  Normal micelle aggregates of amphiphilic surfactant in aqueous solvent are
formed by a process of entropically driven self-assembly. The self-assembly of
reverse micelles from amphiphilic surfactant in non-polar solvent in the
presence of water is considered to be an enthalpically driven process. While
the formation of normal and reverse surfactant micelles has been well
characterized in theory and experiment, the nature of dry micelle formation,
from amphiphilic surfactant in non-polar solvent in the absence of water, is
poorly understood. In this study, a theory of dry reverse micelle formation is
developed. Variation in free energy during micelle assembly is derived for the
specific case of AOT surfactant in isooctane solvent using atomistic molecular
dynamics simulation analyzed using the energy representation method. The
existence and thermodynamic stability of dry reverse micelles of limited size
are confirmed. The abrupt occurence of monodisperse aggregates is a clear
signature a critical micelle concentration, commonly observed in the formation
of normal surfactant micelles. The morphology of large dry micelles provides
insight into the nature of the thermodynamic driving forces stabilizing the
formation of the surfactant aggregates. Overall, this study provides detailed
insight into the structure and stability of dry reverse micelles assembly in
non-polar solvent.
