In recent years, nanostructured materials incorporated with inorganic particles and polymers have attracted attention for simultaneous multifunctional biomedical applications. This thesis summarized three works, which are preparation of mesoporous silica coated superparamagnetic iron oxide (Fe3O4@mSiO2) nanoparticles (NPs) as magnetic resonance imaging T2 contrast agents, polymer grafted Fe3O4@mSiO2 NPs response to temperature change, synthesis and biocompatibility evaluation of high aspect ratio (AR) gold nanorods. Monodisperse Fe3O4@mSiO2 NPs have been prepared through a sol-gel process. The coating thickness and particle sizes can be precisely controlled by varying the synthesis parameters. Impact of surface coatings on magnetometric and relaxometric properties of Fe3O4 NPs is studied. The efficiency of these contrast agents, evaluated by MR relaxivities ratio (r2/r1), is much higher than that of the commercial ones. This coating-thickness dependent relaxation behavior is explained due to the effects of mSiO2 coatings on water exclusion. Multifunctional core-shell composite NPs have been developed by growing thermo-sensitive poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAAm-co-AAm)) on Fe3O4@mSiO2 NPs through free radical polymerization. Their phase transition behavior is studied, and their lower critical solution temperature (LCST) can be subtly tuned from ca. 34 to ca. 42 °C, suitable for further in vivo applications. A seedless surfactant-mediated protocol has been applied for synthesis of high AR gold nanorods with the additive of HNO3. A growth mechanism based on the effect of nitrate ions on surfactant micelle elongation and Ostwald ripening process is proposed. The biocompatibility of high AR nanorods was evaluated on primary human monocyte derived dendritic cells (MDDCs). Their minor effects on viability and immune regulatory markers support further development for medical applications. / QC 20110701

This report aims to study the degradation of poly(trimethylene carbonate) (PTMC) caused by the enzyme carboxylesterase in vitro. As well as to characterise polymer blends of f-BTI2g-TVTCN and poly(3-hydroxybutyric acid) as core components for organic electrochemical transistors (OETCs). This is to assess the suitability of these polymers in biodegradable biosensors. The degradation study of PTMC showed a lack of degradation in contrast to previous studies performed on the material; previous studies recorded a mass loss of between (5-8)% after two months. The cause for this discrepancy is still unknown but the evidence points to both systematic faults in the gravimetric analysis as well as random errors found in the equipment. The OECT showed that increasing the PHB fraction in the polymer blend resulted in a higher output. The most stable device consisted of a 1:6 blend of f-BTI2g-TVTCN to PHB. Fewer tests were conducted on the 1:10 blend because two devices were damaged during the experiment. The statistical impact of the smaller sample size cannot be overstated so further testing should be conducted to verify the results.

För att skapa ett hållbart samhälle måste material av fossilt ursprung ersättas med förnyelsebara och miljövänliga alternativ. Ett sådant alternativ är cellulosa från vedfibrer, som har stor potential att kunna ersätta många fossila material i framtiden. För att kunna uppnå detta behöver cellulosans egenskaper först modifieras för att passa olika ändamål och helt kunna ersätta fossila alternativ. I detta kandidatexamensprojekt modifierades blekt sulfatmassa, oblekt sulfatmassa, dissolvingmassa och kemitermomekanisk massa (CTMP) genom att introducera kvartära aminer med hjälp av två olika reagens, 2,3-epoxypropyltrimetylammoniumklorid (EPTMAC) och 3-kloro-2-hydroxypropyltrimetylammoniumklorid (CHPTAC). Under projektet undersöktes reagensens reaktionseffektivitet för de olika massorna genom att mäta substitutionsgraden (DS), hur förbehandling i form av torkning och malning påverkar modifieringsreaktionen och den modifierade massans egenskaper, utgångsmassornas svällningsegenskaper, samt mekaniska egenskaper som e-modul, brottstyrka och brottöjning hos pappersark tillverkade av modifierad massa. Resultaten från studien visar att det reaktionseffektivaste reagenset var CHPTAC som gav upphov till en genomgående högre effektivitet än samtliga modifieringar med EPTMAC, men att effektiviteten för respektive reagens är mindre beroende av pappersmassans komposition. Modifiering resulterade i att alla massor fick högre styrka i form av e-modul, brottstyrka och brottöjning. De mekaniska egenskaperna följde inte samma trend som substitutionsgraderna, vilket var oväntat. För att kunna dra mer pålitliga slutsatser skulle ytterligare studier behöva genomföras, inklusive upprepade modifieringar med varierande mängd reagens, mekaniska tester samt analys av ytterligare egenskaper som fibrernas ytor, kristallstruktur och längden på cellulosafibrerna.

