<p>Cladophora cellulose polypyrrole composites are recognized as potential biomaterials with future applications in hemodialysis. In this project conductive Cladophora cellulose-polypyrrole (clad-ppy) composites were prepared using two different oxidizing agents: iron (III) chloride and phosphomolybdic acid (PMo). Cyclic voltammetry, conductivity and Specific surface area measurements were done to characterize the synthesized composites. Furthermore in vitro blood compatibility studies were performed. Whole blood was incubated with clad-ppy membranes and then blood was analyzed for platelet number reduction and complement activation products (C3a and sC5b-9). Clad-ppy with Iron (III) chloride membranes were found to be superior in terms of conductivity and surface area while Clad-ppy with PMo membranes were found to provoke less blood activation. The results indicated that each oxidizing agent gave distinct properties to the composite material.</p>

<p>New smart drugs demand new smart drug delivery systems and also new smart analysis methods for the drug delivery process and material characterization. This thesis contributes to the field by introducing a new electrodynamic approach for studying the drug diffusion proc-esses as well as the formation of a new type of drug delivery systems, the so called mesoporous nano excipients.</p><p>Drug diffusion processes from different pharmaceutical materials were examined. The transport of charged drug substances was investigated by electrodynamic methods; either as a release process governed by diffusion using the alternating ionic current method or by applying a voltage, sinusoidal or dc, to force the drug ions to move in an electric field.</p><p>Temperature-dependent drug release from microcrystalline cellulose tablets was examined in order to extract information about the diffu-sion process. Percolation theory was also employed to binary mixtures of an insoluble and electrically insulating matrix material together with a soluble and ionic conducting drug. Further, dielectric spectros-copy was proven to be a powerful method for examining the state of vesicle formation of drug and surfactant molecules in a carbopol gel. Finally, a new potential class of pharmaceutical materials were exam-ined, namely the AMS-n mesoporous materials, showing that the al-ternating ionic current method is powerful both in the study of the synthesis of and in the release process from these. </p>

Cladophora cellulose polypyrrole composites are recognized as potential biomaterials with future applications in hemodialysis. In this project conductive Cladophora cellulose-polypyrrole (clad-ppy) composites were prepared using two different oxidizing agents: iron (III) chloride and phosphomolybdic acid (PMo). Cyclic voltammetry, conductivity and Specific surface area measurements were done to characterize the synthesized composites. Furthermore in vitro blood compatibility studies were performed. Whole blood was incubated with clad-ppy membranes and then blood was analyzed for platelet number reduction and complement activation products (C3a and sC5b-9). Clad-ppy with Iron (III) chloride membranes were found to be superior in terms of conductivity and surface area while Clad-ppy with PMo membranes were found to provoke less blood activation. The results indicated that each oxidizing agent gave distinct properties to the composite material.

New smart drugs demand new smart drug delivery systems and also new smart analysis methods for the drug delivery process and material characterization. This thesis contributes to the field by introducing a new electrodynamic approach for studying the drug diffusion proc-esses as well as the formation of a new type of drug delivery systems, the so called mesoporous nano excipients. Drug diffusion processes from different pharmaceutical materials were examined. The transport of charged drug substances was investigated by electrodynamic methods; either as a release process governed by diffusion using the alternating ionic current method or by applying a voltage, sinusoidal or dc, to force the drug ions to move in an electric field. Temperature-dependent drug release from microcrystalline cellulose tablets was examined in order to extract information about the diffu-sion process. Percolation theory was also employed to binary mixtures of an insoluble and electrically insulating matrix material together with a soluble and ionic conducting drug. Further, dielectric spectros-copy was proven to be a powerful method for examining the state of vesicle formation of drug and surfactant molecules in a carbopol gel. Finally, a new potential class of pharmaceutical materials were exam-ined, namely the AMS-n mesoporous materials, showing that the al-ternating ionic current method is powerful both in the study of the synthesis of and in the release process from these.

