Adsorption Characteristics of Sodium Dodecyl Sulfate on Zwitterionic Functionalized Alumina: A Molecular Dynamics Study

Abstract

A classical molecular dynamics simulation was conducted in order to determine the extent of surfactant adsorption on zwitterionic functionalized Al2O3. Sodium dodecyl sulfate was used as a model anionic surfactant, and carboxybetaine methacrylate was used as the zwitterionic material that functionalized half of the alumina surface. The amount of surfactant that adsorbed on the zwitterionic functionalized side was compared to the amount of surfactant adsorbed on the pristine portion of the alumina. The zwitterionic functionalized portion of the alumina surface exhibited enhanced surfactant adsorption, which is mainly due to the configurations of the positive and negative moieties relative to the alumina surface. Factors involving the electrostatic nature of the alumina surface and the flexibility of the zwitterion were discussed. It is also worth noting that the first water layer on top of the alumina surface adsorbs to the surface more strongly than the surfactant anion. The effects of the initial configuration on the surfactant self-assembly process is examined. Several avenues of continued efforts are suggested for future research related to this project.