Microdynamics of threadlike micellar systems

Abstract

This chapter discusses Microdynamic behavior of threadlike micelles is examine by using a fluorescence probing method. Some cationic surfactants form enormously long threadlike micelles in aqueous solution with additives. The long threadlike micelles make concentrated entanglement networks and show pronounced viscoelastic behavior as polymer molecules do in semi-dilute to concentrated conditions. In the concentrated polymer system, the slowest relaxation mode shows a box type relaxation spectrum which means the broad distribution of relaxation modes. In the case of the polymer chain molecule, chain units are tightly bound each other by the covalent chemical bonding. On the other hand, the threadlike micelles are formed with not so strong intermolecular interaction between surfactant molecules called the hydrophobic interaction.This chapter proposes a mode called a phantom crossing model to understand the unique viscoelasticity of the threadlike micellar system. In the model, it is assumed that every entanglement point has a lifetime equal to the mechanical relaxation time, and two threadlike micelles cross each other at an entanglement point when the lifetime is over. In the threadlike micelle, surfactants and additives should have rapid molecular motions. They always alter their positions and rotate quickly to reduce the memory of position and orientation in the micelle, since the micelle forming origin is the intermolecular interaction not the chemical bonding.