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