Up to present date, no obvious and reasonable theoretical approach interpreting the formation of worm- or thread-like micelles together with the accompanying sharp change in the rheological properties. Consequently, systems of binary and ternary mixtures of 3 wt% anionic, cationic and nonionic surfactants have been investigated at different temperatures. The mixture of anionic [sodium dodecylsulfate (SDS)] and cationic [cetyltrimethylammonium bromide (CTAB)] surfactants exhibits a remarkable high viscosity peak at weight ratio of 80/20 CTAB/SDS. No wormlike micelles have been detected for binary mixtures of anionic- nonionic (Triton-X 100) nor for ternary mixtures of SDS/CTAB/Triton-X 100 surfactants. Approximate relations have been introduced for evaluating the thermodynamic change from spherical to one-dimensional supramolecular aggregate. Conductivity measurements have been performed for supporting the present investigation. The results reveal a new physical insight called Critical Intermolecular Forces (CIF), which is responsible for the transition phenomenon from three to one-dimensional shape of aggregate. It has been concluded that the suggested theory of CIF plays as a powerful tool in understanding not only the transition state towards wormlike micelles together with the associated significant increasing in solution viscosity, but also for helping researchers who are interested in exploring any kind of new wormlike systems.

Rabah Ali Khalil and Fahad Jumaah Hammad