Ferroelectric oxides are a group of advanced electronic materials with a wide variety of properties useful in applications such as memory devices, resonators and filters, infrared sensors, microelectromechanical systems, and optical waveguides and modulators. Among the oxide perovskite-structured ferroelectric thin film materials, sodium potassium niobate or Na0.5K0.5NbO3 (NKN) has recently emerged as one of the most promising materials in radio frequency (rf) and microwave applications due to high dielectric tenability and low dielectric loss. This thesis presents results on growth and structural, optical, and electrical characterization of NKN thin films. The films were deposited by rf-magnetron sputtering of a stoichiometric, high density, ceramic Na0.5K0.5NbO3 target onto single crystal LaAlO3 (LAO), Al2O3 (sapphire), SrTiO3, and Nd:YAlO3, and polycrystalline Pt80Ir20 substrates. By x-ray diffractometry, NKN films on c-axis oriented LaAlO3, SrTiO3 and Nd:YAlO3 substrates were found to grow epitaxially, whereas films on r-cut sapphire and polycrystalline Pt80Ir20 substrates were found to be preferentially (00l) oriented. The surface morphology was explored using atomic force microscopy. Optical and waveguiding properties of the Na0.5K0.5NbO3/substrate heterostructures were characterized using prism-coupling technique. Sharp and distinguishable transverse magnetic and electric propagation modes were observed for NKN thicknesses up to 2.0 μm. The extraordinary and ordinary refractive indices were calculated together with the birefringence of the NKN material. The electro-optic effect in transverse geometry was measured in transmission, where the effective linear electro-optic response was determined to reff = 28 pm/V for NKN/Al2O3 with an applied dc field up to 18 kV/cm. The ferroelectric state in NKN films on Pt80Ir20 at room temperature was indicated by a polarization loop with saturated polarization as high as 33.4 μC/cm2 at 700 kV/cm, remnant polarization of 10 μC/cm2, and coercive field of 90 kV/cm. Current-voltage characteristics of vertical Au/NKN/PtIr capacitive cells and planar Au/NKN/LAO interdigital capacitors (IDCs) showed very good insulating properties, with the leakage current density for an NKN IDC on the order of 30 nA/cm2 at 400 kV/cm. Rf dielectric spectroscopy demonstrated low loss, low frequency dispersion, and high voltage tunability. At 1 MHz, NKN/LAO showed a dissipation factor tan δ = 0.010 and a tunability of 16.5 % at 200 kV/cm. For the same structure the frequency dispersion was Δεr = 8.5 % between 1 kHz and 1 MHz. / QC 20100928

<p>The urgent need for new, sustainable energy source intrigues scientists to provide the solution by developing new technology. Polymer solar cell appears to be the most promising candidate for its low cost, flexibility, and massive producibility. Novel polymers have been constantly synthesized and investigated, while the use of PCBM as acceptor seems to be the universal choice. Here, we studied the use of four dierent fullerene derivatives - [60]PCBM, [70]PCBM, and their bisadduct analogues - as acceptor in APFO-3 solar cells. A series of investigations were performed to study how the processing parameters - blend ratio, spin speed, and choice of solvent - influence the device performance. Using bisadduct fullerenes results in an enhanced Voc, as predicted by the up-shift of energy levels, but a strongly reduced Jsc, hence a poor PCE. Photoluminescence study indicates that all APFO-3:fullerene devices are limited by the inefficient dissociation of fullerene excitations, while it becomes more influential when bisadduct fullerenes were used as acceptor. The best device in this study was fabricated by using [70]PCBM as acceptor and chlorobenzene as solvent, exhibits a PCE of 2.9%, for the strong absorption, ne morphology, and comparatively strong driving force.</p>

The urgent need for new, sustainable energy source intrigues scientists to provide the solution by developing new technology. Polymer solar cell appears to be the most promising candidate for its low cost, flexibility, and massive producibility. Novel polymers have been constantly synthesized and investigated, while the use of PCBM as acceptor seems to be the universal choice. Here, we studied the use of four dierent fullerene derivatives - [60]PCBM, [70]PCBM, and their bisadduct analogues - as acceptor in APFO-3 solar cells. A series of investigations were performed to study how the processing parameters - blend ratio, spin speed, and choice of solvent - influence the device performance. Using bisadduct fullerenes results in an enhanced Voc, as predicted by the up-shift of energy levels, but a strongly reduced Jsc, hence a poor PCE. Photoluminescence study indicates that all APFO-3:fullerene devices are limited by the inefficient dissociation of fullerene excitations, while it becomes more influential when bisadduct fullerenes were used as acceptor. The best device in this study was fabricated by using [70]PCBM as acceptor and chlorobenzene as solvent, exhibits a PCE of 2.9%, for the strong absorption, ne morphology, and comparatively strong driving force.

