<p>Optical beams that travel through a material without undergoing divergence are known as self-trapped beams. Self-trapping occurs when a beam induces a suitable index gradient in the medium that is capable of guiding the original beam. An incoherent light consists of femtosecond scale speckles, due to random phase fluctuations and were not thought to self-trap until recently. In 1997, Mitchell et al., showed that white light can self-trap, provided the medium cannot respond fast enough to form index gradients to these speckles individually. However, detailed studies have been hampered by a lack of suitable materials and strategies for enabling such a response. In 2006, our group showed that a photopolymer is suitable for incoherent self-trapping, since the index change is governed by an inherently slow rate of polymerization (of the order of milliseconds). This has enabled further studies of various phenomena with white light self-trapping.</p> <p>The studies here show (i) the first direct experimental evidence of interactions of two incoherent white light self-trapped beams, as well as fission, fusion and repulsion. Existence of dark self-trapping beams with incoherent white light was also shown, counter intuitively in a positive nonlinear medium. (iii) Lattices were formed with multiple ordered bright as well as dark self-trapping filaments using optochemical self-organization. (iv) Woodpile-like 3D lattices with bright and dark beams were also demonstrated and simulations showed theoretical band gaps. (v) Self-trapping of a co-axial beam of incoherent white light was also shown experimentally and through simulations.</p> / Doctor of Philosophy (PhD)

Tailored fluoropolymers remain the leading choice for a wide variety of advanced high-performance applications, including electronic/optical and energy conversion, owing to their unique blend of complementary high-performance properties. Amorphous semi-fluorinated polymers exhibit improved solubility and melt processability when compared to traditional perfluoropolymers. A leading class of semi-fluorinated aryl ether polymers includes perfluorocyclobutyl (PFCB), perfluorocycloalkenyl (PFCA), and fluoroarylene vinylene ether (FAVE) polymers. Monomers containing aromatic trifluorovinyl ethers (TFVE) are used to synthesize PFCB polymers via radical-mediated [2+2] cyclodimerization. On the other hand, FAVE and PFCA polymers are polymerized via base-mediated nucleophilic addition/elimination of bisphenols with TFVE monomers and decafluorocyclohexene respectively. The use of different monomer cores (aromatic, aliphatic, contorted, and renewable) should help to develop general structure/property relationships for this versatile and expanding approach to semi-fluorinated aryl ether polymers. The enchainment of polycyclic aromatic hydrocarbon (PAH) cores with functional fluorocarbon groups (or segments) recently afforded a new class of semi- fluorinated polymers in the continuing quest for novel organic materials for potential applications in optoelectronic, gas-separation, and advanced composites. Chapter 2 details the incorporation of commercially available acenaphthenequinone was achieved to afford PFCB aryl ether polymers with excellent solubility, high thermal stability, and film-forming capability. Chapter 3 represents base-promoted nucleophilic addition/elimination of commercial bisphenols with TFVE-triphenylene monomers affording FAVE aryl ether polymers possessing excellent solution processability, high thermal stability and photostability. In addition, triphenylene-enchained FAVE polymers exhibit extreme thermal-oxidative photostability and emit blue light after heating in air at 250 °C for 24 h. Further, time-dependent density functional theory (TD-DFT) computations were performed to understand electronic polymer structures. In one case, post-polymerization Scholl coupling converted the central triphenylene core to afford a hexabenzocoronene containing semi-fluorinated polymer with new optoelectronic properties. Chapter 4 demonstrates synthesis and characterization of renewable semi-fluorinated polymers obtained using aliphatic diol isosorbide. This renewable diol readily polymerizes with bis-TFVE derivatives of bisphenol A and 6F to provide high molecular weight thermoplastics exhibiting excellent solubility and tough, transparent film-forming capability. Finally, Chapter 5 presents synthesis of TFVE enchained corannulene which gave blue-light emission and outstanding processability. Synthesis and characterization, including the new materials' optical, thermal, and electronic properties, is presented.

