Effect of water-soluble and water-insoluble long-chain polar additives on micellar solutions of sodium dodecylbenzene sulfonate

Additions of long-chain polar compounds to aqueous solutions of sodium dodecylbenzene sulfonate resulted in the separation of a liquid-crystalline phase. This was first observed after the addition of 0.2 to 0.25 mole of water-insoluble polar compound per mole of anionic surfactant. It was found necessary to add 0.6 to 2 moles of watersoluble long-chain polar compound per mole of anionic surfactant before a separate liquid-crystalline phase could be observed. At concentrations below that required for liquid-crystal formation, additions of PEG 400 monostearate to aqueous solutions of sodium dodecylbenzene sulfonate resulted in a steady decrease in the Krafft temperature, a viscosity minimum, and a surface-tension minimum. With sucrose monotallowate, similar results were obtained, except that a minimum was not obtained in the viscosity-concentration curve.