"Statistical-mechanical theories will be developed and computer simulations carried out on model colloidal systems of semi-flexible rods and discs. The phase behaviour, structural and dynamical properties will be investigated as a function of the degree of internal particle flexibility. A more general virial theory for the isotropic-to-nematic phase transition in worm-like rods, which includes the third virial term in the excess free energy expression, will be formulated and worked out. This theory will be extended to inhomogeneous phases, such as smectic and columnar. The investigation of worm-like rod systems will serve as the basis for subsequent work on flexible, sheet-like particles, which constitutes the central research objective of the fellowship. The virial theory will be extended and applied to systems of flexible discs. For these, few results are available at present and it is not even known whether some degree of flexibility of the platelets will suppress the isotropic-nematic transition or not. The project seeks to settle this matter. The effect of the third virial term on the isotropic-to-nematic phase transition will be investigated. The stability of more ordered phases, such as the columnar phase, upon introducing and increasing internal particle flexibility, will be addressed. Concomitantly, for both rod-like and disc-like particle systems, computer simulations will be carried out and the results for phase behaviour compared with the theoretical predictions. Simulation will give also access to structural and dynamical properties of the phases involved. The topics addressed are of general importance in Soft Matter and the models considered mimic a wealth of experimental systems, such as rod-like virus particles, rod-like and disc-like clay particles, and bio-membranes, which are of current technological and biological importance."