Another Possible Rationale for Foam Stability: The Quantity and Strength of Hydrogen Bonds at the Gas-Liquid Interface.

Abstract

This study examines the foams generated by three surfactants: sodium dodecyl sulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), and sodium lauryl polyoxyethylene ether sulfate (AES). By analyzing the hydrogen bond at the gas-liquid interface, the research provides novel insights into the mechanisms by which surfactants stabilize foams. Surfactants adsorb at the gas-liquid interface, establishing hydrogen bonds with water molecules while simultaneously retarding the structural relaxation of water-water hydrogen bonds within the hydration layer. This phenomenon can impede drainage during the surface tension drainage phase. Surfactants that readily form hydrogen bonds with water are more likely to adsorb at the gas-liquid interface, thereby enhancing the foam stability. The presence of robust hydrogen bonds and the frequent reconstruction of these bonds contribute to the establishment of a stable hydrogen bond network, which can reinforce the gas-liquid film and potentially augment its elasticity, enabling it to better withstand external perturbations. Although the Marangoni effect typically promotes bubble coalescence, a stable hydrogen bond network may mitigate this process.