Micellization of a Cationic Surfactant in Mixed Aqueous and Non-aqueous Solvent Systems

The Micellisation behaviour of sodium dodecyl sulfate (SDS) in different mole fractions (0.1 0.5 and 0.9) of propylene glycol (PG) – water mixed solvents was investigated using electrical conductivity measurement at temperatures of 30, 35 and 40 °C. The critical micelle concentration (CMC) increased and the degree of counterion dissociation values (α) decreased with increase in the composition of PG. Variation of CMC with temperature is marked with U-shaped curves while the degree of counterion dissociation is linear with temperature. These results have been discussed based on the influence of PG on the cohesive forces of the mixed solvents as well as temperature effect on the thermal motion of mixed solvent molecules