TiO2 has been extensively studied in the last decades due to its interesting optical and electronic properties, which, combined with low fabrication costs, renders this material very attractive for applications in photovoltaic and photocatalysis. However, the performances of titania in specific device applications were found to be strongly dependent on the synthetic methods selected for its production. The majority of such synthetic procedures rely on the hydrolysis of suitable precursors and often produce an amorphous solid, generally referred as the “amorphous” titanium oxide beside the crystalline titania. In this thesis, we thus set out to investigate amorphous materials produced by the hydrolysis of titanium tetrachlorides and tetraisopropoxide. We show that these amorphous products consists of titanium oxide hydrates, which are relatively stable at room temperature and fully convert into crystalline titania only after extended temperature treatments. We also find that titanium oxide hydrates may display highly desirable characteristic such as a strong photochromic response – especially when placed in a suitable chemical environment. In the following chapter, we then show 3 that hybrid systems can be readily prepared of titanium oxide hydrates with, for instance, macromolecular materials such as poly(vinylalcohol). The amorphous nature of the titanium oxide hydrates allows to introduce more than 90 vol.% of the inorganic species into such systems – compared to 15 vol.% or less when producing hybrids comprising, e.g., crystalline nanoparticles of TiO2. Therefore, materials can be realized that display a refractive index n of at least 2.1, without compromising transparency of the resulting structures. Remarkably, n can not only be adjusted by varying the content of the inorganic species, but also through suitable heat treatments and/or irradiation with UV-light. Potential applications for such new, versatile and tunable optical systems are also discussed in this thesis.

The research conducted is in the field of innovation and focuses on the UK energy sector. The key theme of the study is the transition towards a hydrogen economy with fuel cell technologies at the epicentre and takes into account the relevant scientific, technological, economic and policy issues. In order to provide an understanding of the factors that affect techno-economic transitions to alternative energy systems, the thesis investigates the historical transition processes such as the transition to electrification in the early 1900s and recent transitions to CCGT and renewable energy systems (wind, biofuels and solar) that have taken place since the late 1980s. As the developmental status of hydrogen technologies lay at the heart of these transitions, a thorough analysis of the hydrogen and fuel cell technologies, the R&D requirements, and innovations required in different scientific fields (including materials science) to develop these technologies is conducted. At the same time, as other factors such as sustainability, climate change and security of supply concerns can greatly affect the direction of the transition processes, that includes R&D activities and investment in alternative energy technologies, an overview of these factors is also provided. The analysis employs a new theoretical framework that combines two well established theories in the literature, Techno-economic Transitions and Large Technological Systems. By using this new framework, the technological transition towards a hydrogen energy system can be analysed at three levels, (global, national and local). The analysis is narrowed down to the local level in order to determine the timing of a transition in London and how it can form the foundation for a wider a transition at the national level based on alternative technologies.

No description available.

A detailed electron microscopic study of the morphology and kinetics of crystallization of trans-1,4-polyisoprene with cis isoprene units varying from Of to 19.8 has been carried out. Two crystal structures of trans3., 4-polyisoprene (LIS and in p) were generally observed. In an unstrained film, lamellar single crystals which developed into hedrites, sheaves and spherulites of both crystal modifications were observed. The morphology attained was determined by the growth rate and the nucleation density of the crystals. Electron diffraction study suggests that the lamellar crystals have a chain-folded configuration. In a strained film, a row nucleation morphology was observed LIT and FIMP lamellar crystals were observed to nucleate from the same central 'backbones'. The row nucleation density of the lamellar crystals increases with strain. The growth habits of the lamellar crystals in, both strained and unstrained films were dependent on the film thinness, and on the proximity and the orientation of the neighbouring crystals. Models for the observed growth habits were discussed. The lamellar thickness data agrees with the kinetic theory of chain folding. The lamellar thickness of both crystal structures increases with decreasing degree of supercooling. The fold surface free energies estimated were 45.1 x 10-3 J/n2 and 60.1 x 10-3 J/m2 for the LIT and F ULF crystals of gotta percha respectively. The growth kinetics data of the lamellar crystals determined agrees with the existing theories of crystal growth. At the range of temperature from 400 to 560, the HMF crystal has a faster growth rate than the LMF crystallized at the same temperature. At the same degree of supercooling, the LMF crystal has a faster growth rate. The growth rates of both the LMF and HMF crystals decrease as the cis content on a trans polymer chain increases. With 66 cis units, the growth rate of the isomerized specimen decreased to a value of 1/6 to 1/8 of that for gutta percha (0f cis), whereas in cis-polyisoprene, the growth rate is retarded by 100 times with the inclusion of trans isoprene unit. This, difference in behaviour is discussed in terms of the possibility of including non-crystallizable units in the crystal lattice. The growth rate analysis showed the importance of determining the equilibrium melting temperature and glass transition temperature for each isomerized specimen to obtain meaningful estimates of

