Order and orientation in self-assembled long chain alkanephosphate monolayers adsorbed on metal oxide surfaces

Octadecylphosphoric acid ester was employed to establish monolayers on vari ous flat oxide substrates. The films were prepared via self-assembly from a heptane/propan-2-ol solution. The alkanephosphate was found to produce ori ented, well-ordered films on titanium oxide, niobium. oxide, and aluminum o xide surfaces. Contact-angle measurements and near-edge X-ray absorption fi ne structure spectroscopy (NEXAFS) indicate that these layers closely resem ble those formed by a similar thiol-gold system, with respect to packing de nsity, inclination, and molecular order. The preparation scheme appears to be rather universally applicable to a variety of metal oxide substrates. Th ese systems show promise as an approach to functionalizing different oxide surfaces with well-ordered organic monolayers, with potential applications in the fields of corrosion protection, adhesion promotion, biochemical anal ysis, and sensors.