Modeling the aggregation behavior of amphiphiles in the continuous phase of highly concentrated emulsions

Abstract

We investigate the self-assembly of a diblock surfactant in the continuous phase of highly concentrated emulsions. The droplets of the dispersed phase confine the growth of the aggregates, deeply modify their orientation and hence alter their spatial arrangement as compared to the self-assembly taking place far enough from any boundary surface, namely in the bulk. By performing computer simulations, we show that the interface between the dispersed and continuous phases as well as its shape has a significant impact on the structural order of the resulting aggregates and hence on the potential applications of highly concentrated emulsions as reaction media, drug delivery systems, or templates for meso/macroporous materials. Due to the combined effect of symmetry breaking and morphological frustration, very intriguing structures, such as square columnar liquid crystals, twisted X-shaped aggregates, and helical phases of cylindrical aggregates, never observed in the bulk for the same model surfactant, have been found. The presence of other more conventional structures, such as micelles and cubic and hexagonal liquid crystals, formed at low and high amphiphilic concentrations, respectively, further enhance the interest on this already rich aggregation behavior.