In this project, solid sulphur based Li3PS4 electrolytes doped with Li4SiO4 were synthesised using two methods. In method A, a bought β-Li3PS4 electrolyte from Nei Corp was doped with 5 mole per cent Li4SiO4, resulting in a glass-ceramic electrolyte. In method B, the electrolyte was synthesised using 5Li4SiO4-95(75Li2S-25P2S5), resulting in a glassy material. In addition, a reference was synthesised using 75Li2S-25P2S5. Ball milling was the method of choice to dope the glass ceramic electrolyte and synthesise the glassy electrolyte. The dopant Li4SiO4 was synthesised using the chemicals SiO2 and Li2CO3. All samples were analysed using Raman, XPS, XRD, and EIS. In the end, it was found that doping the bought β-Li3PS4electrolyte with Li4SiO4 increased the ionic conductivity. While introducing Li4SiO4 to the glassy electrolyte lowered the ionic conductivity. The increase in ionic conductivity in the glass ceramic electrolyte was partly attributed to the increase in amorphous content, which happened when it was ball-milled and suppressed P-S-P bonds. The decrease in ionic conductivity that happened when doping the glassy material, is most likely caused by residual Li2S that seems unable to react due to the dopant.

Lithium ion batteries (LIBs) are widely used for storing and converting chemical energy into electrical energy. During battery operation, lithium ions move between electrode materials, enabling energy storage. However, aging mechanisms like lithium plating can negatively impact battery performance and lifetime. Lithium plating occurs when lithium ions are reduced to metallic lithium on the graphite electrode. The undesired Li plating in LIBs leads to dendrite formation that may puncture the separator, causing internal short-circuit and ultimately thermal runaway. This study aims to investigate the internal processes of LIBs during charge and discharge. Two analysis methods are employed: online electrochemical mass spectrometry (OEMS) and acoustic emission monitoring (AEM). OEMS is a gas analysis technique that combines electrochemical measurements with mass spectrometry to provide real-time testing of cells. OEMS allows identifying and quantifying gas evolution/consumption of chemical species. AE is a diagnostic tool, offering monitoring the health of LIBs through detection and characterisation of stress waves produced by parasitic mechano-electrochemical events. The results indicates that the formation of SEI thin film layer, generated gases like hydrogen and ethylene, while consuming carbon dioxide. During induced lithium plating, hydrogen and carbon dioxide were consumed, and ethylene gas was produced, due to new SEI film formation process. The acoustic emission analysis indicated that lithium plating was an active process, whereas SEI formation was less AE active. Further research is needed to understand the relationships and significance of these processes for battery performance and safety. Overall, this study highlighted the importance of investigating aging mechanisms in LIBs to enhance their performance and longevity. By combining OEMS and AE, it was possible to analyse the batteries behaviour during cycling. The evolution of gas and acoustic signals provided insights into the reactions and processes occurring inside the battery during cycling.

No description available.

The in vitro production of ceramic implants used for cranial defect repair can be challenging and complex. In this thesis, a raw material in such a production has been mapped in order to optimize the production process. The current production leaves variations in the handling properties of the calcium phosphate cement (CPC), such as the viscosity and setting performance. The problems originate from the in-house recrystallization of the raw material monocalcium phosphate monohydrate (MCPM) with a 70% ethanol solution. The treatment of MCPM is strongly dependent on the relative humidity and the current process is not reliable and leaves unwanted fluctuations in the quality of MCPM. Various material and process parameters were investigated to get a deeper knowledge of MCPM in the specific process. The mapping resulted in new information about how the MCPM recrystallizes and how it depends on the evaporation of the ethanol solution during the treatment. Other findings were that the particle size distribution of MCPM is not the only factor controlling the viscosity of the CPC; the density and shape of the MCPM particles may also influence the handling properties. The mapping led to a process optimization suggestion where the amount of ethanol solution is adjusted to the relative humidity during the recrystallization to neutralize the effect of the humidity. The adjustment of ethanol solution volume means the evaporation can be controlled and in theory, constant quality of MCPM can be maintained. Unfortunately, the new method needs additional data to be fully effective but shows great potential.

