Aggregation number and critical micellar concentration of surfactant determined by time-dependent static light scattering (TDSLS) and conductivity

The use of an automatic continuous mixing (ACM) technique which includes time-dependent static light scattering (TDSLS), refractometric and conductimetric detectors allowed detailed measurements of colloid solutions to be made while varying ionic strength. A ionic surfactant, sodium dodecylsulfate (SDS), was used in NaCl solutions. The critical micellar concentration, CMC, the ionization degree α, the aggregation number and the second virial coefficient were determined. The method has several advantages over traditional manual methods in terms of accuracy, sample preparation, and being less tedious.