Developing of targeted drug delivery systems is currently a very important topic, which can be easily judged by a great number of papers published every year. Materials science proposes, among others, microcapsules as one of the possible solutions to the problem. Known for more than a decade by know, microcapsules, their properties, methods of encapsulation, release, control where under thorough investigation by several scientific groups in the world. Despite the fact that many factors were already studied, application of this system to drug delivery provides an enormous amount of work yet to be done, lying across several areas of science – biology, chemistry, physics, medicine. To be used as a technique of targeted delivery, not only the microcapsules should meet many constraints on their physical and chemical properties, but also the means of their control and release triggering irradiation should be applicable and harmless to living body. This means, that there's a lot more to do than to encapsulate the substances of interest and make sure they stay inside the capsules. This is why this research was devoted to investigation of stability of cargo encapsulated to layer-by-layer microcapsules constructed on silica and CaCO3 microparticles using various shell constructions with synthetic and biodegradable polyelectrolytes, nanoparticles, DNA, enzyme and other materials, methods of microcapsules control by magnetic field, which can be used for navigation of the carriers in-vivo to the place of interest and methods of release of encapsulated substances from the microcapsules, that are friendly to living body. The thesis starts with introduction and a literature review to help reader to get a better understanding on the structures discussed in this work and what have already been done in the area. These are followed by a short description of main materials and methods used to conduct this research. Three following chapters of experimental section describe the research itself. Chapter 4 shows feasibility of triggered IR-laser and high-frequency ultrasound release, including intracellular release. Reporting application of cargo using pH-sensitve dye is shown. Ultrasoundtriggered release at parameters, close to that currently used in medical applications, is shown to achieve up to 60% efficiency of previously reported highpower 20 kHz ultrasonic irradiation. Feasibility of laser-induced triggered release using microcapsules functionalized photo-sensitive dyes was also shown. In Chapter 5 retention of activity of DNA and enzyme molecules upon encapsulation was demonstrated. Activity of encapsulated substances was shown to be lower, than of free ones, but the accessibility and kinetics of reactions can be controlled by adjusting the construction of microcapsules. In Chapter 6 feasibility of control of cells impregnated with microcapsules functionalized with magnetite nanoparticles was shown at distances of up to 10 mm using usual constant magnets.

