Fluorinated Monomolecular Assemblies: Model Systems to Probe Chemical Interactions at the Polymer-Metal Interface

Abstract

AbstractMonomolecular assemblies of n-perfluorocarboxylic acids [CF3(CF2)nCOOH, n=6, 7, and 8] have been adsorbed at silver by spontaneous adsorption from dilute alcoholic solutions. Infrared reflection spectroscopy indicates that the monolayers form by the reactive chemisorption of the carboxylic acid to a carboxylate salt. Ellipsometrically-determined film thicknesses increase linearly with an increase in the perfluorocarbon chain length. Contact angle measurements indicate that the packing density of the films increases with increasing chain length, resulting in an interface with a low surface free energy. The structure and properties of these interfaces are compared to those for monolayers of n-alkanoic acids. The potential utility of such assemblies to probe fundamental chemical and physical interactions at polymer-metal interfaces are also discussed.