Sphere-to-Rod Transition of Micelles q R. Nagarajan, Khalid M. Shah and Susan Hammond. Viscometric Detection of Sphere to Cylinder Transition and Polydispersity in Aqueous Micellar Solutions. Colloids and Surfaces, 4, 147-162 (1982). q R. Nagarajan. Are Large Micelles Rigid or Flexible? A Reinterpretation of Viscosity Data for Micellar Solutions. J. Colloid Interface Sci., 90, 477-486 (1982). q R. Nagarajan and E. Ruckenstein. Theory of Surfactant Self-Assembly: A Predictive Molecular Thermodynamic Approach. Langmuir 7, 2934-2969 (1991). q R. Nagarajan. Modeling Solution Entropy in the Theory of Micellization. Colloids and Surfaces A: Physicochem. Eng. Aspects, 71, 39-64 (1993).
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Sphere-to-Rod Transition Parameter K The parameter K determines the average aggregation number of the highly polydispersed spherocylindrical micelles. K stands for the energy penalty incurred by the gcap molecules that are at the two spherical endcaps compared to the molecules located on the cylindrical middle. Knowing K, the average aggregation number can be calculated at any total surfactant concentration X.
The dependence of the sphere-to-rod transition parameter K on the surfactant tail length and on the concentration of added electrolyte NaCl for sodium alkyl sulfates. The lines are predictions obtained from the present theory while the points denote the experimental data based on light scattering from the literature, both at 30^oC. The predicted lines are labeled with the surfactant tail lengths and the corresponding experimental data are indicated by squares, circles, triangles and hexagons, respectively.