Highly fluorescent conjugated polymers (CPs) are an important class of biomaterials used for various biological applications including labelling, sensing, and delivery of biological substances. Synthetic versatility and tunable emission make CPs a superior class of biomaterials. Understanding the structure-function relationship of CPs plays a vital role in designing high performing biomaterials. The cationic CPs are self-assembled to conjugated polymer nanoparticles (CPNs) in an aqueous environment due to their amphiphilicity. The physical and biophysical properties of CPNs are highly dependent on the chemical functionality and backbone structure of CPs. Modulation of the surface property and backbone structure of CPNs play an important role for efficient internalization of CPNs into cells. The goal of this dissertation is to understand the structure function relationship of CPNs in an aqueous environment and the change in their photo physical properties upon the self-assembly of CPNs with different backbone structure upon complexation with biologically significant polysaccharides and cell membrane. This work presents the self-assembly of a set of four cationic CPs with different connectivity and backbone structure upon complexation with a linear polyanion hyaluronic acid (HA). The study of photo physical properties changes upon the complexation with series of Glycosaminoglycans (GAGs) provides more insight about how the self-assembly behavior of cationic CPs changes upon the exposure to negatively charged polysaccharides. The understanding of the self-assembly of CPNs with negatively charged biologically important macromolecules under in vitro conditions can give us an idea of photophysical property changes of CPNs during the treatment of CPNs in the cellular environment. The study of the interaction of CPNs with cell membranes using scanning ion conductance microscopy (SICM)-based topography, potential mapping, and confocal microscopy imaging is presented. CPNs are able to induce transient pore like feature formation on the cell membrane during the cellular internalization process. A comparative study of cellular labelling and delivery of siRNA of five CPNs with guanidine motif is presented. The subcellular localization and delivery of siRNA were dependent on the side chain hydrophilicity. The CPNs fabricated with hydrophilic aminoethoxyethanol possesses excellent cellular imaging with higher siRNA delivery.

The extracellular matrix is (ECM) is a network of large, structural proteins and polysaccharides, important for cellular behavior, tissue development and maintenance. Present thesis describes work exploring ECM as scaffolds for tissue engineering by manipulating cells cultured in vitro or by influencing ECM expression in vivo. By culturing cells on polymer meshes under dynamic culture conditions, deposition of a complex ECM could be achieved, but with low yields. Since the major part of synthesized ECM diffused into the medium the rate limiting step of deposition was investigated. This quantitative analysis showed that the real rate limiting factor is the low proportion of new proteins which are deposited as functional ECM. It is suggested that cells are pre-embedded in for example collagen gels to increase the steric retention and hence functional deposition. The possibility to induce endogenous ECM formation and tissue regeneration by implantation of growth factors in a carrier material was investigated. Bone morphogenetic protein-2 (BMP-2) is a growth factor known to be involved in growth and differentiation of bone and cartilage tissue. The BMP-2 processing and secretion was examined in two cell systems representing endochondral (chondrocytes) and intramembranous (mesenchymal stem cells) bone formation. It was discovered that chondrocytes are more efficient in producing BMP-2 compared to MSC. The role of the antagonist noggin was also investigated and was found to affect the stability of BMP-2 and modulate its effect. Finally, an injectable gel of the ECM component hyaluronan has been evaluated as delivery vehicle in cartilage regeneration. The hyaluronan hydrogel system showed promising results as a versatile biomaterial for cartilage regeneration, could easily be placed intraarticulary and can be used for both cell based and cell free therapies.

The aim of the project was to develop a method to measure and studythe degree of activation of the negative electrode (MH) in a NiMH battery.This was done by characterization of the gases produced during charge of a battery – O2 and H2 – using a Gas Chromatograph. The current applied in the very first charge of the battery was varied in order to examine how this affects the gas evolution. In the developed method, batteries were charged to 8Ah with 9A, after which a gas sample was taken and analyzed with Gas Chromatography. An additional goal was to use the method to examine the difference in activation between virgin and recycled negative electrode material. A module charged stepwise with 0.07C followed by 0.2C had the lowest share of H2 after two cycles, indicated best activation. However, a higher amount of H2 in the beginning of the activation process could possibly enhance the degree of activation during the following cycles. The method indicated that the module with recycled MH was better activated than the virgin MH. To improve the technique, repeated measurements to get better statistics should be done. Gas samples should be taken at dV/dt=0 in order to take samples at same SoC. The charge current should be adjusted so that the same C rate is always used. This would make the results easier to interpret.

