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This thesis reports the synthesis of complex architectures via group transfer polymerisation (GTP), specifically well-defined multiblock and gradient copolymers. As a living polymerisation method, GTP has been demonstrated at industrial scale for block copolymer synthesis by sequential addition of monomers. The aim of this thesis was to demonstrate that GTP can be used to fabricate copolymers with complex architectures. The first study is on multiblock copolymers, which are block copolymers with more than three distinct blocks. Sequential polymerisation was used to demonstrate scalable synthesis of four pentadecablock (15-block) copolymers AB7A bipolymers and (ABCDE)3 quintopolymers) and polymerisation of a heneicosablock (24-block) bipolymer. The following chapters study the synthesis of gradient polymers. Gradient copolymers have a progressive change in monomer composition which may prove beneficial for modifying the properties of thermoresponsive gels. For the first time, gradient copolymers have been produced with a stepwise (or many-shot) polymerisation protocol with GTP. A-gradient-B and A-gradient-B-gradient-A copolymers were prepared with GTP. Comparable block and statistical copolymers were also prepared to investigate structure-property relationships. Polymer series were synthesised with thermoresponsive monomers 2-(dimethylamino)ethyl methacrylate (DMAEMA) and di(ethylene glycol) methyl ether methacrylate (DEGMA). The cloud point temperatures were lower than the comparable di/triblock copolymer, and micelle diameters were determined to be larger due to the diffuse core-corona transition. \par The polymerisation control provided by GTP resulted in low dispersity values (Đ < 1.3) for all copolymers in this thesis, despite the complex architectures produced. The Mn closely matched the Mth and polymer composition was confirmed by NMR. Due to high conversion rates and fast polymerisation rates, all polymers were prepared in less than 6 hours per polymerisation. The number of commercially available methacrylate monomers and the tolerance for many functional groups indicate that GTP can readily prepare copolymers with complex architectures suitable for many applications.

The study of magnetohydrodynamics unifies the fields of fluid mechanics and electrodynamics to describe the interactions between magnetic fields and electrically conducting fluids. Flows described by magnetohydrodynamics form a significant aspect in a wide range of engineering applications, from the liquid metal blankets designed to surround and remove heat from nuclear fusion reactors, to the delivery and guidance of nanoparticles in magnetic targeted drug delivery. The ability to optimize these, and other, processes is increasingly reliant on the accuracy and stability of the numerical models used to predict such flows. This thesis addresses this by providing a detailed assessment on the performance of two electromagnetically extended Reynolds-averaged Navier-Stokes models through computations of a number of electromagnetically influenced simple channel and Rayleigh-Bènard convective flows. The models tested were the low-Re k-ε linear eddy-viscosity model of Launder and Sharma (1974), with electromagnetic modifications as proposed by Kenjereš and Hanjalić (2000), and the low-Re stress-transport model of Hanjalić and Jakirlić (1993), with electromagnetic modifications as proposed by Kenjereš and Hanjalić (2004). First, a one-dimensional fully-developed turbulent channel flow was considered over a range of Reynolds and Hartmann numbers with a magnetic field applied in both wall-normal and streamwise directions. Results showed that contributions from the electromagnetic modifications were modest and, whilst both models inherently captured some of the reduction in mean strain that a wall-normal field imposed, results from the stress-transport model were consistently superior for both magnetic field directions. Then, three-dimensional time-dependent Rayleigh-Bènard convection was considered for two different Prandtl numbers, two different magnetic field directions and over a range of Hartmann numbers. Results revealed that, at sufficiently high magnetic field strengths, a dramatic reorganization of the flow structure is predicted to occur. The vertical magnetic field led to a larger number of thinner, more cylindrical plumes whilst the horizontal magnetic field caused a striking realignment of the roll cells' axes with the magnetic field lines. This was in agreement with both existing numerical simulations and physical intuition. The superior performance of the modified stress-transport model in both flows was attributed to both its ability to provide better representation of stress generation and other processes, and its ability to accommodate the electromagnetic modifications in a more natural, and exact, fashion. The results demonstrate the capabilities of the stress-transport approach in modelling MHD flows that are relevant to industry and offer potential for those wishing to control flow structure or levels of turbulence without recourse to mechanical means.