The synthesis of 2,4,6,8-Tetramethylcyclotetrasiloxane (D4H), and Poly(methylhydrosiloxane) (PMHS) average molecular weight 1700-3200 g/mol, were functionalized with different repeat units of methoxy polyethylene glycol (PEG) (n = 8,12,17). These compounds act as polymer electrolytes with a backbone of siloxane and they were prepared via hydro-silylation reaction to be functionalized with different molecular weights of Ally-PEG. The compounds were confirmed by FT-IR, 1H-NMR and 13C NMR spectroscopy. A hydro-silylation reaction between the functionalized AllyPEG of different molecular weights produced four compounds with a low glass transition temperature that could improve comb like polymer electrolytes conductivity by reducing crystalline phase of PEO. Another way to increase the percentage of the amorphous phase of PEO is to blend it with other polymers. The blending method is considered to be an important method to improve the ionic conductivities and dimensional stability of polymer electrolytes. The main advantages of the blend systems are the simplicity of preparation and the ease to control the physical properties. A high molecular weight of poly 2- vinyl pyridine (Mw=200,000) was added to improve the dimensional stability. Differential scanning calorimetry (DSC) thermal analysis shows that all the blend systems will exhibit an increase in the glass transition temperature by increasing the salt content. The other novel synthesis of polymer electrolytes are triglyme borane and borosilicate. They were synthesized via hydro-boration. These compounds were characterized and confirmed by FT-IR, 1H-NMR 13C NMR spectroscopy. The ionic conductivity of both systems, pure and blend, of different compositions were determined at four temperatures i.e. 25°C, 40°C, 55°C and 70°C. A maximum ionic conductivity value of the siloxane blend is 9.1x10-4 S cm-1 and the pure triglyme borane is 2.14x10-3 S cm-1 at ambient temperature. The ratios of ethylene oxide to lithium salt of siloxane blend and pure triglyme borane were 10:1 and 35:1 respectively. These ratios were the highest conductivity obtained in all the electrolyte systems. The ionic conductivity increases with increasing temperature and salt content to reach optimum concentration. This behavior results in ionic transport, which is supported by the segmental motion of the polymer matrix host.

The spinel structure (general formula AB2O4) is widely occurring in natural and synthetic materials, and has a marked technological and scientific significance due to its magnetic, electric and multiferroic behaviours. The presence of transition metal cations with multiple oxidation state and the resulting charge, orbital and spin degrees of freedom of the partially occupied d-orbitals lead to uniquely ordered ground states. The coupling of all the three degrees of freedom can result in a structurally distorted ground state where the direct metal-metal interaction forms atomic clusters, or 'orbital molecules'. The Verwey phase of magnetite (Fe3O4), occurring below TV ~ 125 K, is driven by a cooperative bond distortion that forms linear Fe3+-Fe2+-Fe3+ arrangement (trimeron). The effect of non-stoichiometry and chemical modification on this complex structure has been investigated with a variety of samples through microcrystal synchrotron XRD. A mineral sample (Al, Si, Mg and Mn impurities, TV = 119 K) confirms the Verwey phase as the most complex long-range electronic order known to occur naturally; its relevance in space sciences is discussed. Moreover, the structural analysis of two synthetic magnetites (Fe3(1-δ)O4 with 3δ = 0.012 and TV = 102 K, Fe3-xZnxO4 with x = 0.03 and TV = 90 K) univocally confirmed the persistence of the transition, and its first order, at doping level > 1 %, contrary to previous reports. Moreover, the temperature evolution of the trimerons and their persistence above TV was probed through X-ray Pair Distribution Function analysis on pure Fe3O4: the data analysis between 90 K < T < 923 K show that the Verwey phase goes from long-range ordered (T < 125 K) to short-range ordered (T > 850 K). Magnetite can thus only be considered to have a regular cubic spinel structure above the Curie temperature (TC = 858 K). The pyrochlore lattice of B cations in a spinel gives the structure the potential for frustration upon antiferromagnetic ordering. Fe2GeO4 and γ-Fe2SiO4 were synthesised through conventional solid state routes, with the use of high-pressure synthesis for the latter. Magnetometry and heat capacity measurements highlighted two transitions (Tm1 = 8.6 K and Tm2 = 7.2 K, and Tm1 = 11.2 K and Tm2 = 7.5 K respectively). Powder neutron diffraction data between 2 K < T < 25 K showed that both materials stay undistorted below TN. Magnetic Rietveld refinement led to two highly unconventional magnetic structures, with incommensurate propagation vectors and modulation of the moment magnitude. γ-Fe2SiO4 also shows a spin-ice order below Tm2. The results are unique and unusual for transition metal oxides; the models are systematised by proposing a 'frustration wave' model, in which the degree of frustration is a spatial quantity that can be distributed through the structure in order to stabilise the ground state.

