Molecules, Vol. 26, Pages 6856: Structure and Undulations of Escin Adsorption Layer at Water Surface Studied by Molecular Dynamics

Molecules, Vol. 26, Pages 6856: Structure and Undulations of Escin Adsorption Layer at Water Surface Studied by Molecular Dynamics Molecules doi: 10.3390/molecules26226856 Authors: Sonya Tsibranska Anela Ivanova Slavka Tcholakova Nikolai Denkov The saponin escin, extracted from horse chestnut seeds, forms adsorption layers with high viscoelasticity and low gas permeability. Upon deformation, escin adsorption layers often feature surface wrinkles with characteristic wavelength. In previous studies, we investigated the origin of this behavior and found that the substantial surface elasticity of escin layers may be related to a specific combination of short-, medium-, and long-range attractive forces, leading to tight molecular packing in the layers. In the current study, we performed atomistic molecular dynamics simulations of 441 escin molecules in a dense adsorption layer with an area per molecule of 0.49 nm2. We found that the surfactant molecules are less submerged in water and adopt a more upright position when compared to the characteristics determined in our previous simulations with much smaller molecular models. The number of neighbouring molecules and their local orientation, however, remain similar in the different-size models. To maintain their preferred mutual orientation, the escin molecules segregate into well-ordered domains and spontaneously form wrinkled layers. The same specific interactions (H-bonds, dipole–dipole attraction, and intermediate...
Source: Molecules - Category: Chemistry Authors: Tags: Article Source Type: research