<!--[if !mso]> <object classid="clsid:38481807-CA0E-42D2-BF39-B33AF135CC4D" id=ieooui></object><mce:style><! st1\:*{behavior:url(#ieooui) } --> The present work was initiated to study the synthesis and properties of lanthanum gallate based oxides as intermediate temperature electrolyte for solid oxide fuel cells. The wet chemical method, polymer complexing route, was used to prepare the precursor powders. To further investigate the polymer complexing method, it was also applied to the preparation of lanthanum aluminate based oxides.   Single perovskite phase La0.8Sr0.2Ga0.83Mg0.17O2.815 can be prepared by the polymer complexing method using PVA as complexing agent. The thermal decomposition of the precursor powder undergoes three stages. While complete decomposition of the precursor is obtained at 1000°C. Further investigation of LaGaO3 doped with various amounts Sr or/and Mg was conducted. Three secondary phases were identified by X-ray diffraction, e.g. LaSrGaO4, LaSrGa3O7 and La4Ga2O9. The relative amount of these secondary phases depends on the doping compositions. Sr doping produced more Sr rich secondary phases with increasing content, while enhanced solid solubility was observed with Mg addition. Sintered samples showed dense microstructures with well-developed equiaxed grains, and the secondary phases were mainly in the grain boundaries. The oxygen ionic conductivity was enhanced by doping with Sr and Mg. Mg doping showed the increased activation energy of conductivity.   Preliminary study showed that the lanthanum gallate and ceria composite electrolyte is mainly fluorite CeO2 phase after sintering. The minority secondary phase, Sm3Ga5O12, was also detected by XRD. The composite electrolyte showed superior electrical performance. It exhibited the highest conductivity in the temperature range of 250–600°C, compared with lanthanum gallate and ceria specimens.   The phase pure perovskite La0.9Sr0.1Al0.85Mg0.1Co0.05O2.875 powders can easily be obtained by the polymer method using PVA as complexing agent. No secondary phase was detected after calcination at various temperatures (500–1100°C). The fully crystallized LaAlO3 phase was prepared after calcination at 900°C. Meanwhile the secondary phases were difficult to eliminate in the Sr- and Mg- doped LaGaO3 powder prepared by the same polymer method. It is thus concluded that the polymer, PVA in this work, provides more homogeneous mixing for cations of lanthanum aluminate based oxides, compared with the one for doped lanthanum gallate.   The influence of different complexing agents, e.g. PVA and PEG, was investigated in the synthesis of lanthanum aluminate powders. Minority impurity La2O3 existed in the PEG powder, but it could be eliminated after sintering at high temperatures. Although the pure phase LaAlO3 can be easily obtained in PVA powders calcined at 950°C, more seriously aggregated particles existed. PEG showed advantages over PVA in terms of better densification and microstructure control in the sintered products. To select proper polymers in complex oxide synthesis, the agglomeration and morphology of the powder are the most important factors to be considered. / QC 20100727