Electrochemical systems, which rely on coupled phenomena of the chemical change and electricity, have been utilized for development an interface between biological systems and conventional electronics.  The development and detailed understanding of the operation mechanism of such interfaces have a great importance to many fields within life science and conventional electronics. Conducting polymer materials are extensively used as a building block in various applications due to their ability to transduce chemical signal to electrical one and vice versa. The mechanism of the coupling between the mass and charge transfer in electrochemical systems, and particularly in conductive polymer based system, is highly complex and depends on various physical and chemical properties of the materials composing the system of interest. The aims of this thesis have been to study electrochemical systems including conductive polymer based systems and provide knowledge for future development of the devices, which can operate with both chemical and electrical signals. Within the thesis, we studied the operation mechanism of ion bipolar junction transistor (IBJT), which have been previously utilized to modulate delivery of charged molecules. We analysed the different operation modes of IBJT and transition between them on the basis of detailed concentration and potential profiles provided by the model. We also performed investigation of capacitive charging in conductive PEDOT:PSS polymer electrode. We demonstrated that capacitive charging of PEDOT:PSS electrode at the cyclic voltammetry, can be understood within a modified Nernst-Planck-Poisson formalism for two phase system in terms of the coupled ion-electron diffusion and migration without invoking the assumption of any redox reactions. Further, we studied electronic structure and optical properties of a self-doped p-type conducting polymer, which can polymerize itself along the stem of the plants. We performed ab initio calculations for this system in undoped, polaron and bipolaron electronic states. Comparison with experimental data confirmed the formation of undoped or bipolaron states in polymer film depending on applied biases. Finally, we performed simulation of the reduction-oxidation reaction at microband array electrodes. We showed that faradaic current density at microband array electrodes increases due to non-linear mass transport on the microscale compared to the corresponding macroscale systems.  The studied microband array electrode was used for developing a laccase-based microband biosensor. The biosensor revealed improved analytical performance, and was utilized for in situ phenol detection.

The chemical bond – a corner stone in science and a prerequisite for life – is the focus of this thesis. Fundamental and applied aspects of chemical bonding are covered including the development of new computational methods for the characterization and rationalization of chemical interactions. The thesis also covers the study of corrosion of copper-based materials. The latter is motivated by the proposed use of copper as encapsulating material for spent nuclear fuel in Sweden. In close collaboration with experimental groups, state-of-the-art computational methods were employed for the study of chemistry at the atomic scale. First, oxidation of nanoparticulate copper was examined in anoxic aqueous media in order to better understand the copper-water thermodynamics in relation to the corrosion of copper material under oxygen free conditions. With a similar ambition, the water-cuprite interface was investigated with regards to its chemical composition and reactivity. This was compared to the behavior of methanol and hydrogen sulfide at the cuprite surface. An overall ambition during the development of computational methods for the analysis of chemical bonding was to bridge the gap between molecular and materials chemistry. Theory and results are thus presented and applied in both a molecular and a solid-state framework. A new property, the local electron attachment energy, for the characterization of a compound’s local electrophilicity was introduced. Together with the surface electrostatic potential, the new property predicts and rationalizes regioselectivity and trends of molecular reactions, and interactions on metal and oxide nanoparticles and extended surfaces. Detailed atomistic understanding of chemical processes is a prerequisite for the efficient development of chemistry. We therefore envisage that the results of this thesis will find widespread use in areas such as heterogeneous catalysis, drug discovery, and nanotechnology. / Den kemiska bindningen – en hörnsten inom naturvetenskapen och oumbärlig för allt liv – är det centrala temat i den här avhandlingen. Både grundläggande och tillämpade aspekter behandlas. Detta inkluderar utvecklingen av nya beräkningsmetoder för förståelse och karaktärisering av kemiska interaktioner. Dessutom behandlas korrosion av kopparbaserade material. Det sistnämnda är motiverat av förslaget att använda koppar som inkapslingsmaterial för hanteringen av kärnavfall i Sverige. Kvantkemiska beräkningsmetoder enligt state-of-the-art har använts för att studera kemi på atomnivå, detta i nära sammabete med experimentella grupper. Initialt studerades oxidation av kopparnanopartiklar under syrgasfria och vattenrika förhållanden. Detta för att bättre kartlägga koppar-vattensystemets termodynamik. Av samma orsak detaljstuderades även gränsskiktet mellan vatten och kuprit med fokus på dess kemiska sammansättning och reaktivitet. Resultaten har jämförts med metanols och vätesulfids kemiska beteende på ytan av kuprit. En övergripande målsättningen under arbetet med att utveckla nya beräkningsbaserade analysverktyg för kemiska bindningar har varit att överbrygga gapet mellan molekylär- och materialkemi. Därför presenteras teoretiska aspekter samt tillämpningar från både ett molekylärt samt ett fast-fas perspektiv. En ny deskriptor för karaktärisering av föreningars lokala elektrofilicitet har introducerats – den lokala elektronadditionsenergin. Tillsammans med den elektrostatiska potentialen uppvisar den nya deskriptorn förmåga att förutsäga samt förklara regioselektivitet och trender för molekylära reaktioner, och för interaktioner på metal- och oxidbaserade nanopartiklar och ytor. En detaljerad förståelse av kemiska processer på atomnivå är en nödvändighet för ett effektivt utvecklande av kemivetenskapen. Vi förutspår därför att resultaten från den här avhandlingen kommer att få omfattande användning inom områden som heterogen katalys, läkemedelsdesign och nanoteknologi. / <p>QC 20170829</p>