Cemented carbide tools are subjected to high loads and temperatures during use. Long before any significant wear can occur on the tool, the material will experience plastic deformation. The purpose of this master thesis was to investigate how Kernel Average Misorientation (KAM) can be utilised to analyse plastic deformation within the microstructure or grains of cemented carbides. Six different cemented carbides were investigated. The materials were plastically deformed by utilizing cutting tests with a feed rate staircase method to induce the plastic deformation. Each material was characterised by using Scanning Electron Microscopy (SEM) either equipped with a secondary electron detector or an Electron Backscatter Diffraction detector (EBSD). This made it possible to investigate the WC grain size, Co infiltration, step formation, cavities and pores, KAM and the average grain size. It was concluded that KAM showed to be a valuable tool to visualise the plastic deformation in the materials. There were some limitations to KAM regarding materials with similar amounts of plastic deformation. Additionally, the data from KAM could be used to create graphs to more easily display the misorientation. However, KAM cannot showcase the mechanisms that lead to plastic deformation. Other characterisation methods are needed as a compliment to completely understand what is happening in the material on a microstructural level.

The work in this thesis mainly focuses on the preparation and characterization of several phosphates and solid oxide systems with the aim of developing new proton conducting materials for intermediate temperature fuel cells (ITFCs). Soft chemical methods such as sol-gel methods and conventional solid state methods were applied for the synthesis of these materials. Aluminum phosphate obtained by a solution method is single phase and belongs to one of the Al(H₂PO₄)₃ allotropies with hexagonal symmetry. The material is stable up to 200°C and decomposes into Al(PO₃)₃ at a higher temperature. The electrical conductivity of pure Al(H₂PO₄)₃ is on the order of 10⁻⁶-10⁻⁷ S/cm, very close to the value for the known proton conductors AlH₃(PO₄)₂•3H₂O and AlH₂P₃O₁₀•2H₂O. Much higher conductivity is observed for samples containing even a trace amount of excess H₃PO₄. It is likely that the conduction path gradually changes from grain interior to the surface as the acid content increases. The conductivity of Al(H₂PO₄)₃-0.5H₃PO₄ exhibited a good stability over the measured 110 hours. Although tin pyrophosphate (SnP₂O₇) has been reported to show a significantly high conductivity (~10⁻² S/cm) at 250°C in various atmospheres, we observed large discrepancies in the electrical properties of SnP₂O₇ prepared by different methods. Using an excess amount of phosphorous in the synthetic procedure generally produces SnP₂O₇ with much higher conductivity (several orders of magnitude higher) than samples with stoichiometric Sn:P ratios in their synthetic procedure. Solid state ³¹P NMR confirmed the presence of residual phosphoric acid for samples with excess starting phosphorous. Transmission Electron Microscope (TEM) confirmed an amorphous layer covered the SnP₂O₇ granules which was probably phosphoric acid or condensed phases. Thereby, it is quite likely that the high conductivity of SnP₂O₇ results mainly from the contribution of the residual acid. The conductivity of these samples exhibited a good stability over the measured 80 hours. Based on the observations for SnP₂O₇, we developed a nano core-shell structure based on BPO₄ and P₂O₅ synthesised by solid state methods. The particle size of BPO₄ using this method varied between 10-20 nm depending on the content of P₂O₅. TEM confirmed the existence of an amorphous layer that is homogeneously distributed. The composite exhibits the highest conductivity of 8.8×10⁻² S/cm at 300°C in air for 20% extra P₂O₅ and demonstrates a good stability during the whole measured 110 hours. Polytetrafluoroethylene (PTFE) was introduced into the composites in order to increase malleability for fabrication. The conductivity and mechanical strength were optimized by adjusting the PTFE and P₂O₅ content. These organic-inorganic composites demonstrate much better stability at elevated temperature (250°C) over conventional SiC-H₃PO₄-PTFE composites which are common electrolytes for phosphoric acid fuel cells (PAFCs). Fuel cells based on BPO₄-H₃PO₄-PTFE composite as the electrolyte were investigated using pure H₂ and methanol as fuels. A maximum power density of 320 mW/cm² at a voltage of 0.31 V and a maximum current density of 1.9 A/cm² at 