Regensburg 2010 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 10: Poster: Structure and Dynamics of Responsive Hydrogels
CPP 10.1: Poster
Monday, March 22, 2010, 16:30–18:00, Poster C
Temperature dependent switching kinetics and aging effects of gold coated end-capped PNIPAM thin films — •Weinan Wang1, Jan Perlich1, Gunar Kaune1, Achille M. Bivigou Koumba2, Andre Laschewsky2, Christine M. Papadakis1, Robert Cubitt3, and Peter Müller-Buschbaum1 — 1TU München, Physik - Department E13, Garching, Germany — 2Uni. Potsdam, Inst. Chemie, Potsdam-Golm, Germany — 3ILL, Grenoble, France
Poly(N-isopropylacrylamide) (PNIPAM) is one of the prominent thermo-sensitive hydrogels for the construction of nanoscale electric switches which are sensitive to water and to water vapour (humidity). We choose PNIPAM end-capped with n-butyltrithiocarbonate (nbc-PNIPAM), a very short hydrophobic end group, to introduce an internal ordering and increase the mechanical stability in the films without sacrificing the swelling ability seriously. Two different gold layers with 0.4 nm and 5 nm thickness are coated on the nbc-PNIPAM surface by sputtering. The surface structures of the dry films before and after switching are characterized with AFM. The internal structures after each swelling-deswelling cycle are investigated by grazing incidence small angle x-ray scattering (GISAXS). The temperature dependent switching kinetics and aging effects in water vapour of such films is probed by in-situ neutron reflectometry. The real time water diffusion and thickness changes for the two different gold layer thicknesses are compared and discussed in the framework of electric switches applications