Adhesion of Sodium Dodecyl Sulfate Surfactant Monolayerswith TiO2(Rutile and Anatase) Surfaces.

Surfactants are widely used as templatesto control the nucleationand growth of nanostructured metal oxides such as titania. To gaininsight into the origin of the surfactant–titania interactionsresponsible for polymorph and orientation selection, we simulate theself-assembly of an anionic surfactant monolayer on various low-indextitania surfaces, for a range of densities. We characterize the bindingin each case and compute the adhesion energies, finding anatase (100)and rutile (110) to be the strongest-binding surfaces. The sodiumcounterions in the monolayer are found to dominate the adhesion. Itis also observed that the assembly is directed predominantly by surface-monolayerelectrostatic complementarity. Incorporating water displacement intothe calculations does not alter the general findings but does causethe adhesion energies to fall within a smaller range. [ABSTRACT FROM AUTHOR]