Micelle Formation and Hydrophobic Bonding in Deuterium Oxide^1,2

Abstract

The critical micelle concentrations of sodium decyl and lauryl sulfates at 25 deg have been determined from precise conductance data in water and in heavy water. The critical concentrations in heavy water are slightly lower. The solubility of sodium lauryl sulfate at 9 deg C is also only about 5% lower in heavy water. The conductance of both small ions and micelles approximately follow Walden's rule. The interpretation of the solubility and the critical concentration data lead to somewhat conflicting estimates regarding the relative strength of hydrophobic bonding in the two media: the difference in either case appears to be small. it is suggested that this result may be misleading because of compensating effects of dimerization of the long-chain ions. (auth)