This dissertation focused on development and utilization of numerical and experimental approaches to improve the CFD modeling of fluidization flow of cohesive micron size particles. The specific objectives of this research were: (1) Developing a cluster prediction mechanism applicable to Two-Fluid Modeling (TFM) of gas-solid systems (2) Developing more accurate drag models for Two-Fluid Modeling (TFM) of gas-solid fluidization flow with the presence of cohesive interparticle forces (3) using the developed model to explore the improvement of accuracy of TFM in simulation of fluidization flow of cohesive powders (4) Understanding the causes and influential factor which led to improvements and quantification of improvements (5) Gathering data from a fast fluidization flow and use these data for benchmark validations. Simulation results with two developed cluster-aware drag models showed that cluster prediction could effectively influence the results in both the first and second cluster-aware models. It was proven that improvement of accuracy of TFM modeling using three versions of the first hybrid model was significant and the best improvements were obtained by using the smallest values of the switch parameter which led to capturing the smallest chances of cluster prediction. In the case of the second hybrid model, dependence of critical model parameter on only Reynolds number led to the fact that improvement of accuracy was significant only in dense section of the fluidized bed. This finding may suggest that a more sophisticated particle resolved DNS model, which can span wide range of solid volume fraction, can be used in the formulation of the cluster-aware drag model. The results of experiment suing high speed imaging indicated the presence of particle clusters in the fluidization flow of FCC inside the riser of FIU-CFB facility. In addition, pressure data was successfully captured along the fluidization column of the facility and used as benchmark validation data for the second hybrid model developed in the present dissertation. It was shown the second hybrid model could predict the pressure data in the dense section of the fluidization column with better accuracy.

The development of solution-processable semiconducting polymers has brought mankind’s long-sought dream of plastic electronics to fruition. Their potential in the manufacturing of lightweight, flexible yet robust, and biocompatible electronics has spurred their use in organic transistors, photovoltaics, electrochromic devices, batteries, and sensors for wearable electronics. Yet, despite the successful engineering of semiconducting polymers, we do not fully understand their molecular behavior and how it influences their doping (oxidation/reduction) properties. This is especially true for donor-acceptor (D-A) p-systems which have proven to be very efficient at tuning the electronic properties of organic semiconductors. Historically, chain-length dependent studies have been essential in uncovering the relationship between the molecular structure and polymer properties. Discussed here is the systematic investigation of a complete D-A molecular series composed of monodispersed and well-defined conjugated molecules ranging from oligomer (n=3-21) to polymer scale lengths. Structure-property relationships are established between the molecular structure, chain conformation, and redox-active opto-electronic properties for the molecular series in solution. This research reveals a rod-to-coil transition at the 15 unit chain length, or 4500 Da, in solution. The redox-active optical and electronic properties are investigated as a function of increasing chain-length, giving insight into the nature of charge carriers in a D-A conjugated system. This research aids in understanding the solution behavior of conjugated organic materials. <br>

