ETHYLENE OXIDE GROUP EXPANSION AND CO-SURFACTANT EFFECTS ON WORMLIKE MICELLE SYSTEMS : IMPACT ON RHEOLOGICAL BEHAVIOR AND MICELLAR MORPHOLOGY

Surfactants are amphiphilic molecules widely used in industrial and commercial products, especially in the Home & Personal Care sector. Once a certain concentration, known as the critical micelle concentration (CMC), is reached, these molecules aggregate into different shapes, depending on the medium they are in. One of these shapes, known as giant or worm-like micelles, can reach sizes on the micrometric scale.

In this work, we replicated a ternary aqueous system composed of a zwitterionic surfactant, an ethoxylated anionic surfactant, and an anionic co-surfactant. We evaluated the impact of varying the number of ethylene oxide groups present in the anionic surfactant, the presence of the co-surfactant, and the pH of the solutions. The variation of these parameters led to significant changes in the rheological behavior, which did not follow a well-defined linear trend. Additionally, the surfactants formed giant micelles (birefringence under shear flow) of different sizes, verified by cryo-TEM and zero-shear viscosity.