Acta Phys. -Chim. Sin. ›› 2009, Vol. 25 ›› Issue (06): 1053-1058.doi: 10.3866/PKU.WHXB20090623

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Molecular Dynamics Simulation of Sodium Dodecyl Benzene Sulfonate Aggregation on Silica Surface

SONG Qi-Sheng, GUO Xin-Li, YUAN Shi-Ling, LIU Cheng-Bu   

  1. Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan 250100, P. R. China
  • Received:2009-02-02 Revised:2009-03-20 Published:2009-06-05
  • Contact: YUAN Shi-Ling E-mail:shilingyuan@sdu.edu.cn

Abstract:

We performed molecular dynamics (MD) simulations to investigate anionic surfactant sodium dodecyl benzene sulfonate (SDBS) adsorption onto a silica surface from solution. Various water phases of different thickness were constructed to investigate the difference between the solid/liquid and the air/liquid interface. We found that surfactant molecules adsorbed on silica surfaces within a short simulation time and they formed a surfactant layer via an interaction between the hydrophobic alkyl chain and the SiO2 surface. With an increase in water phase, one hemi-cylindrical micelle with a hydrophobic core formed on the SiO2 surface when a large amount of surfactant molecules adsorbed. The potential of mean force potential between the polar head of the surfactant and Na + ions or water molecules shows that the dissociation energy barrier is much larger than the combination energy barrier leading to more Na+ ions gathering around the polar head and fewer Na+ in solution. SDBS and water molecules can form complexes through H-bonding at the air/liquid or solid/liquid interface. Simulation results show that molecular dynamics can be used as an adjunct and can provide necessary information for microstructural property experiments.

Key words: Solid/liquid interface, Anionic surfactant, Molecular dynamics simulation

MSC2000: 

  • O641