Perovskite based materials have great potentials for various energy applications and the search for new materials for uses in SOFCs has largely been concentrated to this class of compounds. In this search, we have studied perovskite phases in the system La2Co1+z(Ti1-xMgx)1-zO6, with 0  x 0.9 and z = 0.0, 0.2, 0.4, 0.6. Crystal structures were characterized by XRD and, for selected compositions, also by NPD and SAED. They exhibit with increasing x, as well as increasing z, a progressive increase in symmetry from monoclinic to orthorhombic to rhombohedral. The main focus in this work has been on the investigation of structure-property relations for compositions with 0.0 x 0.5 and z = 0. The nominal oxidation state of Co increases for these with increasing x, from Co2+ for x = 0 to Co3+ for x = 0.5. Magnetic measurements and XANES studies showed that the average spin state of Co changes linearly with increasing x, up to x = 0.5, in accordance with varying proportions of Co with two fixed oxidation states, i.e. Co2+ and Co3+. The data suggests that the Co3+ ions have an IS spin state or a mixture of LS and HS spin states for all compositions with nominally only Co2+ and Co3+ ions, possibly with the exception of the composition with x = 0.1, 0.2 and z = 0, for which the data indicate that the spin state might be HS. The XANES data indicate furthermore that for the perovskite phases with z = 0 and x &gt; 0.5, which in the absence of O atom vacancies contain formally Co4+, the highest oxidation state of Co is Co3+, implying that the substitution of Ti4+ by Mg2+ for x ³ 0.5 effects an oxidation of O2- ions rather than an oxidation of Co3+ ions. The thermal expansion was found to increase nearly linearly with increasing oxidation state of Co. This agrees well with findings in previous studies and is attributable to an increase in the ionic radius of Co3+ ions with increasing temperature, due to a thermal excitation from a LS to IS or LS/HS spin states. High temperature electronic conductivity measurements indicate that the electronic conductivity increases with an increase of both relative and absolute amount of Co3+. The latter can be attributed to an increase in the number of Co-O-Co connections. Additional high temperature magnetic measurements for selected samples, whose susceptibilities did not follow a Curie law behaviour up to room temperature, showed effective magnetic moments that did approach plateaus even at high temperatures (900 K). Interpretations of these data are, however, hindered by the samples losing oxygen during the applied heating-cooling cycle. The present study has shown that the investigated system is suitable for further studies, of more fundamental character, which could provide further insight of the structure-property relationships that depend on the oxidation state of Co. / Studies of cobalt based perovskites for cathode materials in solid oxide fuel cells.

Active layer morphology of polymer-based solar cells plays an important role in improving power conversion efficiency (PCE). In this thesis, the focus is to improve the device efficiency of polymer-based solar cells. In the first objective, active layer morphology of polymer-solar cells was optimized though a novel solvent annealing technique. The second objective was to explore the possibility of replacing the highly sensitive aluminum cathode layer with a low-cost and stable alternative, copper metal. Large scale manufacturing of these solar cells is also explored using roll-to-roll printing techniques. Poly (3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl (PCBM) were used as the active layer blend for fabricating the solar cell devices using bulk heterojunction (BHJ), which is a blend of a donor polymer and an acceptor material. Blends of the donor polymer, P3HT and acceptor, PCBM were cast using spin coating and the resulting active layers were solvent annealed with dichlorobenzene in an inert atmosphere. Solvent annealed devices showed improved morphology with nano-phase segregation revealed by atomic force microscopy (AFM) analysis. The roughness of the active layer was found to be 6.5 nm. The nano-phase segregation was attributed to PCBM clusters and P3HT domains being arranged under the solvent annealing conditions. These test devices showed PCE up to 9.2 % with current density of 32.32 mA/cm2, which is the highest PCE reported to date for a P3HT-PCBM based system. Copper was deposited instead of the traditional aluminum for device fabrication. We were able to achieve similar PCEs with copper-based devices. Conductivity measurements were done on thermally deposited copper films using the two-probe method. Further, for these two configurations, PCE and other photovoltaic parameters were compared. Finally, we studied new techniques of large scale fabrication such as ultrasonic spray coating, screen-printing, and intense pulse light sintering, using the facilities at the Conn Center for Renewable Energy Research at the University of Louisville. In this study, prototype devices were fabricated on flexible ITO coated plastics. Sintering greatly improved the conductivity of the copper nano-ink cathode layer. We will explore this technique’s application to large-scale fabrication of solar cell devices in the future work.

A fairly new technology used to produce metallic components is powder metallurgy (PM). Among the advantages with this technique are decreased cost of production for complex-shaped parts, new alloys are made possible, reduced end processing, less material loss, and vibrational damping effects. The downside is the number of pores created which can alter the tribological properties of the material. The focus of this report is to investigate how lean PM steel behaves under tribological contacts.  Friction and wear will be investigated using a pin-on-disc setup to mimic the sliding part of a gear tooth mesh. Previous studies show that the amount of wear, and if the wear increases or decreases with increased density is dependent on the degree of porosity and the pore size. This means that the wear might be minimized by optimizing the number of pores in the material and their shape and size. The result of this study shows that the friction coefficient decreases with increasing density. The wear coefficient show signs of the same correlations but further tests are needed. The main wear comes from adhesive wear, with signs of abrasive wear. The amount of abrasive wear seems to increase with an increase in density, supporting previous studies claiming that pores can trap wear debris and decrease the number of abrasive particles in the contact.