Structure formation in binary mixtures of surfactants: vesicle opening-up to bicelles and octopus-like micelles

TL;DR

This study uses coarse-grained molecular simulations to explore how binary surfactant mixtures form various micelle structures, including vesicles, bicelles, and octopus-like micelles, depending on surfactant ratios and concentrations.

Contribution

It reveals new insights into the formation of diverse micelle structures and their connection mechanisms in binary surfactant mixtures, supported by simulation and experimental correlation.

Findings

Formation of bicelles from ruptured vesicles.

Observation of octopus-shaped micelles matching cryo-TEM images.

Identification of two connection structures between worm-like micelles and bicelles.

Abstract

Micelle formation in binary mixtures of surfactants is studied using a coarse-grained molecular simulation. When a vesicle composed of lipid and detergent types of molecules is ruptured, a disk-shaped micelle, the bicelle, is typically formed. It is found that cup-shaped vesicles and bicelles connected with worm-like micelles are also formed depending on the surfactant ratio and critical micelle concentration. The obtained octopus shape of micelles agree with those observed in the cryo-TEM images reported in [S. Jain and F. S. Bates, Macromol. 37, 1511 (2004).]. Two types of connection structures between the worm-like micelles and the bicelles are revealed.