200°C were observed for H₂/O₂ fuel cells. A maximum power density of 40 mW/cm² and maximum current of 300 mA/cm² 275°C were observed when 3M methanol was used in the cell. Phosphoric acid was also introduced into materials with internal open structures such as phosphotungstic acid (H₃PW₁₂O₄₀) and heteropolyacid salt ((NH₄)₃PW₁₂O₄₀), for the purpose of acquiring additional connections. The hybrids obtained have a cubic symmetry with enlarged unit cell volume, probably due to the incorporation of phosphoric acid into the internal structures. Solid state ³¹P NMR performed on H₃PW₁₂O₄₀-xH₃PO₄ (x = 0-3) showed additional peaks at high acid content which could not assigned to phosphorus from the starting materials, suggesting a strong interaction between H₃PW₁₂O₄₀ and H₃PO₄. The conductivity of hybrids was improved significantly compared with samples without phosphoric acid. Fourier transform infrared spectra (FT-IR) suggest the existence of large amount of hydrogen bonds (OH••••O) that may responsible for the high conductivity. A H₂/O₂ fuel cell based on H₃PW₁₂O₄₀-H₃PO₄-PTFE exhibited a peak power density of 2.7 mW/cm² at 0.3 V in ambient temperature. Solid oxide proton conductors based on yttrium doped BaZrO₃ were investigated by introducing potassium or lanthanum at the A-sites. The materials were prepared by different methods and were obtained as a single phase with space group Pm-3m (221). The unit cell of these samples is slightly smaller than the undoped one. The upper limit of solid solution formation on the A-sites for potassium is between 5 ~ 10% as introducing more K results in the occurrence of a second phase or impurities such as YSZ (yttrium stabilized zirconium). K doped Barium zirconates showed an improved water uptake capability even with 5% K doping, whereas for La doped ones, water uptake is strongly dependent on particle size and synthetic history. The conductivity of K doped BaZrO₃ was improved by a factor of two (2×10⁻³ S/cm) at 600°C compared with undoped material. Fuel cells based on Pt/Ba₀₋₉₅K₀₋₀₅Zr₀₋₈₅Y₀₋₁₁Zn₀₋₀₄O[subscript(3-δ)]/Pt under humidified 5% H₂/air conditions gave a maximum power density 7.7 mWcm⁻² at 718°C and an interfacial resistance 4 Ωcm⁻². While for La doped samples, the conductivity was comparable with undoped ones; the benefits of introducing lanthanum at A-sites may not be so obvious as deficiency of barium is one factor that leads to the diminishing conductivity.

Existing methods for pathogen/pollutant detection or wound infection monitoring employ high-cost instruments that could only be operated by trained personnel, and costly device-based detection requires a time-consuming field-to-lab process. This expensive process with multiple prerequisites prolongs the time that patients must wait for a diagnosis. Therefore, improved methods for point-of-care biosensing are necessary. In this study, we aimed to develop a direct, easy-to-use, portable, low cost, highly sensitive and selective sensor platform with the goal of pollutant detection and wound infection/cancer migration monitoring. This study has two main parts, including microfluidic, electrical, and optical sensing platforms. The first part, including chapters 2, 3, and 4, focuses on Bisphenol A (BPA) lateral flow assay (LFA) detection; the second part, including chapter 5 focuses on the electrical sensing platform fabrication for one of the markers of inflammation, matrix metalloproteinases-9 (MMP-9), monitoring/detection. In chapters 2, 3, and 4, we found that the few lateral flow assays (LFAs) established for detecting the endocrine-disrupting chemical BPA have employed citrate-stabilized gold nanoparticles (GNPs), which have inevitable limitations and instability issues. To address these limitations, in chapter 2, a more stable and more sensitive biosensor is developed by designing strategies for modifying the surfaces of GNPs with polyethylene glycol and then testing their effectiveness and sensitivity toward BPA in an LFA. In chapter 3, we describe the development of a new range-extended bisphenol A (BPA) detection method that uses a surface enhanced Raman scattering lateral flow assay (SERS-LFA) binary system. In chapter 4, we examine advanced bisphenol A (BPA) lateral flow assays (LFAs) that use multiple nanosystems. The assays include three nanosystems, namely, gold nanostars, gold nanocubes, and gold nanorods, which are rarely applied in LFAs, compared with general gold nanoparticles. The developed LFAs show different performances in the detection of BPA. In chapter 5, a stable electrical sensing platform is developed for MMP-9 detection.

