Micelles of SDS Surfactants in Concentrated NaCl Solutions

We investigated the aggregation behavior of rod‐like micelles of sodium dodecyl sulfate (SDS) in concentrated NaCl solution by quasi‐elastic light scattering (QLS) and viscosity measurement over a range of temperature (25 °C to 50 °C) and NaCl concentration. The reduced viscosity of aqueous SDS in the presence of NaCl has been measured by an Ubbelohde‐type capillary viscometer. We show mean hydrodynamic radius of micelles can be determined from viscosity data. We also determined mean hydrodynamic radius using quasi‐elastic light scattering. Micellar size decreases with increasing temperature, whereas it increases with increasing ionic strength. The results of viscosity and dynamic light‐scattering measurements are interpreted as the extension of length of rod‐like micelles. We compare viscosity and light scattering experimental results.