# A fluid bilayer phase in aqueous mixtures of fatty alcohol and cationic surfactant

## TL;DR

This study uses atomistic molecular dynamics simulations to demonstrate the existence of a fluid bilayer phase in aqueous mixtures of fatty alcohols and cationic surfactants, revealing complex temperature-dependent behavior.

## Contribution

First simulation-based evidence of a fluid bilayer phase in fatty alcohol and surfactant mixtures, enhancing understanding of their self-assembly and phase behavior.

## Key findings

- Identification of a fluid bilayer in simulations
- Rich temperature phase diagram matching experimental features
- Unambiguous signature of fluid bilayer behavior

## Abstract

The $L_\alpha$ phase of lipid bilayers is a fluid self-assembled state, key to the formulation of cosmetics, detergents and pharmaceutics. Despite having been extensively scrutinized in self-assembled phospholipid or surfactant bilayers, the formation of a fluid $L_\alpha$ state has defied understanding in mixtures of fatty alcohols, surfactants and water, where is viewed as the essential step for the preparation of creamy dispersions. Here, atomistic molecular dynamics simulations show the existence of a fluid bilayer in aqueous mixtures of cetyl (C$_{16}$OH) and stearyl (C$_{18}$OH) alcohols, and cetyl-trimethylammonium chloride (CTAC). These simulated bilayer systems display not only a rich temperature phase diagram with many of the features seen in experiments but carry also the unambigous signature of fluid bilayer behavior.