The relatively new and still growing field of 3D-printing has opened up the possibilities to manufacture patient-specific medical devices with high geometrical accuracy in a precise and quick manner. Additionally, biocompatible materials are a demand for all medical applications while biodegradability is of importance when developing scaffolds for tissue growth for instance. With respect to this, this project consisted of developing biocompatible and bioresorbable polymer blend and composite filaments, for fused deposition modeling (FDM) printing. Poly(lactic acid) (PLA) and polycaprolactone (PCL) were used as supporting polymer matrix while hydroxyapatite (HA), a calcium phosphate with similar chemical composition to the mineral phase of human bone, was added to the composites to enhance the biological activity. PLA and PCL content was varied between 90–70 wt% and 10-30 wt%, respectively, while the HA content was 15 wt% in all composites. All materials were characterized in terms of mechanical properties, thermal stability, chemical composition and morphology. An accelerated degradation study of the materials was also executed in order to investigate the degradation behavior as well as the impact of the degradation on the above mentioned properties. The results showed that all processed materials exhibited higher mechanical properties compared to the human trabecular bone, even after degradation with a mass loss of around 30% for the polymer blends and 60% for the composites. It was also apparent that the mineral accelerated the polymer degradation significantly, which can be advantageous for injuries with faster healing time, requiring only support for a shorter time period.

Nanomaterials, typically less than 100 nm size in any direction have gained noteworthy interest from scientific community owing to their significantly different and often improved physical properties compared to their bulk counterparts. Semiconductor nanoparticles (NPs) are of great interest to study their tunable optical properties, primarily as a function of size and shape. Accordingly, there has been a lot of attention paid to synthesize discrete semiconducting nanoparticles, of where Group III-V and II-VI materials have been studied extensively. In contrast, Group IV and Group IV-V based nanocrystals as earth abundant and less-non-toxic semiconductors have not been studied thoroughly. From the class of Group IV, Ge1-xSnx alloys are prime candidates for the fabrication of Si-compatible applications in the field of electronic and photonic devices, transistors, and charge storage devices. In addition, Ge1-xSnx alloys are potentials candidates for bio-sensing applications as alternative to toxic materials. Tin phosphides, a class of Group IV-V materials with their promising applications in thermoelectric, photocatalytic, and charge storage devices. However, both aforementioned semiconductors have not been studied thoroughly for their full potential in visible (Vis) to near infrared (NIR) optoelectronic applications. In this dissertation research, we have successfully developed unique synthetic strategies to produce Ge1-xSnx alloy quantum dots (QDs) and tin phosphide (Sn3P4, SnP, and Sn4P3) nanoparticles with tunable physical properties and crystal structures for potential applications in IR technologies. Low-cost, less-non-toxic, and abundantly-produced Ge1-xSnx alloys are an interesting class of narrow energy-gap semiconductors that received noteworthy interest in optical technologies. Admixing of α-Sn into Ge results in an indirect-to-direct bandgap crossover significantly improving light absorption and emission relative to indirect-gap Ge. However, the narrow energy-gaps reported for bulk Ge1-xSnx alloys have become a major impediment for their widespread application in optoelectronics. Herein, we report the first colloidal synthesis of Ge1-xSnx alloy quantum dots (QDs) with narrow size dispersity (3.3±0.5 – 5.9±0.8 nm), wide range of Sn compositions (0–20.6%), and composition-tunable energy-gaps and near infrared (IR) photoluminescence (PL). The structural analysis of alloy QDs indicates linear expansion of cubic Ge lattice with increasing Sn, suggesting the formation of strain-free nanoalloys. The successful incorporation of α-Sn into crystalline Ge has been confirmed by electron microscopy, which suggests the homogeneous solid solution behavior of QDs. The quantum confinement effects have resulted in energy gaps that are significantly blue-shifted from bulk Ge for Ge1-xSnx alloy QDs with composition-tunable absorption onsets (1.72–0.84 eV