The hydration of hydrophobic substances

A model of the hydration of hydrophobic substances in water is suggested. The models of fluctuation formation of empty cavities in water as a stage of hydration extensively used in the literature were shown to be at variance with experiment. The fundamental role played by the interphase boundary surface was emphasized. On this surface, the successive addition of water molecules with the formation of capsules around hydrophobic molecules occurred. The physical meaning of the Ostwald equation was revealed. This equation characterized the distribution of hydrophobic volatile substances between the gas and aqueous phases. The method of optical probes ( hydrophobic aromatic molecules) was used to reveal the synergistic character of autocorrelation of dispersion interactions between water and hydrophobic substance molecules. This synergism was at variance with the Lennard-Jones potential. The synergism ( superadditivity) of dispersion attraction forces, which strengthened their directional character, caused the self-organization and enhanced stability of hydration capsules with encapsulated hydrophobic molecules. Computer models were used to show that the spatially directional character of dispersion interactions necessary for the self-organization of hydrated aggregates could be simulated by the molecular mechanics method on the basis of orientational correlation of water molecules and hydrophobic substances in the starting system.