This thesis focuses on the application of nanocrystalline transition metal oxide TiO2, WO3 and NiO thin films in new “green” building technologies. Specifically, their physicochemical properties in photocatalytic, self-cleaning and gas sensing applications are studied. There is an intimate connection between comfort issues, health, with connections to energy efficiency, leading to a need for intelligent building materials and green architecture. The importance of good indoor environment is augmented by the fact that modern man in developed countries spends some 90 % of his time inside buildings and vehicles. Poor air quality may lead to discomfort of the person inhabiting a building and in ultimately cause adverse health effects. Thin films of nanocrystalline TiO2 were prepared using reactive DC magnetron sputtering. Crystalline mesoporous films of WO3 and NiO were prepared using advanced gas deposition technique (AGD). The crystal structure, morphology, optical and chemical properties of the films were characterized by using grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM), UV/Vis spectroscopy and X-ray photoelectron spectroscopy (XPS), respectively. The photocatalytic properties and adsorption of both organic and inorganic molecules on pure and functionalized films were probed by in situ Fourier transform infrared spectroscopy (FTIR). The gas sensing properties of sensors based on TiO2, WO3 and NiO were investigated by conductivity measurements and noise spectroscopy. It was found for the first time that NiO based thin film sensors can be used to detect H2S and NO2 at low temperatures – down to room temperature. Hybrid WO3 sensors functionalized with multiwalled carbon nanotubes (MWCNTs) were used to detect NO2, CO and NH3 gases. These hybrid gas sensors show improved recovery properties compared to unmodified WO3 sensors. TiO2 based gas sensors were able to detect low concentrations of H2S by noise spectroscopy provided that the sensors were irradiated by UV light. Furthermore we show that sulphur is photo-fixated in crystalline TiO2 films upon simultaneous SO2 gas exposure and UV irradiation. Studies of the kinetics and identity of the photo-fixated sulphur complexes show that these are formed by photo-induced reactions between oxygen and SO2 at oxygen surface vacancy sites in TiO2. The sulphur modified TiO2 films show interesting self-cleaning properties compared to the pure films. / Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 739

Within the field of neuroprosthetics the possibility to use implanted electrodes for communication with the nervous system is explored. Much effort is put into the material aspects of the electrode implant to increase charge injection capacity, suppress foreign body response and build micro sized electrode arrays allowing close contact with neurons. Conducting polymers, in particular poly(3,4-ethylene dioxythiophene) (PEDOT), have been suggested as materials highly interesting for such neural communication electrodes. The possibility to tailor the material both mechanically and biochemically to suit specific applications, is a substantial benefit with polymers when compared to metals. PEDOT also have hybrid charge transfer properties, including both electronic and ionic conduction, which allow for highly efficient charge injection.   Part of this thesis describes a method of tailoring PEDOT through exchanging the counter ion used in electropolymerisation process. Commonly used surfactants can thereby be excluded and instead, different biomolecules can be incorporated into the polymer. The electrochemical characteristics of the polymer film depend on the ion. PEDOT electropolymerised with heparin was here determined to have the most advantageous properties. In vitro methods were applied to confirm non-cytotoxicity of the formed PEDOT:biomolecular composites. In addition, biocompatibility was affirmed for PEDOT:heparin by evaluation of inflammatory response and neuron density when implanted in rodent cortex.   One advantage with PEDOT often stated, is its high stability compared to other conducting polymers. A battery of tests simulating the biological environment was therefore applied to investigate this stability, and especially the influence of the incorporated heparin. These tests showed that there was a decline in the electroactivity of PEDOT over time. This also applied in phosphate buffered saline at body temperature and in the absence of other stressors. The time course of degradation also differed depending on whether the counter ion was the surfactant polystyrene sulphonate or heparin, with a slightly better stability for the former.   One possibility with PEDOT, often overlooked for biological applications, is the use of its semi conducting properties in order to include logic functions in the implant. This thesis presents the concept of using PEDOT electrochemical transistors to construct textile electrode arrays with in-built multiplexing. Using the electrolyte mediated interaction between adjacent PEDOT coated fibres to switch the polymer coat between conducting and non conducting states, then transistor function can be included in the conducting textile. Analogue circuit simulations based on experimentally found transistor characteristics proved the feasibility of these textile arrays. Developments of better polymer coatings, electrolytes and encapsulation techniques for this technology, were also identified to be essential steps in order to make these devices truly useful.   In summary, this work shows the potential of PEDOT to improve neural interfaces in several ways. Some weaknesses of the polymer and the polymer electronics are presented and this, together with the epidemiological data, should point in the direction for future studies within this field. / QC 20100623