Analysis of the Surface Structure of a Built-Up Film of Fluorocarbon Amphiphile and Polymer/ (Fluorocarbon Amphiphile) Composite Thin Film by Means of X-ray Photoelectron Spectroscopy

Angular dependent X-ray photoelectron spectra were obtained for the Langmuir-Blodgett (LB or built-up) film of a fluorocarbon amphiphile with two fluoroalkyl chains and a poly(vinyl alcohol)/(fluorocarbon amphiphile) composite thin film. A simple layer model was proposed to estimate the photoelectron mean free path in fluorocarbon bilayers. A comparison of the angular dependences of the observed XPS intensity with the calculated intensity for built-up film revealed that the photoelectron mean free path for C_laphotoelectron (kinetic energy of ca. 970 eV) in built-up film is ca. 4.0 nm. Fluorocarbon amphiphilic molecules in the composite thin film form highly oriented bilayer lamella. The surface enrichment of fluorocarbon amphiphile in the surface of the composite thin film facing the air was confirmed by X-ray photoelectron spectroscopy. Application of layer models to the calculation of the composition profile of the composite thin film revealed that the surface of the composite thin film which contains more than 19 wt % amphiphile was completely covered with an oriented bilayer of the amphiphile.