Berlin 2015 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 35: P7: Hydrogels and Elastomers
CPP 35.1: Poster
Dienstag, 17. März 2015, 14:00–16:00, Poster C
Demixing transition and molecular interactions in poly(N-isopropyl acrylamide) compared to its monomer — •Moritz Futscher1, Martine Philipp1, Peter Müller-Buschbaum1, and Alfons Schulte2 — 1TU München, Physik-Department, LS Funktionelle Materialien, James-Franck-Str. 1, 85748 Garching — 2University of Central Florida, Department of Physics, The College of Optics & Photonics, Orlando, Florida 32817-2385, US
Temperature-sensitive hydrogels such as poly(N-isopropyl acrylamide) (PNIPAM) exhibit a coil to globule transition of the polymer chains with a lower critical solution temperature (LCST) near 32 °C. The cooperative dehydration of bound water molecules upon heating plays a significant role. The hydrogen bonding with the amide groups in the side chains has to be contrasted with the hydration interaction of the hydrophobic main chain hydrocarbons. Employing FTIR spectroscopy we probe molecular changes in the various chemical groups. PNIPAM and its monomer NIPAM are investigated at a concentration of 20 wt% in aqueous solution. We observe a nearly discontinuous shift of the peak frequencies and the intensities of vibrational bands (amide I, amide II, CH) in PNIPAM, while in NIPAM there is a continuous linear shift with temperature. The results are discussed with respect to hydration changes in the amide group and cooperative interactions with bound water along the backbone chain.