Adsorption of mixed DDA/NaOL surfactants at the air/water interface by molecular dynamics simulations. (22nd November 2016)

• Record Type: Journal Article
• Authors: Wang, Li; Liu, Runqing; Hu, Yuehua; Sun, Wei
• Is Part Of: Chemical engineering science. Volume 155(2016)
• Page Start: 167
• Page End: 174
• Publication Date: 2016-11-22
• Subjects: Mixed DDA/NaOL surfactants -- Molecular dynamics simulation -- Adsorption -- Aggregation; Chemical engineering -- Periodicals; Génie chimique -- Périodiques; Chemical engineering; Periodicals; Electronic journals; 660
• DOI: 10.1016/j.ces.2016.08.012
• Languages: English
• ISSNs: 0009-2509

Abstract

Abstract: The adsorption behavior of mixed cationic dodecylamine (DDA)/anionic sodium oleate (NaOL) at different molar ratios at the air/water interface were investigated using molecular dynamics (MD) simulations. Some parameters such as the distribution of headgroups, carbon chains, counterions and water, as well as the headgroups-water radial distribution function, were calculated. The simulation results show that compared to pure DDA and NaOL, their mixtures are more compact and can form a tight monolayer at the air/water interface, indicating higher surface activity. The polar groups of surfactants are tilted into the liquid phase because of strong interactions with water; meanwhile, the hydrophobic carbon chains stretch towards the air phase at a smaller angle than pure surfactant. Water molecules can gather easily and aggregate around the headgroups in the mixed surfactants system. The order of the surface activity is as follows: DDA/NaOL=1/3>DDA/NaOL=1/1> DDA/NaOL=3/1. These results demonstrate a strong synergistic interaction between DDA and NaOL at the air/water interface. Graphical abstract: Highlights: Surface properties of mixed DDA/NaOL surfactants are presented. Strong synergistic interactions observe between DDA and NaOL. Mixed DDA/NaOL form compactness monolayer at the air/water interface. Mixed DDA/NaOL show higher activity than their component.