INTERFACES AND THIN POLYMER FILMS AS SEEN BY X-RAY AND NEUTRON REFLECTIVITY TECHNIQUE. Manfred Stamm, Max Planck-Institut für Polymerforschung, Postfach 3148, 55021 Mainz, Germany

Interfaces between compatible or incompatible polymers play an important role for the understanding of polymer blend properties and adhesion. They are investigated by neutron reflectivity with a resolution of the order of 1nm/1, 2/, where a contrast between components is generated by selective deuteration. Specific examples are discussed including the very early stages of the interdiffusion of compatible polymers at an interface as well as the formation of a narrow interfacial region between strongly incompatible materials, where the interface width depends on compatibility, molecular weight and temperature. Also the interfacial segregation of a compatibalizer such as a diblock copolymer can be followed choosing a suitable contrast against the homopolymers.

X-ray reflectivity on the other hand reveals information on structural aspects within thin films and at the surface/3/. An example is the development of steps at the surface of a combined liquid crystalline polymer during the evolution of smectic order within the film, where the smectic layers are ordered parallel to the surface depending on film thickness. Those reflectivity experiments should be complemented by other investigations as for instance atomic force microscopy, which provides also a lateral resolution.

/1/ M. Stamm, in Physics of Polymer Surfaces and Interfaces, I.C. Sanchez (ed.),

/2/ M. Stamm, D.W. Schubert, Annu.Rev.Mater.Sci 25 (1995) 325

/3/ G. Henn, H. Poths, M. Stamm, Polymers for Adv. Techn. 5 (1994) 582.