Berlin 2012 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 20: (Hydro)gels and Elastomers
CPP 20.3: Talk
Wednesday, March 28, 2012, 10:00–10:15, C 264
A comparison of the morphology and thermoresponsive switching behavior in thin films of cyclic and linear poly(N-isopropylacrylamide) — •David Magerl1, Xing-Ping Qiu2, Françoise M. Winnik2, and Peter Müller-Buschbaum1 — 1TU München, Physik -Department, LS Funktionelle Materialien, James-Franck-Str. 1, 85748 Garching, Germany — 2Université de Montréal, Faculty of Pharmacy and Department of Chemistry, CP 6128 Succursale Centre Ville Montréal QC H3C 3J7, Canada
Stimuli-responsive hydrogels are of increasing interest because of their use in a variety of applications such as switches and sensors. Poly(N-isopropylacrylamide) (PNIPAM) is one of the most studied polymers in this context. However, there are only very few studies on cyclic PNIPAM, although this topology is of great interest because of the absence of end-groups, which has a significant impact on the lower critical solution temperature (LCST).
In this study, we compare the properties of spin-coated thin films of cyclic and linear PNIPAM samples with similar molecular weights and a low polydispersity. The film thickness is varied and the films are characterized with x-ray reflectivity and optical microscopy. The swelling behavior of these films, exposed to water vapor, is investigated as a function of film thickness in order to assess the influence of chain topography on the thin film behavior. Additionally, the interface correlation between the surface and the substrate is probed with grazing incidence small-angle x-ray scattering.