Butenko O. Supramolecular structure of epitropic liquid crystal layers of nemesogens

The dissertation work presents the results of an experimental (by 3 independent methods) and theoretical study of the physical properties of epitropic liquid crystal (ELC) layers of such compounds as – the homologous series of n-alkanes, monounsaturated fatty oleic acid and nitrobenzene, as aromatic hydrocarbon, formed near metallic, metallized and dielectric substrates. Particular attention in this work was paid to the study of the temperature dependence of the structural properties of ELC layers, to reveal the role of the size (length) of anisometric liquid molecules in the organization of such layers and their properties. Optical and viscometric methods for studying of liquids containing such heterophase layers have been modified. In the “static” triad of friction, two optical methods were used to establish the heterophase state of the liquid layers bounded by the solid substrates, the presence of ELC layers with a supramolecular structure (homeotropic molecular orientation). It has been quantitatively established how the degree of orientational ordering and the equilibrium thickness of such layers decrease with increasing temperature. These results are confirmed by the viscometric study of such layers in the "dynamic" friction triad. The developed rheological models make it possible to reflect the main features of the shear flow of liquid heterophase layers and to determine the structurally sensitive properties of ELC layers. Within the framework of presented models, an assessment was made of the structural parameters formed near the ELC substrates of the layers in liquids under study. The existing molecular - statistical model of the organization of the ELC layer has been developed, within the framework of which it is possible to describe the experimental temperature dependences of the thickness of such a layer, which makes it possible to predict the properties of a large homologous series of liquids under study. The obtained results of the study of orientationally ordered layers are of leading importance in the processes of energy dissipation mechanisms, in the process of their operation in the boundary friction mode, which are relevant for increasing of the wear resistance of the latter.