Dresden 2009 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
CPP: Fachverband Chemische Physik und Polymerphysik
CPP 28: POSTERS Interfaces and Thin Films
CPP 28.20: Poster
Mittwoch, 25. März 2009, 17:00–19:00, P3
Internal structure of PNIPAM microgel particles — •Martin Medebach1, Anna Burmistrova1, Matthias Karg1, Yvonne Hertle2, Weinan Wang3, Peter Müller-Buschbaum3, and Regine v. Klitzing1 — 1Technische Universität Berlin — 2Universität Bayreuth — 3Technische Universtät München
Thermosensitive microgel particles are of great interest in basic research and also for technical applications. For instance Poly-(N-Isopropylacrylamide), PNIPAM, undergoes a temperature induced phase transition at approx. 32 °C. This transition leads to shrinking by a factor of 10, while the shrinking effect at the solid/liquid interface is only about factor 2 perpendicular to the surface. These findings raise the question how the interactions with the solid surface affect the internal structure of the microgel particles. We report about experiments (GISANS, SANS, AFM and ellipsometry) with charged PNIPAM microgel particles (diameter in bulk between 100 to 1000 nm, depending on the degree of swelling) adsorbed on oppositely charged Silicon wafers. The PNIPAM particles are copolymerized with 5% acrylic acid and they are adsorbed on top of a Silicon wafer that is coated with Polyethyleneimine (PEI). The particles are close packed. From ellipsometry and AFM measurement the swelling is observed normally and laterally (AFM) to the surface. SANS experiments show the correlation length in the bulk system while GISANS measure the correlation length of the absorbed particles in lateral direction. Taken all experiments together we can describe the change of the internal structure during the swelling.