The reduction of wear debris and metal ions from metal-on-metal (MoM) cobalt chromium molybdenum (CoCrMo) hip replacements is needed to help reduce the incidence of adverse tissue responses that cause the high clinical failure rate of these previously popular devices. In addition, infection following primary and revision hip joint replacement surgery is a major complication and has a serious impact on a patient's quality of life whilst putting an economic strain on the health care system; silver (Ag) has been used successfully in medicine as an antibacterial. A range of surface engineered CoCrMo surfaces were investigated for wear and ion release using up to 4 million cycles (Mc) of hip simulator wear testing. Wear testing was performed using both standard acetabular orientation (35°) and more clinically adverse orientation (60°). Bearings were further challenged halfway through a wear test by subjecting the bearings to repeated head and cup luxation-reposition cycles (partial dislocation followed by reduction), and then the effects on subsequent wear and ion release investigated. Electron beam physical vapour deposition (EBPVD) was used to deposit chromium nitride (CrN) and Ag-doped CrN (CrN-Ag; 17, 41 and 51 wt.% Ag) coatings onto large diameter CoCrMo heads and cups. A number of CoCrMo hips were triode plasma nitrided (TPN) or treated using a duplex process of TPN followed by CrN coating. A total of 27 hip bearings were tested, which included current, clinically available MoM controls. All coatings acted as a barrier to Co dissolution using a static immersion model. CrN coating reduced wear rates by 58% - 100% compared to conventional MoM hips. Most notably there was a 99% reduction in Co release into the simulator lubricant when tested at both cups inclinations following 2.00 Mc, and a reduction of 89% when tested following a severe coating damage protocol. The MoM bearings showed signs of the selfpolishing phenomenon often associated with these types of bearings. Wear of the CrN-Ag bearings was similarly lower than the MoM controls in all wear phases, and the CrN-Ag coatings reduced Co release. Approximately 70% of the total Ag released over duration of the test was released over the first 0.17 Mc cycles of wear testing and was predominantly contained within wear particles rather than as ionic Ag. Adverse head and iii cup damage resulted in catastrophic failure of the 17 wt.% Ag coating, but the 51 wt.% Ag coating was the lowest wearing, indicating that the self-lubricating properties of Ag played a role in the tribological contact. The TPN bearings wore almost twice as much as the MoM controls and released twice the amount of Co; the duplex bearings wore almost 5-times more than the CrN coating and did not act as a barrier to Co release. The poor wear and ion release characteristics of the bearings that had been nitrided was attributed to nitrogen (N) having a stronger affinity for Cr than Co. Although the results of the present thesis indicate that both wear and ion release can be reduced by utilising EBPVD CrN-based surface coatings, it is likely that, given the current observations of high rates of failure of MoM implants, that surface engineering of MoM will not be embraced in the near future. However, there may be opportunities to exploit this technology in alternative orthopaedic implant applications.

Bone is a complex fibrous biological nanocomposite material optimized to avoid catastrophic failure and to perform a variety of mechanical functions, most notably load bearing. The fracture behaviour of bone is expected to be controlled by the various structural features present across the many existing hierarchical length scales. Micron sized bone lamellae present the simplest composite unit in bone consisting of mineralized collagen fibrils within a protein matrix, with some work suggesting that this length scale dominates the fracture of whole bone. However, the synergy between the bone components even at these relatively small length scales is poorly understood. The aim of this work is to therefore examine the mechanical properties of bone at length scales where the bone material itself can be considered as a composite material. To achieve this, discrete volumes of bone corresponding to the sub-lamellar unit were mechanically tested using an in situ Atomic Force Microscope (AFM) while monitoring using Scanning Electron Microscope (SEM). The elastic modulus of sub-lamellar bone units mechanically tested by the AFM in a bending configuration within the SEM was shown to be similar in both wet and SEM vacuum conditions, indicating that the SEM vacuum is insufficiently strong to drive off water from hydrated bone samples at lamellae length scales. AFM-SEM mechanical testing was extended to determine the structural effects of collagen fibril orientation in bone sub-lamellar units on both elastic modulus and fracture. Final experiments examined small scale mechanical properties of osteoporotic Mechanical Properties of Bone at the Sub-lamellar Level Queen Mary University of London 3 bone, with results highlighting how osteoporosis has little effect on the strength of the bone material but lowers the elastic modulus. This work therefore highlights the use of small scale mechanical testing using AFM and SEM to determine the influence of structural organization, specifically collagen fibril orientation, and compositional changes induced by osteoporosis on resultant bone material behaviour.

