This dissertation is focused on thermal transport at nanometer scale point and line constrictions and in nanowires with sawtooth surface roughness. To better understand thermal transport at a point contact such as that at the tip-sample junction of a scanning probe microscope, a Non Equilibrium Molecular Dynamics (NEMD) method is employed to calculate the temperature distribution and thermal resistance of a nanoscale point constriction formed between two silicon substrates. The simulation reveals surface reconstruction at the two free silicon surfaces and at the constriction. The radius of the heated zone in the cold substrate approaches a limit of about 20 times the average nearest-neighbor distance of boron doping atoms when the constriction radius (a) is reduced below the inter-dopant distance. The phonon mean free path at the constriction is suppressed by diffuse phonon-surface scattering and phonon-impurity scattering. The MD thermal resistance is close to the ballistic resistance when a is larger than 1 nm, suggesting that surface reconstruction does not reduce the phonon transmission coefficient significantly. When a is 0.5 nm and comparable to the dominant phonon wavelength, however, the NEMD result is considerably lower than the calculated ballistic resistance because bulk phonon dispersion and bulk potential are not longer accurate. The MD thermal resistance of the constriction increases slightly with increasing doping concentration due to the increase in the diffusive resistance. The NEMD method is further employed to calculate the temperature distribution and thermal resistance at nanoscale line constrictions formed between two silicone substrates. Similar to the nano point constriction, the thermal resistance at the nano line constriction is dominated by the ballistic resistance for constriction width in the range of 1 nm to 12 nm. An additional question that this dissertation seeks to answer is whether one can engineer the surface roughness on a nanowire to facilitate phonon backscattering so as to reduce the thermal conductivity below the diffuse surface limit. Monte Carlo simulation is used to show that phonon backscattering can occur at sawtooth surfaces of a silicon nanowire, suppressing the thermal conductivity below the diffuse surface limit. Asymmetric sawtooth nanowire surfaces can further cause phonon rectification, making the axial thermal conductance of the nanowire direction dependent. The phonon backscattering and rectification effects can be employed to enhance the thermoelectric figure of merit of nanowires. / text

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M. Tech. Chemical Engineering. / Discusses the scope of this research study composes of three interactive steps. The first step involves the design of the specific zeolite system (ZSM-5) and the set-up of an autoclave reactor for the hydrothermal synthesis of this and other zeolites and nano materials, then the oxidation catalyst (TS-1) development, i.e. the substitution of aluminium with titanium in the zeolite framework, and finally the formulation and preparation of the isomorphous Silicalite zeolite by omitting the aluminium in the synthesis. And further, set-up of suitable equipments and apparatus for the catalytic testing of the Titanium Silicalite-1 in the oxidation reaction of phenol as the test reaction. Therefore, the overall objectives of this research are: set up an autoclave reactor for the hydrothermal synthesis, formulation of a synthesis recipe for MFI family of catalysts in the laboratory, synthesis of ZSM-5, Silicalite-1, and TS-1 zeolites catalysts in the laboratory, characterization and optimization of the of catalysts listed above, testing the Ti-Silicalite catalyst in the oxidation reaction of phenol with hydrogen peroxide, as the oxidant, set up analytical system (Gas Chromatography, ASS) for analysis of catalyst performance in the oxidation reaction, Evaluate the conversion of the reaction and the selectivity of the individual catalysts reaction Evaluate the conversion of the reaction and the selectivity of the individual catalysts reaction and verify results obtained and compare with systems described in the literature.

M. Tech. Department of Chemical, Metallurgical and Materials Engineering. / Aimes to explore the effect of using N-CNTs in comparison with undoped CNTs as an anchor for silver or metallic nanoparticles. The metal/CNT will be polymerized with beta-cyclodextrin and will be used as adsorbent for water purification.

M. Tech. Engineering Chemical. / Developes and evaluate next generation antimicrobial filtration systems based on oligodynamic nanoparticles for complimentary water disinfection systems (CDWS) in under developed regions

M. Tech. Computational and theoretical nanotechnology. / Focusses on the multicomponent/multifunctional nanomaterial. This will increase the complexity of aerosol processes and the demands for their control. Process simulations via energy balance, mass balance and population balance modelling will provide a perspective for parameter studies, process and product optimisation, besides gaining a deeper understanding of the process consideration. However, quality and amount of information of any result obtained from such simulation depends on the assumptions and approximations adopted.

A series of hybrid component based on reactive polyhedral oligomeric silsesquioxane(POSS) precusors and its reactive copolymers of PGMA were synthesized and utilized to nanobuild in epoxy. Reactive POSS and copolymer dispersed in homogenous in matrix, overcomed POSS-POSS interaction, which resulted in macroscale phase separation. The nanocomposites obtained were analyzed by Scanning electron microscopy, Transmission electron microscopy, X-ray scattering and dynamic mechanical. An analogue of POSS (denoted as POSSMOCA) was synthesized via addition reaction, which had reactive amino group bonding into epoxy network and improved the thermostability, because of the structural silicon, nitrogen and halogen. Epoxy/polyhedral oligomeric silsesquioxanes (POSS) hybrid composites were prepared from prereaction between trifunctional silanol POSS-OH and diglycidyl ether of bisphenol A (DGEBA) via silanol and the oxirane group. Reactive POSS-PGMA was polymerized via Reversible addition-fragmentation transfer polymerization. It was easy to tail the compatibility of the epoxide block copolymer with a step-growth polymerized matrix, to form nanostructure via reaction with PGMA segements. In the case of inert POSS-PMMA copolymers modified epoxy, topology of copolymer defined the final morphology and interaction between epoxy and them, because of directional hydrogen bonding and dilution effect. Tg of different epoxide conversion, obeyed of Gordon-Taylor equation and Kwei equation, k which reflected the interaction of modifier and DGEBA/MEDA and epoxy/amine oligomers, was consistent of the rheology and dynamic results.

Two different interfaces were the focus of study: 1) the interface between disordered amorphous carbon and inorganic materials (metal nanostructures and silicon), and 2) the interface between partially ordered graphene (graphene oxide) and synthetic polymer matrix. Specifically, the uniqueness of this study can be summarized through the following novel findings, fabrication processes, and characterization techniques: • A simple and efficient process for faster, greener, less-expensive, and highly localized transformation of amorphous carbon nanostructures into graphitic nanostructures using low temperature heat and light treatments was developed for the fabrication of low-resistance interfaces between carbon nanomaterials and inorganic metal surfaces. • A new protocol for high resolution mapping the charge distribution and electronic properties of nanoscale chemically heterogeneous domains on non-homogeneous surfaces such as graphene oxide was established. • High strength laminated mechanical nanocomposites based on high interfacial stress transfer between polymer matrices and large area, flat, and non-wrinkled graphene oxide sheets were suggested and demonstrated. • Scanning Thermal Twist Microscopy – a thermal microscopy based technique was developed and demonstrated for characterizing the thermal properties of homogeneous and heterogeneous interfaces with nanoscale spatial resolution and high thermal sensitivity unachievable using traditional techniques.

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