Due to climate changes and an increasing global temperature, the maritime transport sector has taken upon a mission to reduce their share of greenhouse gas emissions by 50% until 2050. Combustion engines used in ships mainly run on carbon-based fuels, but to achieve the reduction of emissions it is crucial to investigate the possibility of alternative fuels. Ammonia is an alternative fuel with a carbon free chemical composition that shows big potential, with several initiatives to put ammonia driven ship engines on the market in the near future. For ships to be able to run on ammonia fuel, the engine materials have to withstand the corrosive effect of ammonia whilst still ensuring that the motor runs properly. In this study, two piston ring materials are investigated with regards to long-term effects of exposure to ammonia solution. The piston ring materials investigated were comprised of a cast iron substrate covered with either a chromium ceramic coating or a with a cermet coating, the latter also coated with an aluminium-bronze based running in layer on top. The materials were submerged in 25% ammonia solution for different time intervals up to 12 weeks, with a solution change every fourth week. After exposure to ammonia, the materials were tribologically tested in a reciprocal sliding test rig. The surfaces, both inside and outside of the wear tracks, were analysed with SEM and EDS, as well as with CSI. The chromium ceramic coating did not seem to get affected by, or interact chemically, with the ammonia solution. Exposing the material to ammonia did not seemingly affect the tribological properties. However, two different behaviours were observed when analysing the cermet coated samples with a running-in layer of aluminium-bronze. These samples reacted with the ammonia solution in two different ways, resulting in the series being split into two. In both cases precipitates were formed, but the colour changes of the solutions differed for the series. The coatings were also worn differently, as in one case a flattening effect was observed throughout all time intervals, whereas in the other case the worn volume and track depth seemed to increase with exposure to ammonia solution.

Thermoelectrics is the reversible process which transforms a temperature gradient across a material into an external voltage through a phenomenon known as the Seebeck effect. This has resulted in niche applications such as solid-state cooling for electronic and optoelectronic devices which exclude the need for a coolant or any moving parts and long-lasting, maintenance-free radioisotope thermoelectric generators used for deep-space exploration. However, the high price and low efficiency of thermoelectric generators have prompted scientists to search for new materials and/or methods to improve the efficiency of the already existing ones. Thermoelectric efficiency is governed by the dimensionless figure of merit 𝑧𝑇, which depends on the electrical conductivity, thermal conductivity and Seebeck coefficient value of the material and has rarely surpassed unity. In order to address these issues, research conducted on early transition metal nitrides spearheaded by cubic scandium nitride (ScN) thin films showed promising results with high power factors close to 3000 μWm−1K−2 at 500 °C. In this thesis, rock-salt cubic chromium nitride (CrN) deposited in the form of thin films by reactive magnetron sputtering was chosen for its large Seebeck coefficient of approximately -200 μV/K and low thermal conductivity between 2 and 4 Wm−1K−1. The results show that CrN in single crystal form has a low electrical resistivity below 1 mΩcm, a Seebeck coefficient value of -230 μV/K and a power factor close to 5000 μWm−1K−2 at room temperature. These promising results could lead to CrN based thermoelectric modules which are cheaper and more stable compared to traditional thermoelectric material such as bismuth telluride (Bi2Te3) and lead telluride (PbTe). In addition, the project resulting this thesis was prompted to investigate prospective ternary nitrides equivalent to ScN with (hopefully) better thermoelectric properties. Scandium nitride has a relatively high thermal conductivity value (close to 10 Wm−1K−1), resulting in a low 𝑧𝑇. A hypothetical ternary equivalent to ScN may have a similar electronic band structure and large power factor, but with a lower thermal conductivity value leading to better thermoelectric properties. Thus the elements magnesium, titanium, zirconium and hafnium were chosen for this purpose. DFT calculations were used to simulate TiMgN2, ZrMgN2 and HfMgN2. The results show the MeMgN2 stoichiometry to be stable, with two rivaling crystal structures: trigonal NaCrS2 and monoclinic LiUN2. / <p>The series name <em>Linköping Studies in Science and Technology Licentiate Thesis</em> is incorrect. The correct series name is <em>Linköping Studies in Science and Technology Thesis</em>.</p>

<p>ZnO nanoparticles in the size range 2.5–7 nm have been synthesised by a wet chemical method where ZnO particles were grown in basic zinc acetate solution. The optical band gap increases when the size of the particles decreases. An empirical relation between the optical band gap given from absorption measurements, and particle size given from XRD measurements has been developed and compared to other similar relations found in the literature.</p><p>   Time resolved UV-Vis spectroscopy has been used to follow the growth of particles in situ in solution. The data show that the growth mechanism not can be described by a simple Oswald ripening approach and nor by an exclusive agglomeration of smaller clusters into larger particles. The growth mechanism is more likely a combination of the proposed reaction themes. The data also reveal that particle formation do not demand a heating step for formation of the commonly assumed initial cluster Zn₄O(CH₃COO)₆.</p><p>   Steady state fluorescence has been studied as a function of particle size during growth in solution. These measurements confirm what is found in the literature in that the visible fluorescence is shifted to longer wavelengths and loses in intensity as the particles grow. Some picosecond spectroscopy has also been done where the UV fluorescence has been investigated. From these measurements it is apparent that the lifetime of the fluorescence increases with particle size.</p><p>    The phonon spectrum of ZnO has been studied with Raman spectroscopy for a number of different particle sizes. From these measurements it is clear that there is a strong quenching of the phonons due to confinement for the small particles, and the only clearly observed vibration is one at 436 cm^-1 which intensity strongly increases with particle size.   </p>