Fibrous materials are used in a variety of applications due to their relatively high surface area to volume ratio as well as anisotropic behaviour. Electrospinning is a popular fabrication technique which produces polymer nanofibres with a potentially high molecular orientation. The surface of polymer fibres plays a significant role in many applications thus measurement of their surface properties is essential but challenging due to their relatively small size. In this thesis, ultrafine nanofibres have been produced by electrospinning with their nanofibre morphology controlled by varying different processing parameters. Atomic force microscopy (AFM) adhesion contact mechanics and individual nanofibre wetting measurements have been conducted to explore surface properties of the produced electrospun polymer fibres. Results using traditional Owens-Wendt plots applied to our nanomaterials show electrospun nanofibres have a higher dispersive surface free energy compared to bulk polymer film but a lower polar contribution, giving a total surface free energy in excess of bulk equivalents. A novel proposed model indicates that this nanofibre dispersive surface free energy is intimately linked to density of the polymer and ultimately the molecular spacing or orientation for the polymer chains. Comparisons are made with bulk polymer films to show that a high degree of molecular orientation is present at least at the surface of the polymer nanofibre. Structure investigations on electrospun fibres of polyvinyl alcohol using FTIR and XPS surface techniques explore how an increase in hydrogen bonds formed within nanofibres rather than on the fibre surface enhance this dispersive contribution but lowers the polar contribution. The wetting behaviour of electrospun fibre is extended to assemblies at length scales above individual fibres to highlight how superhydrophobic surfaces can be produced from nanofibre networks with defined spacings and geometries. This superhydrophobicity was adequately described by a Cassie-Baxter model modified to account for the fibrous geometry.

Polymeric coating research requires advanced spectroscopic techniques to perform more efficient and detailed analysis in order to improve knowledge on the component distribution and the degradation of functional groups in the coating. In this work, the advanced non-destructive Step-scan Photoacoustic (SSPA) FTIR and Confocal Raman Microscopy (CRM) techniques were developed and applied to the component distribution studies and degradation studies of polyester/melamine based coil coating. The results show that both techniques are very suitable to carry out both qualitative and quantitative analyses. The degradation of polyester/melamine coil coating exposed in various environmental conditions were studied in detail using the advanced SSPA-FTIR and CRM techniques; the results clearly show that the coating degradation is highly dependent on the weathering conditions. Acid rain was also found to significantly affect the coating durability. Moreover, different pigments incorporated into the coating formulation were also found to have a major impact on the coating durability. With the help of the powerful CRM component distribution analysis function, melamine enriched zones that were very likely to arise from the melamine self-condensation during the curing process of coil coating were clearly observed in the coatings. This finding confirms the hypothesis developed over 20 years in the coil coating research field. Moreover, the durability of the melamine enriched zones was also investigated in this work.

This thesis describes the synthesis, characterization and device properties of a range of conjugated polymers incorporating 3,6-dilakylthieno[3,2-b]thiophene. We report a new and facile synthesis for the preparation of 3,6-dialkylthieno[3,2-b]thiophene, which is readily scaled up to the multi-gram scale. With this synthesis in hand, we initially investigated the properties of poly(thienothiophene-alt-vinylene) polymers incorporating both straight and branched side-chains. Two different polymerization methods were investigated to synthesise the conjugated polymers, namely Stille and Gilch polymerization. The Gilch route was found to lead to high molecular-weight polymers with less cis-defects in the backbone. The polymers were found to be largely amorphous by X-ray diffraction measurements, although there were clear signs of aggregation by optical investigations. Field-effect transistors fabricated with these polymers exhibited charge carrier mobilities up to 0.02 cm2 V-1 s-1 for the straight chain analogue, with the branched polymer displaying lower mobilities. Blends with PC71BM were found to exhibit solar cell device efficiencies up to 2.5 %, with significant differences observed for polymers containing two different side-chains. In the third chapter we investigated the properties of ethynylene-linked 3,6-dialkylthieno[3,2-b]thiophene polymers. The simple homo-polymers were found to exhibit much worse device performance than the analogous vinylene-containing polymers in transistor devices. Co-polymers with a range of electron accepting monomers were also synthesized. These displayed low optical energy gaps and signs of aggregation in the solid state. Transistors were fabricated and their performance examined. In the final part of this thesis, co-polymers bearing 3,6-dialkylthieno[3,2-b]thiophene donor and squaraine acceptor units were synthesized. These zwitterionic conjugated polymers displayed band gaps as low as 1.0 eV. The influence of the nature of the side-chains and co-monomer was investigated with regard to their optoelectronic properties.