Attenuated total reflectance (ATR) study of polymer blend films

Variable angle ATR was used to obtain a compositional depth profile of films cast from the blend solutions. Blend solutions were prepared from a colloid of high molecular weight styrene–acrylate–methacrylic acid copolymer, an alkali-soluble styrene–acrylic acid resin neutralized with ammonia and a colloid of copolymer of propylene. Films obtained from drying the blend solutions show a nonhomogeneous distribution of three polymers through the film thickness. This inhomogeneity cannot be explained solely on the basis of sedimentation effects due to density differences between three polymers. Experimental results of ATR using germanium and KRS-5 crystals are compared to provide estimates of the distance over which nonhomogeneous composition occurs.