X-ray reflectivity study of fine structure of thin polymer films and polymer assembly at interface

For the purpose of studying the surfaces of both thin films and monolayers on water surface, an apparatus for X-ray reflectometry (XR) has been newly constructed by modification of a theta-theta goniometer. At the sample position, the specially designed LB trough was set for water surface measurements. In the case of a thin poly(vinyl alcohol) film on a glass plate prepared by the spin-coating method, a lot of sharp and clear Kiessig fringes (at least 34th) are observed, indicating an extremely high resolution of our XR apparatus. Similar experiments were also performed for thin multilayer films composed of different kinds of polymers, and the fine structures of these films were precisely determined. XR profiles of distearoylphosphatidylcholine (DSPC), a phospholipid, monolayer on water surface were measured at three different surface pressures. The fringe positions shifted towards the lower angle direction with increasing surface pressure, indicating that the monolayer thickness increases with the increase of surface pressure. (C) 1998 Elsevier Science B.V. All rights reserved.