Nanoscale physics

Structural features of aqueous solutions of alcohols 
N. Atamas1, 2, G. Taranyik 3
1 Taras Shevchenko National University of Kyiv, Kyiv 01601, Ukraine
E-mail: atamasphys@mail.univ.kiev.ua
2 Institute of Physical Chemistry Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
3 International European University, Kyiv 03187, Ukraine

At a recent time, there has been more and more attention to the study of the mechanisms that regulate hydrophobic and hydrophilic interactions in water, which determine the main causes of the behavior of aqueous solutions of biological macromolecules. Monohydric alcohols, which have both hydrophilic (hydroxyl OH groups), and hydrophobic groups (methyl and ethyl groups) allow to be considered as simple model systems to obtain information on the behavior of biomolecules in water. In addition to the above, in the course of studies of the concentration-structural features of aqueous solutions of monohydric alcohols with the use of Monte Carlo method, the following goals have been being achieved: to study the effect of the hydrophilic properties of alcohols on changes in the structural characteristics of aqueous solutions at various concentrations of alcohol; to build up the model representations for the structure of aqueous solutions of alcohols at various concentrations. On the basis of the studies carried out the following have been established: (1)   in an aqueous solution of ethyl and propyl alcohols at Xal  (< 0.05 ppm of the ethyl alcohol, and 0.04 ppm of propyl alcohol), the alcohol molecule does not change the percolation properties of the network of HB between water molecules;(2) the value of the dipole moment of an alcohol affects the structural characteristics of clusters of alcohol molecules in water at Xal  (0.2-0.25) ppm.;(3)· at Xal > 0.3 ppm. it occurs the structure of clusters is rearranged from alcohol molecules into structures similar to reverse micelles. The number of alcohol molecules that form reverse micelles does not depend on the structure, and dipole moment of alcohol molecules, and is equal to 4 ;(4)· at Xal  (0.6 - 0.8) ppm rupture of micelles formed by alcohol molecules occurs. At these concentrations there can also exist free alcohol molecules, and half-chains of four alcohol molecules as well.