Insights into interfacial behaviours of surfactant and polymer: A molecular dynamics simulation

Surfactants and polymers are two common chemicals used to stabilize the wet foam, but molecular-level insights into the structures, dynamics and hydrogen bonds of these agents and water at the surface are still lack. Herein a series of all-atom molecular dynamics simulations were conducted to explore the behaviors of surfactants/polymers at liquid films. Simulations confirmed that OPC water model can better reproduce the surface tension, and surface tension decreases while interface thickness increases as the increase of surfactant surface concentration. Our findings provide molecular insights on the morphology transitions of surfactant monolayers, which is dependent on the van der Waals energy among surfactants. Surfactant monolayers greatly retard the mobility of the interfacial water molecules, but such capability only exists nearby interfacial area. By adding polymers inside, water dynamics can be retarded further through the hydrogen bonding effects. In other words, polymers in the bulk solution produce a “bolt-like” effect which constrains the water around the chains.