Silica gels containing incorporated heteropolyacids (HPAs) were synthesized in acidic media by co-condensation of tetraethoxysilane (TEOS) with phosphotungstic or phosphomolybdic acids using sol-gel technique. Effect of the synthesis conditions on their structure and morphology was studied. Yields of modified materials were some lower as compared to non-modified silica gels. All materials were mesoporous but contained micropores in their structures. Presence of bands of Keggin’s structures in FT-IR spectra along with absence of XRD patterns of crystalline HPAs confirmed their fine incorporation into silica network. Particle sizes of modified materials were 800-1100 nm excepting for W-containing sample obtained with trimethylstearylammonium chloride. This unusual effect was attributed to stabilization of primary silica nanoparticles by interaction between surfactant and HPA. High ratio HPA/TEOS resulted in partial loss of porosity. Obtained results might be used for optimization of synthesis of effective catalysts and adsorbents containing HPAs in mesoporous structure.

Mesoporous silica gel containing embedded phosphotungstic acid (PTA) was synthesized by sol-gel co-condensation of tetraethyl orthosilicate with PTA in acidic media. The obtained material had high Brunauer-Emmett-Teller Theory (BET) surface area and pore volume. A characteristic band of the Keggin structure of PTA was present in its FT-IR spectrum while its X-ray diffraction patterns were absent. This proved the embedding of PTA on a sub-molecular level and not as a second phase. Acidic sites were determined by neutralization with base in aprotic solvent, followed by titration of the remaining base with an acid. The material demonstrated high adsorption capacity of Cs. Kinetic studies showed that the adsorption data correlates strongly with the pseudo-second order model. At higher temperatures, the nature of adsorption fit the Langmuir model extremely well. The obtained results can be used in the development of an effective adsorbent for clean-up of water contaminated by radioactive 137Cs.

1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM]Tf2N) was investigated as a multifunctional solvent, ligand, and reducing agent for platinum deposition onto well-defined CdSe@CdS nanorods. Platinum deposition was carried out thermally and photochemically using Pt(acac)2 as the metal precursor. Thermal deposition was investigated in [BMIM]Tf2N with and without addition of a sacrificial reducing agent, and product topology was compared with the products obtained from polyol reduction using 1,2-hexadecanediol, oleic acid, and oleylamine in diphenyl ether. Photochemically induced platinum deposition was carried out at room temperature in [BMIM]Tf2N, and product topology was compared with the photodeposition products obtained from a toluene dispersion. Thermal deposition of platinum in ionic liquid showed rods of broken morphology and small platinum nanoparticles speckled across the rods’ surface, while photodeposition of platinum exhibited particles decorated throughout the nanorod surface but larger in size than those exhibited by thermal means. Photocatalytic reduction of methylene blue was studied using these Pt-CdSe@CdS heterostructured nanoparticles, and catalytic performance was correlated with topology and synthetic history. Initial findings of catalytic performance suggest that there in an advantage of depositing platinum nanoparticles onto the CdSe@CdS in the ionic liquid system. Methylene blue dye was degraded using each system and the results show and there is an increased performance of the nanorods synthesized in the ionic system.

