Statistical and Molecular Perspectives on Foam Stability: structure-property relationships of trimethyl ammonium bromide at interfaces

Foams stabilized by surfactants play a pivotal role in industry, daily life, and fundamental research.However, the molecular mechanisms governing foam stability, particularly the interplay of surfactant structure and interfacial behavior, remain incompletely understood. Using molecular dynamics combined with advanced statistical analyses, we systematically explored the effects of alkyl trimethyl ammonium bromide (C n TAB) surfactants on foam film stability across varying chain lengths and coverages. Our approach incorporated parallel simulations to ensure robust evaluation of fluctuating properties and employed methods such as sigmoid fitting and kernel density estimation to extract detailed insights into interfacial characteristics. The results reveal that increasing surfactant coverage significantly reduces interfacial tension via enhanced molecular packing, while chain length primarily influences structural properties such as Gibbs Dividing Surface (GDS) thickness and molecular orientation. Longer chains, particularly at high coverage, promote denser packing and resist penetration into the aqueous phase due to steric hindrance and hydrophobic interactions. These findings provide a molecular-level understanding of surfactantstabilized interfaces and establish a robust framework for analyzing interfacial systems, offering insights for optimizing foam formulations in industrial applications.