Growth and hydration of Triton X-100 micelles in monovalent alkali salts:: A light scattering study

The purpose of this paper is to investigate the effect of various alkali-metal chloride electrolytes on the micellar formation process of Triton X-100. We have studied the micellar solutions by using static and dynamic light scattering. A combined analysis of the data obtained from both techniques has been carried out in the context of micellar structure and hydration. To examine the effect of the size and hydration of ions on the micellar growth, experiments with three different electrolytes (LiCl, NaCl, and CsCl) covering a wide range of ionic strength (0-2 M salt added) have been performed. It was found that both the ionic strength and the cation nature have a substantial effect on the micellar growth. The postulated growth mechanism consists of a progressive process involving both an increase in the micellar aggregation number accompanied with a rise of associated water which is nonspecifically bonded with the micelle. However, the amount of water molecules hydrogen bonded was found to decrease with the electrolyte addition. This mechanism is supported by the observed tendencies in both the partial specific volume and the cloud point of the surfactant for each added electrolyte.