engleski

Statistical and thermodynamical analysis of the micro-structure in molecular emulsions

Aqueous mixtures differ from mixtures of simple liquids from the fact that water molecules tend to self-associate preferentially due to the hydrogen bonding interaction, hence segregating solute molecules, without however leading to macroscopic phase separation. Even simple mixtures such as water with methanol exhibit such local order. The resulting micro-heterogeneity (MH) appear then as distinct from concentration fluctuations (CF), which play an important role in the stability of mixtures. By establishing a correspondence between micro-emulsions and these mixtures that we name as “molecular emulsions”, from the small wave number form of the Ornstein-Zernike theory, we demonstrate how certain difficulties intrinsic to molecular simulations can be avoided by accounting for the long-range form of the correlations. Similarly, by introducing bridge functions which we extract from simulation results of neat liquids, a better understanding of the behaviour of liquid state integral equation theories is achieved, which in particular help a better understanding of the difference between CF and MH.

aqueous mixtures; concentration fluctuations; micro-heterogeneity; integral equations; computer simulations; molecular emulsions

Doktorat pod dvojnim mentorstvom (cotutelle)