Berlin 2018 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 21: Focus: Smart Hydrogels and Hydrogel Based Devices I - organized by Gerald Gerlach, Walter Richtering and Thomas Hellweg
CPP 21.10: Talk
Tuesday, March 13, 2018, 12:15–12:30, C 130
Water uptake and diffusion in thin PNIPAM microgel films — •Tobias Widmann1, Lucas Kreuzer1, Nuri Hohn1, Lorenz Bießmann1, Kun Wang1, Jean-François Moulin2, Yvonne Hertle3, Thomas Hellweg3, and Peter Müller-Buschbaum1 — 1TU München, Physik-Department, LS Funktionelle Materialien, 85748 Garching — 2HZG at MLZ, 85747 Garching — 3Universität Bielefeld, Fakultät für Chemie, Physikalische und Biophysikalische Chemie III, 33615 Bielefeld
Microgels out of thermoresponsive polymers show a strong change in volume by a variation of the temperature across the lower critical solution temperature (LCST), which in a thin film geometry translates into a change of the film thickness. This offers new functionality and is of high interest e.g. for biomedical applications. In order to gain detailed insights in the kinetics during the volume change, the diffusion of water molecules through the interconnected polymer network during the uptake and release of water is analyzed. Thin PNIPAM microgel films crosslinked with N,N'-methylenebisacrylamide are investigated with time-of-flight neutron reflectometry (TOF-NR). H2O and D2O are used to apply different humidity conditions at a constant temperature below the LCST of PNIPAM. The H2O and D2O swelling as well as the H2O - D2O and D2O - H2O exchange processes are studied. Results from the TOF-NR analysis are modelled with a model which accounts for the temporal evolution of the humidity.