Berlin 2008 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 31: Thin Films
CPP 31.5: Talk
Thursday, February 28, 2008, 10:30–10:45, C 264
Temperature dependent swelling behavior of PNIPAM based block copolymer films — •Weinan Wang1, Peter Müller-Buschbaum1, Kordelia Troll1, Amit Kulkarni1, Christine Papadakis1, Achille M. Bivigou Koumba2, and Andre Laschewsky2 — 1TU München, Physik - Department E13, James-Franck-Str. 1, D-85747 Garching — 2Potsdam Universität, Inst. Chemie, Karl-Liebknecht-Str. 24-25, D-14476 Potsdam-Golm
PNIPAM is one of the prominent stimuli-sensitive hydrogels because it has a relatively low collapse transition temperature at 32°C. To introduce an internal ordering and increase the mechanical stability in the films, the homopolymer is typically replaced by PNIPAM based block copolymers. We focus on how the internal structures depend on the temperature in the swollen state and how the transition temperature depends on the initial film thickness. The films are freshly made by spin coating. For the investigation of the morphologies of the films at different temperatures in the swollen state, especially the changes of internal structures, grazing incidence small angle X-ray scattering (GISAXS) and transmission X-ray scattering are performed. To detect the possible shift of the transition temperature with film thickness, in-situ ellipsometry is applied. It is observed that both the size and the ordering of internal structures are changed at the transition temperature. The transition temperatures of the films depend strongly on the initial film thickness and are significantly different from those of the bulk materials. In addition, atomic force microscopy (AFM) and X-ray reflectivity are also used for characterization.