ELLIPSOMETRIC STUDY OF BINARY MIXED FILMS OF POLY(ETHYLENE OXIDE) AND POLY(METHYL METHACRYLATE) AT THE AIR-WATER-INTERFACE

Binary mixtures of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) spread at the air/water interface have been investigated by using ellipsometry and surface pressure measurements. From the surface pressure measurements both polymers were found to be compatible. This result correlates well with the compatibility of the blends of PEO and PMMA in the bulk state. Ellipsometry gave two quantities for the phase difference (∆) between the parallel and perpendicular components of the reflected light and the azimuth (ψ) of the amplitude ratio for light polarized parallel and normal to the plane of incidence. The value of ∆ was much more sensitive to the presence of polymers at the air/water interface as compared to the value. The changes in ∆ and δ∆ between pure water and the water surface covered with polymers increased with an increase in the amount spread and approached a plateau value around the PMMA surface concentration of 1.7 mg/m2 in the mixtures, irrespective of the mixed ratio. Their plateau values did not change if the surface concentration was further increased. © 1990, American Chemical Society. All rights reserved.