Title In-situ characterization of the temperature-sensitive swelling behavior of poly(N-isopropylacrylamide) brushes by infrared and VIS ellipsometry
Date 31.08.2013
Number 35102
Abstract In-situ infrared-spectroscopic characterization of polymer brushes plays an important role for a deeper understanding of the brushes' structural and chemical properties during stimuli-induced switching experiments. In this work, we used infrared-spectroscopic ellipsometry (IR-SE) to investigate the temperature-dependent swelling behavior of poly(N-isopropylacrylamide) [PNIPAAm] brushes below and above their lower critical solution temperature. IR-SE spectra were evaluated using optical-layer calculations in order to determine swollen-brush thickness and water content inside the brush. For a ddry = 12.6 nm thin PNIPAAm brush, we found swollen- and deswollen-brush thicknesses of respectively (43 ± 8) nm and (20 ± 9) nm, which is in good agreement with ellipsometry results in the visible (VIS) spectral range. We determined water contents of (86 ± 13) % and (68 ± 15) %, and by correlating IR-SE with VIS-ellipsometric measurements, we were even able to obtain values of up to 2 % accuracy.
Publisher Thin Solid Films
Citation Thin Solid Films 541 (2013) 41-45
Authors Furchner, A. ; Bittrich, E. ; Uhlmann, P. ; Eichhorn, K.-J. ; Hinrichs, K.

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