Sorption of Water and Initial Stages of Swelling of Thin PNIPAM Films Using in Situ GISAXS Microfluidics.
The sorption of low-molecular penetrants by thin polymer films, as well as structural changes provoked therein, is of high relevance for many fields of application. Complex permeation, diffusion, swelling, and dissolution processes are often induced within films by solvents or gases. Here, we use a novel in situ microfluidics-grazing incidence small-angle X-ray scattering (GISAXS) setup to examine changes in film thickness and in the surface structure of a thin polymer film that sorbs a good solvent. Thus, this technique is highly complementary to the established techniques on the field of diffusion in polymers. The initial stages of water uptake and swelling are resolved for a 50 nm thin, hydrophilic poly(N-isopropylacrylamide) (PNIPAM) film, before its dissolution sets in. The initial stages of swelling are tentatively described by anomalous swelling induced by a time- and space-dependent diffusion coefficient.
Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München , James-Franck-Strasse 1, D-85748 Garching, Germany.
Martine
M
Philipp
Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München , James-Franck-Strasse 1, D-85748 Garching, Germany.
Volker
V
Körstgens
Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München , James-Franck-Strasse 1, D-85748 Garching, Germany.
David
D
Magerl
Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München , James-Franck-Strasse 1, D-85748 Garching, Germany.
Christoph
C
Heller
Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München , James-Franck-Strasse 1, D-85748 Garching, Germany.
Yuan
Y
Yao
Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München , James-Franck-Strasse 1, D-85748 Garching, Germany.
Weijia
W
Wang
Photon Science, Deutsches Elektronen-Synchrotron (DESY) , Notkestrasse 85, D-22607 Hamburg, Germany.
Gonzalo
G
Santoro
Photon Science, Deutsches Elektronen-Synchrotron (DESY) , Notkestrasse 85, D-22607 Hamburg, Germany.
Stephan V
SV
Roth
Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München , James-Franck-Strasse 1, D-85748 Garching, Germany.
Peter
P
Müller-Buschbaum