Molecular dynamics simulation of sodium dodecylsulfate (SDS) bilayers
Hongshu Zhang1, Shiling Yuan1, Jichao Sun1
1Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100, PR China.
Journal of Colloid and Interface Science
|July 24, 2017
Summary
Sodium dodecylsulfate (SDS) forms stable vesicles from micellar solutions on surfaces. Molecular dynamics reveal SDS bilayers maintain structure over micelles when alkyl chain interdigitation exceeds 8%, driven by salt bridges and bilayer asymmetry.
Area of Science:
- Physical Chemistry
- Materials Science
- Surface Science
Background:
- Single-tailed surfactants like sodium dodecylsulfate (SDS) can self-assemble into stable vesicles.
- Vesicle formation is often mediated by solid surfaces, but the molecular mechanisms are not fully understood.
Purpose of the Study:
- To investigate the molecular-level mechanisms of sodium dodecylsulfate (SDS) vesicle formation and stability.
- To elucidate the role of alkyl chain interdigitation, salt bridges, and bilayer asymmetry in surfactant self-assembly.
Main Methods:
- Molecular dynamics simulations were employed to study SDS bilayer segments detaching from solid surfaces.
- Simulations analyzed the structural transitions of SDS aggregates (bilayers, micelles) based on interdigitation and cross-sectional area.
Main Results:
- SDS bilayers maintain their structure over micelles when the initial alkyl chain interdigitation degree exceeds 8.0±1.4%.
- Equilibrium interdigitation degree stabilizes at 31.7±2.0%.
- SDS aggregates exhibit diverse structures including curved, planar, and perforated bilayers, and micelles, influenced by leaflet area.
- Salt bridges (Na+-DS-) and water bridges contribute to bilayer stability, while leaflet asymmetry aids curvature formation.
Conclusions:
- The study provides molecular insights into SDS vesicle formation and stability, highlighting the importance of interdigitation, salt bridges, and asymmetry.
- Findings contribute to understanding interface phenomena and the self-assembly mechanisms of simple single-tailed surfactants.
