Water confined in self-assembled ionic surfactants nano-structures

TL;DR

This study uses computer simulations to explore how water content influences the morphology and interfacial properties of ionic surfactant nano-structures, revealing phase transitions and structural details relevant to soft material interfaces.

Contribution

Introduces a coarse-grained model and simulation analysis of water-surfactant systems, detailing phase behavior and interfacial structures across hydration levels.

Findings

Identification of lamellar, cylindrical, and micellar phases with increasing hydration

Analysis of nano-scale water domain size variations across phases

Insights into water molecule behavior at soft material interfaces

Abstract

We present a coarse-grained model for ionic surfactants in explicit aqueous solutions, and study by computer simulation both the impact of water content on the morphology of the system, and the consequent effect of the formed interfaces on the structural features of the adsorbed fluid. On increasing the hydration level at ambient conditions, the model exhibits a series of three distinct phases: lamellar, cylindrical and micellar. We characterize the different structures in terms of diffraction patterns and neutron scattering static structure factors. We demonstrate that the rate of variation of the nano-metric sizes of the self-assembled water domains shows peculiar changes in the different phases. We also analyse in depth the structure of the water/confining matrix interfaces, the implications of their tunable degree of curvature, and the properties of water molecules in the different restricted environments. Finally, we discuss our results compared to experimental data and their impact on a wide range of important scientific and technological domains, where the behavior of water at the interface with soft materials is crucial.