The 9th International Conference on Multiscale Materials Modeling

Presentation information

Symposium

O. Tribology and Interface: Multi-Scale, Multi-Physics, and Multi-Chemistry Phenomena in Friction, Lubrication, Wear, and Adhesion

[SY-O6] Symposium O-6

Wed. Oct 31, 2018 11:15 AM - 12:30 PM Room5

Chairs: Yoshitaka Umeno(The University of Tokyo, Japan), Yoshinori Shiihara(Toyota Technological Institute,Japan)

[SY-O6] Sliding on physisorbed cetyltrimethylammonium bromide (CTAB)

Johannes Laurin Hoermann, Lars Pastewka (University of Freiburg, Germany)

In solution, amphiphilic surfactants can form physisorbed boundary films on immersed surfaces. A film’s structure and thereby its lubrication performance depend on numerous properties of all involved substances, such as the surface’s potential, as well as surfactant and background electrolyte concentration. We investigate the dependency of the coefficient of friction on adsorption film topography in exemplary contact systems by means of classical all-atom molecular dynamics. For this purpose, the present study focuses on cationic CTAB at idealized aqueous solution-gold interfaces. Recent parametrizations of CTAB, originally intended for micelle modeling in bulk solution, are combined with representations of simple gold surfaces. The stability of differently shaped pre-assembled surface aggregates at various effective surfactant concentrations are compared against expected behavior as documented by abundant experimental contributions. We finally present friction tests in simple shear geometries of surfaces covered with pairwise identical CTAB film morphologies.