Growing resistance of bacteria towards antibiotics resulted in extensive research effort for development and application of new materials and techniques. Due to their unique properties, graphene quantum dots (GQDs) have attracted much attention and are a promising material with potential applications in many fields. One use of GQDs is as a photodynamic therapy agent that generates singlet oxygen. In this work, GQDs synthesized by focusing nanosecond laser pulses into a mixture of benzene and nickel(II) oxide were combined with methylene blue (MB) to eradicate Gram-negative Escherichia coli and Gram-positive Micrococcus luteus. Theoretical calculation of pressure evolution was calculated using the standard finite difference method. Detailed characterizations were performed with transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), UV-Visible (UV-Vis), and photoluminescence (PL) spectra. Furthermore, singlet oxygen generation from MB-GQD mixture was investigated by measuring the rate of 9,10-anthracenediyl-bis(methylene) dimalonic acid photobleaching at 400 nm. Combining MB with GQDs caused enhanced singlet oxygen generation, leading to improved bacterial deactivation rate. The (3-(4,5-dimethylthiazol-2- yl)-2,5-diphenyltetrazolium bromide) (MTT) assay was used to determine if GQDs in dark conditions caused human cellular side-effects and affected cancer and noncancer cellular viability. We found that even high concentrations of GQDs do not alter viability under dark conditions. These results suggest that the MB-GQD combination is a promising photodynamic therapy agent that may be useful when antibiotics resistance is present.

Lignin, the second most abundant biopolymer on earth, is potentially a replaceable source for bulky fuels and chemical feedstocks. There have been numerous reports on methods for the oxidative cleavage of β-O-4 linkages but relatively few reports of how those methods affect other linkages that are present in lignin. We investigated how the β-1 and β-5 linkages respond under oxidative conditions proposed for lignin deconstruction based on their effect on β-O-4 linkages. Mechanochemical treatment of lignin can greatly improve the yield of monomer products and we applied a mechanochemical approach, using powerful ring-and-puck milling to promote lignin degradation. Along with similar production of monomers in a much shorter period than what we observed in previous ball-milling process, much more unexpected reactions were taking place during the current mechanochemical process. Lignin is a promising feedstock for epoxy resins since lignin-derived aromatic monomers usually bear hydroxyl and carboxyl groups. We are working on utilizing these mono-aromatic compounds and highly-functionalized-lignin as precursors for preparation of epoxy thermosets. We are interested in investigating the properties of thermosets by utilizing the actual isolated monomer streams from raw lignin. We expect to observe attractive thermal and mechanical properties from these lignin-derived epoxy thermosets compare to that of the commercialized but currently limited-used BPA-based epoxy resins.

Encapsulation of nanoparticles within hexaniobate nanoscrolls presents interesting advances in the formation of nanocomposites exhibiting unique multi-dimensional properties. Building upon previous successes, facile yet versatile wet-chemical and microwave-irradiation synthetic protocols for the fabrication of a series of hexaniobate composites are presented herein. Solvothermal and, more recently, microwave-assisted methods have been developed that allow for the fabrication of peapod-like structures. During solvothermal treatment, exfoliated hexaniobate nanosheets scroll around highly ordered chains of preformed nanoparticles (NPs) to produce nanopeapods (NPPs). This approach offers versatility and high yields, in addition to the potential for advanced functional device fabrication. For the characterization of these materials, advanced techniques in atomic force microscopy (AFM) were used for investigating the surface of materials at the nanometer scale. Extensive physical, dynamic, and force modulation studies were performed on novel oxide nanocomposites by implementing particular scanning techniques to determine information such as topology, stress-induced behavior at the nanoscale, magnetic behavior, and frictional forces of the nanoscale materials. These composites were then analyzed by topological intermittent contact studies in tapping and contact mode, as well as with derivative techniques of these commonly used scanning probe approaches. In addition to studying surfaces using conventional modes of AFM, the mechanical properties of these nanocomposites were measured via dynamic lateral force modulation (DLFM) and magnetic properties of functionalized magnetic nanosheets were mapped via magnetic sampling modulation (MSM). By utilizing the capabilities of the DLFM imaging mode, elastic properties such as Young’s Modulus were measured from force-distance curves. In addition to this modulation mode, MSM was used to selectively map the vibrating magnetic nanomaterials from a modulated electromagnetic field. The information obtained from these AFM techniques can be helpful in determining the relative structural behavior of these nanocomposites and gauge their use in various applications such as structural engineering of nanoarchitectures as well as studying magnetic characteristics of metal oxide nanocomposites that exhibit characteristics different from their bulk counterparts.

