Styranets M. Dielectric properties of aqueous solutions of alcohols near their peculiar points.

The work is devoted to a comprehensive study of the optical, dielectric and conductometric parameters of aqueous solutions of alcohols, first of all, the first members of the homologous series of monohydric alcohols– methanol, ethanol and propanol. In previous works, for such systems, a concentration region was identified where the contraction of the solution (the appearance of anegative excess volume during the formation of a solution) does not depend on temperature over the entire range of existence of the liquid system. It was shown that the appearance of a micro-inhomogeneous structure in the vicinity of this singular point leads to anomalies in most physical characteristics, starting with anomalous light scattering. In this work, a deviation from the reference approximation curves of the shear viscosity coefficient of the aqueous solution of ethanol was experimentally obtained, and its position coincided with the anomalies of the light scattering. The obtained temperature dependences of the deviations allowed explaining them by the peculiarities of intermolecular interaction, first of all, by hydrogen bonds. Experimental data on a deviation of the refractive indices of aqueous solutions of monohydric alcohols from smooth curves in the vicinity of the singular point of the contraction were obtained. This deviation consists of two peaks, which are symmetrically located near the peculiar point, and exactly coincides with the previously obtained fine structure of the anomalous light scattering peak in water-ethanol solutions. In this work, the temperature and time dependences of the refractive index were obtained. The found deviation was explained in terms of the method of many-particle polarizabilities in solutions. Experimental dependences of a dielectric constant and conductivity of water-isopropanol solutions were obtained. A long-term (from a day to a week) equilibration in solutions as well as the formation of dependences of electrical parameters in the form of two peaks, which coincide with the dependences of the refractive index, were shown. The performed experiments with a model colloidal system (a nanofluid based on isopropanol) within the framework of the method of compact groups of particles allowed proving the formation of a micro-inhomogeneous structure with the appearance of double electric layers at the boundaries of inhomogeneities in the vicinity of a singular point of water-alcohol solutions.