Soft x-ray diffraction studies on polymeric Langmuir-Blodgett films

Abstract

X-ray reflectivity studies were performed on a series of homopolymers and copolymers with hydrophilic spacers which were prepared on quartz substrates as Langmuir-Blodgett films. Soft X-rays of 1560eV energy were used to enhance spatial resolution without requiring stringent collimation conditions. Specular reflectivity profiles, obtained under θ-2θ conditions, were obtained for a series of multilayers and monolayers of the polymers. Calculated refelctivity profiles, using a multilayer model of the electron density, were in good agreement with the experimental data. The spacing in the Langmuir-Blodgett multilayers was found to increase linearly, to within a first approximation, with the length of the main chain spacer. From the intensity of the peaks in the reflectivity profiles it was evident that the multilayers did not have ideally planar interfaces. The degree of non-planarity was not found to be a function of the chain spacer. © 1991.