8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P7.82Thu 811:10-14:00Computational studies ob behavior of sodium dodecylsulfate at rutile/water interfacesEdgar Nunez Rojas 1 and Hector Dominguez 11 Instituto de Investigaciones en Materiales, UNAM, Universidad Nacional Autonoma deMexico. Coyoacan. , 04510, Mexico, D. F, MexicoA series of molecular dynamics simulations to study behavior of an anionic surfactant near to realsurfaces were carried out. Each surface was modelled using different crystallographic orientationsof rutile, namely (001), (100) and (110). Surfactant molecules near to the surface aggregate indifferent ways, depending on properties of the surfaces. Even though all three surfaces are madeof the same atoms, orientation is a key to determine adsorption. Structure of aggregated moleculesand its formation were studied with density profiles of both polar groups and no polar groups,coverage and geometric parameters. Moreover, a well defined adsorpted layer in each systemwas observed. It was found that when there are oxygen atoms on solid surface of rutile, surfactantmolecules are attached to surface along sited between the lines of these atoms. Both average lengthand angle profiles for hydrocarbon chains were calculated in order to determine the influence of thesolid surface on the surfactant molecules. In simulation on surface with (100) orientation surfactantmolecules showed a formation of a structure which was approximated to a segment of a cylinderformed by molecules attached to the solid surface by their hydrocarbon chains. On the otherhand, in the system simulated on the solid surface (110) some molecules were attached to solid bytheir polar groups and remainder molecules structured in a structure which was approximated to asegment of a sphere.82