Kinetics of slow relaxation upon the competition between globular and small spherocylindrical micelles

Abstract

Kinetic description of the slow establishment of complete equilibrium in surfactant solutions with concentrations exceeding the first critical micellization concentration is constructed for the case when surfactant monomers, premicellar spherical aggregates, and globular and small spherocylindrical micelles coexist. The model proposed suggests the presence of two separate branches with minima for the aggregation work of aggregates with aggregation numbers above the limiting spherical packing of surfactant molecules. One of these branches corresponds to globular micelles, while the other corresponds to small spherocylindrical micelles. Transitions between aggregates at each of the branches are taken into account with the absence of direct transitions between aggregates on different branches. Relations obtained reflect correlations between the current values of the concentrations of surfactant monomers and total concentrations of globular and small spherocylindrical micelles and determine the characteristic time of slow relaxation.