for x=1.5–20.6%) and PL peaks (1.62–1.31 eV for x=1.5–5.6%). Time-resolved PL (TRPL) spectroscopy revealed microsecond and nanosecond timescale decays at 15 K and 295 K, respectively owing to radiative recombination of dark and bright excitons as well as the interplay of surface traps and core electronic states. Realization of low-to-non-toxic and silicon-compatible Ge1-xSnx QDs with composition-tunable near IR PL allows the unprecedented expansion of direct-gap Group IV semiconductors to a wide range of biomedical and advanced technological studies. Tin phosphides are a class of materials that received noteworthy interest in photocatalysis, charge storage and thermoelectric devices. Dual stable oxidation states of tin (Sn2+ and Sn4+) enable tin phosphides to exhibit different stoichiometries and crystal phases. However, the synthesis of such nanostructures with control over morphology and crystal structure has proven a challenging task. Herein, we report the first colloidal synthesis of size, shape, and phase controlled, narrowly disperse rhombohedral Sn4P3, hexagonal SnP, and amorphous tin phosphide nanoparticles (NPs) displaying tunable morphologies and size dependent physical properties. The control over NP morphology and crystal phase was achieved by tuning the nucleation/growth temperature, molar ratio of Sn/P, and incorporation of additional coordinating solvents (alkylphosphines). The absorption spectra of smaller NPs exhibit size-dependent blue shifts in energy gaps (0.88–1.38 eV) compared to the theoretical value of bulk Sn3P4 (0.83 eV), consistent with quantum confinement effects. The amorphous NPs adopt rhombohedral Sn4P3 and hexagonal SnP crystal structures at 180 and 250 °C, respectively. Structural and surface analysis indicates consistent bond energies for phosphorus across different crystal phases, whereas the rhombohedral Sn4P3 NPs demonstrate Sn oxidation states distinctive from those of the hexagonal and amorphous NPs owing to complex chemical structure. All phases exhibit N(1s) and ʋ(N-H) energies suggestive of alkylamine surface functionalization and are devoid of tetragonal Sn impurities.

The transition from fossil fuels to renewable resources has created more demand for energy storage devices. Lithium-oxygen (Li-O2) batteries have attracted much attention due to their high theoretical energy densities. They, however, are still in their infancy and several fundamental challenges remain to be addressed. Advanced analytical techniques have revealed that all components of a Li-O2 battery undergo undesirable degradation during discharge/charge cycling, contributing to reduced cyclability. Despite many attempts to minimize the anode and cathode degradation, the electrolyte remains as the leading cause for rapid capacity fading and poor cyclability in Li-O2 batteries. In this dissertation, composite gel polymer electrolytes (cGPEs) consisting of a UV-curable polymer, tetragylme based electrolyte, and glass microfibers with a diameter of ~1 µm and an aspect ratio of >100 have been developed for their use in Li-O2 battery application. The Li-O2 batteries containing cGPEs showed superior charge/discharge cycling for 500 mAh.g-1 cycle capacity with as high as 400% increase in cycles for cGPE over gel polymer electrolytes (GPEs). Results using in-situ electrochemical impedance spectroscopy (EIS), Raman spectroscopy, and scanning electron microscopy revealed that the source of the improvement was the reduction of the rate of lithium carbonates formation on the surface of the cathode. This decrease in formation rate afforded by cGPE-containing batteries was possible due to the decrease of the rate of electrolyte decomposition. The increase in solvated to the paired Li+ ratio at the cathode, afforded by increased lithium transference number, helped lessen the probability of superoxide radicals reacting with the tetraglyme solvent. This stabilization during cycling helped prolong the cycling life of the batteries. The effect of ion complexes on the stability of liquid glyme based electrolytes with various lithium salt concentrations has also been investigated for Li-O2 batteries. Charge/discharge cycling with a cycle capacity of 500 mAh·g-1 showed an improvement as high as 300% for electrolytes containing higher lithium salt concentrations. Analysis of the Raman spectroscopy data of the electrolytes suggested that the increase in lithium salt concentration afforded the formation of cation-solvent complexes, which in turn, mitigated the tetragylme degradation.

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.