Solvophobic interactions and micelle formation in structure forming nonaqueous solvents.

Abstract

HYDROPHOBIC interactions are important in maintaining the conformations of proteins and various macromolecules. The free energies of these interactions are entropic in origin, for the enthalpy changes are actually unfavourable at low temperatures (ΔH>0). It is generally believed that around the nonpolar parts of the solutes in contact with water there is an increased ordering1–3 of the water molecules as a result of hydrogen bonding, and that on the formation of the hydrophobic bond this order is diminished so that there is a positive entropy change. We have recently shown4 that there are solvophobic interactions in ethylene glycol, a polar nonaqueous solvent, chiefly on the grounds of the formation of micelles by several cationic detergents and the limited solubility of hydrocarbons in this solvent.