Dresden 2006 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 12: POSTER Colloids, Nanoparticles and Self-Organizing Systems

CPP 12.9: Poster

Tuesday, March 28, 2006, 17:00–19:00, P3

The scattering from thin, lamellar diblock copolymer films in the distorted-wave Born approximation — •Christine M. Papadakis¹, P. Busch², M. Rauscher³, D.-M. Smilgies², and D. Posselt⁴ — ¹Physikdepartment E13, TU München, James-Franck-Str. 1, D-85747 Garching — ²Cornell University, Ithaca NY, USA — ³MPI für Metallforschung und Universität Stuttgart — ⁴Roskilde University, Denmark

Grazing-incidence small-angle X-ray scattering (GISAXS) of thin films of diblock copolymers reveals information about the ordering and preferential orientations of the phase-separated microdomains within the films. The grazing-incidence geometry enhances the surface sensitivity; however, the scattering cannot be described any more with a simple kinematic theory, as in transmission small-angle scattering.

We have calculated the scattering cross-section in the framework of the distorted-wave Born approximation, a dynamical scattering theory. We treat the case of thin films of lamellar diblock copolymers, where the orientation of the lamellae is either perpendicular or parallel to the film interfaces and compare the predictions to experimental results from thin films of poly(styrene-b-butadiene) diblock copolymers. For perpendicular lamellae, Bragg rods are found, which are extended along the film normal, whereas for parallel lamellae, intensity maxima appear along the film normal. The positions of these maxima can be explained by accounting for refraction at the film surface and reflection at the film-substrate interface.