标题：Molecular Dynamics Study of Alkyl Benzene Sulfonate at Air/Water Interface: Effect pf Inorganic Salts
作者：Taotao Zhao;Guijing Xu;Shiling Yuan
作者机构：[Zhao, T] Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan 250100, China;[ Xu, G] Key Laboratory o 更多
通讯作者地址：[Xu, GY]Shandong Univ, Minist Educ, Key Lab Colloid & Interface Chem, Jinan 250100, Peoples R China.
来源：The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical
摘要：Molecular dynamics simulations have been performed to investigate the effect of inorganic salts On the structural and dynamic properties of alkyl benzene sulfonate monolayer formed at the air/water interface. The alkyl benzene sulfonates are two surfactant isomers in the family of sodium hexadecane benzene sulfonates defined by 1C16 and 5C16, indicating a benzene sulfonate group attached to the first and fifth carbon atom in hexadecane backbone. It has been observed that both benzene ring groups and headgroups (-SO_3~-) are hydrated due to their polar nature. Water molecules can form stable hydrogen bonds with headgroups of surfactants, and the counterions (Na~+, Mg~(2+), or Ca~(2+)) are distributed close to the air/ water interface. The stronger electrostatic repulsion drives the 1C16 monolayer arranged in disorder in comparison with SC16, and the presence of inorganic salts may screen electrostatic repulsions between headgroups and decrease the thickness of the interfacial water layer, which follows the series: Ca~(2+) > Mg~(2+) > Na~+. The order of inorganic salt tolerance of two surfactants is 5C16 > 1C16. The: counterions may penetrate into the hydration shell of the surfactant headgroups and restrict the mobility of the water molecules situated in this area.