INORGANIC MONOLAYERS FORMED AT AN ORGANIC TEMPLATE - A LANGMUIR-BLODGETT ROUTE TO MONOLAYER AND MULTILAYER FILMS OF ZIRCONIUM OCTADECYLPHOSPHONATE

Single-layer and multilayer films of zirconium octadecylphosphonate ha ve been prepared on silicon oxide surfaces and characterized by Langmu ir-Blodgett (LB) transfer data, contact angle, ATR-FTIR, XPS, ellipsom etry and X-ray diffraction. The deposition method uses a preformed, or ganized organic template for assembling the inorganic lattice by combi ning LB and self-assembly (SA) techniques. First, an LB template of oc tadecylphosphonic acid is formed on an octadecyltrichlorosilane-covere d substrate, then Zr4+ ions are ''self-assembled''from solution. A cap ping octadecylphosphonic acid LB monolayer is added to complete the bi layer. Transfer of the phosphonic acid is continuous with transfer rat ios ranging between 1.1 and 1.2. Contact angle measurements on a compl eted bilayer give an advancing contact angle of 112 +/- 1-degrees. The asymmetric methylene (nu(a)(CH2)) band of the template layer appears at 2918 cm-1 and possesses a fwhm of 20 cm-1 indicating that an all-tr ans, close-packed template is formed. The frequency and shape of the n u(a)(CH2) band remain unchanged in the progression from the template l ayer to bilayer to multilayers. XPS analysis of the zirconated LB temp late shows a 1:1 ratio of Zr:P, while bilayer and multilayer films pos sess a Zr:P ratio of 1:2 consistent with the stoichiometry observed in solid zirconium phosphonate. Ellipsometry shows a layer-by-layer incr ease in film thickness corresponding to a bilayer thickness of 51 angs trom, while X-ray diffraction reveals a d spacing of 52 angstrom and t hus demonstrates the layered nature of the films. The zirconium phosph onate films are quite insoluble in both water and organic solvents.