The interplay of hydrophilic and hydrophobic interactions are vital in biological systems, including protein structure and macromolecular self-assembly.  However, despite many years of study, even phenomena of simple amphiphilic molecules such as alcohols in water have only been vaguely interpreted at a molecular level. Here, the interactions between water and the hydroxyl head and hydrocarbon tail of alcohols are studied in molecular dynamics simulations of alcohol-water mixtures. A comparison is presented of methanol, ethanol, propanol, and butanol aqueous mixtures, focusing on the intermolecular behavior that leads to anomalous behavior such as the concentration dependence of the partial molar volumes and the formation of an azeotrope. In particular, the preferential hydration of the hydroxyl head group plays a key role at all concentrations while the hydrophobic association is predominately important only in dilute concentrations of alcohols.

Hydrophilic and hydrophobic interactions in alcohol-water mixtures

244th National Meeting (2012)

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