A. G. Vanakaras and D. J. Photinos, J. of Mater. Chem., 11(11), 2832-2838 (2001).
Abstract: A molecular description of the mesomorphic behaviour of globular supermolecules of radial dendritic architecture is presented. It is based on coarse grained structural and conformational features, namely, anisometry of the overall shape, submolecular partitioning of the interactions and non-convexity of the supermolecular surface. The relevance of these features to conformational phase transitions, orientational ordering, layering and microsegregation phenomena in ordered fluid phases is studied using density functional theory of deformable bodies and Monte Carlo simulations of rigid fan molecules. Orientationally ordered and layered phases are found, both in theory and simulation, even in the absence of significant overall shape anisometry.
A. G. Vanakaras, A. F. Terzis and D. J. Photinos, Molec.Cryst. Liq. Cryst., 362, 67-78 (2001).
Abstract: A nematic consisting of rod-like and plate-like molecular species is expected to exhibit phase biaxiality over a range of concentrations. Phase separation, however, prevents the achievement of such concentrations in mixtures of conventional, low molar mass, thermotropic calamitic and discotic mesogens. We present a theoretical study of the molecular requirements for phase biaxiality in three types of rod-plate nematics, namely in (i) binary mixtures of hard rods and discs, (ii) mixtures of rods and discs exhibiting molecular association, either by direct rod-disc interaction or through selective interactions with a third molecular species and (iii) single component systems with interconverting rod-like and plate-like conformations.
A. G. Vanakaras and D.J. Photinos,
Chem. Phys. Lett.,
341(1-2), 129-134 (2001).
Abstract: We have used Monte Carlo (MC) NPT computer simulations to study a system of spherical-fan-shaped particles made of three hard discs fused along a common diameter. The calculated equation of state indicates a strong, entropy driven. first-order transition from the isotropic phase to a layered phase that has the basic characteristics of the usual smectic-A mesophase but with strongly correlated rotations about the symmetry axes of neighbouring molecules.