With the rapid progress of nanotechnologies, there are two developing trends for the next generation of sensors: miniaturization and multi-functionality. Device miniaturization requires less power consumption, or even self-powered system. Multi-functional devices are usually based on multi-property coupling effects. Piezoelectric semiconductors have been considered to be potential candidates for self-powered/multi-functional devices due to their piezotronic coupling effect. In this dissertation, ZnO and CdSe nanowire arrays have been synthesized as the piezoelectric semiconductor materials to develop the following self-powered/multi-functional sensors: (1) self-powered gas sensors of ZnO/SnO2, ZnO/In2O3, ZnO/WO3 and CdSe nanowire arrays have been assembled. All these gas sensors are capable of detecting oxidizing gas and reducing gas without any external power supply owing to piezotronic effect which can convert mechanical energies to electrical energy to power the sensors; (2) a self-powered ZnO/ZnSe core/shell nanowire array photodetector has been fabricated. This photodetector is able to detect the entire range of the visible spectrum as well as UV light because of its type II heterostructure. The absolute sensitivity and the percentage change in responsivity of the photodetector were significantly enhanced resulting from the piezo-phototronic effect. The photodetector also exhibited self-powered photodetection behavior; (3) three dimensional nanowire arrays, such as ZnO and ZnO/Co3O4, have been synthesized to investigate piezo-magnetotronic and piezo-photo-magnetotronic effects. Under magnetic field, the magnetic-induced current of ZnO nanowire array decreased as magnetic field increased, and the current difference was magnified by one order of magnitude caused by piezo-magnetotronic effect through applying a stress. In contrast, under UV light illumination, the current response increased with an increment of magnetic field. The current difference was enhanced by at least two orders of magnitude attributed to piezo-photo-magnetotronic effect. Furthermore, ZnO/Co3O4 core/shell structure was employed to further improve the magnetic-induced current difference. This phenomenon projects a potential for multi-functional piezo-magnetotronic and piezo-photo-magnetotronic device development.

Maintaining a constant supply of clean drinking water is among the most pressing global challenges in our time. About one-third of the population is affected by the water scarcity and it can only get worse with climate change, rapid industrialization, and the population growth. Even though nearly 70 percent of the planet is covered by water, the consumable freshwater content is only 2.5 percent of it. Unfortunately, the accessible portion of it is only 1 percent. Even so, most of the freshwater bodies are choked with pollution. Considering the vast availability of saline water on the planet and the increasing wastewater generation, seawater desalination, and wastewater treatment and recycling seem to have the potential to address current water-related issues. Therefore, it is necessary to find efficient techniques for seawater desalination and wastewater treatment. The use of nanostructured materials for these applications is becoming a popular approach due to the unique chemical and physical properties they possess compared to bulk materials Solar energy is the cleanest and most abundant renewable natural resource available. Materials for solar photothermal energy conversion are highly sought after for their cost savings, clean environment, and broad utility in providing water heating and/or steam for many applications including domestic water heating and solar-driven desalination. Extensive research efforts have been made to develop efficient solar absorbers with characteristics such as low weight, low thermal conductivity, broad solar absorption and porosity to be able to float on water to provide more efficient and cost-effective solar steam generation systems. Metal NPs have been proposed to take advantage of the high efficiency of the photothermal energy conversion associated with surface plasmon resonance absorption. Nanostructured carbon-based materials such as graphene oxide, carbon nanotubes, carbonized biomass are also in use due to their excellent photothermal energy conversion ability over the range of the visible and near infra-red region of the electromagnetic spectrum. In this dissertation, five projects based on the utility of nanostructured materials for desalination, photocatalysis and water treatment will be discussed. The first three projects involve the fabrication and design of plasmonic and carbon-based photothermal materials for applications in solar steam generation, water desalination, and wastewater treatment. In the fourth project, a unique shape of ZnO nanostructure was synthesized for photodegradation of organic dyes in industrial wastewater. The final project demonstrates the shape-controlled synthesis of iron carbide nanostructures and composite materials of aminated graphene oxide for the removal of Cr(VI) from wastewater.