composition were obtained. The phase composition was studied using infrared spectroscopy and differential scanning calorimetry.

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Abstract Template assisted deposition was used to produce various nanomaterials including simple nanowires, nanorods, multi-segmented metal nanowires, core-shell nanowires, alloy and polymer wires and tubes. Anodized aluminum oxide (AAO) membranes were used as templates for the growth of the various structures using an electrochemical deposition method and also by wetting the porous templates. In the electrochemical deposition method, the pore size of the templates affects the rate of synthesis and the structures of the nanomaterials while in the wetting method, the viscosity and reaction time in the polymer solution influence the structures of the nanomaterials. A conventional two-step anodization procedure was used to synthesize thick AAO templates with porous hexagonal channels at a constant applied voltage and temperature. A maximum thickness of over 180 µm oxide layer could be fabricated using mild anodization at 60 V and 80 V. Compared to conventional mild anodization, these conditions facilitated faster growth of oxide layers with regular pore arrangement. Polyethylene glycol (PEG) containing ferromagnetic nanowires were synthesized using template assisted electrochemical deposition method. During the synthesis, simultaneous deposition of polymer and metal ions resulted nanowires coated with a uniform layer of PEG without interfering with the structure and magnetic properties of the nanowires. PEG-coated Ni nanowires were embedded in polyethylene diacrylate (PEGDA) matrix after the removal of the AAO templates. Comparison of results with and without a magnetic field during embedding showed that the presence of magnetic field supported embedding of nanowire arrays in polymer. Influence of using AAO templates with several pore diameters for the synthesis of bimetallic nanowires were studied by growing Ni-Fe and Ni-Co bi-metallic nanowires. At a constant applied current by using templates with a pore diameters of 60 nm alloy formed while with a pore diameter of 130 nm core-shell nanowires formed. Polyvinylidene fluoride (PVDF) films and nanotubes were synthesized using a solution recrystallization method that favored the formation of piezoelectric β phase thin films. Variation in the concentration of polymer in the mixture solution allowed synthesis of different types of structures such as PVDF composites, nanorods and nanocrystals with tunable morphologies. Keywords: One-dimensional structures, electrodeposition, porous alumina, ferromagnetic nanostructures, magnetic core-shell nanowires, alloys, polymer composite, stimuli-active, PEGDA, azobenzene, and PVDF.

På grund av det rådande miljöhotet så bör fokus för forskning och utveckling i ämnet riktas åt att utnyttja så många förnybara energikällor som möjligt, samt även optimera dessa för största möjliga energiupptagning. Vind, vatten och solljus är välkända och väl utformade källor för energi. Huruvida vatten i form av regn kan utnyttjas och dess potential kommer studeras i det här arbetet. Materialval och konstruktionslösningar står i centrum för arbetet. Vidare så studeras dess bakgrunder för utvinningsmetoderna och dess grundläggande principer tas upp för att skapa en bättre förståelse för möjligheterna att utnyttja tekniken. Fortsättningsvis så har rådande potentiella användningsområden och kommande utmaningar diskuterats utförligt. / Because of the prevailing environmental threat, focus for research and development in the subject should aim towards taking advantage of as many renewable energy sources as possible aswell as optimizing them to convert as much energy as possible. All renewable energy must be utilized, but above all, also optimized. Wind, water and sunlight are well-known and well-designed sources of energy. Whether water in the form of rain can be utilized and its potential as a sustainable commercial method will be studied in this paper. Material selection and design solutions are at the heart of the work. Furthermore, its backgrounds for the extraction methods are studied and its basic principles are addressed to create a better understanding of the possibilities of utilizing the technology. Moreover, the current potential uses and future challenges have been discussed in detail.