Sorption of Water and Initial Stages of Swelling of Thin PNIPAM Films Using in Situ GISAXS Microfluidics

Martine Philipp, Volker Körstgens, David Magerl, Christoph Heller, Yuan Yao, Weijia Wang, Gonzalo Santoro, Stephan V. Roth, Peter Müller-Buschbaum

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

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.

Original languageEnglish
Pages (from-to)9619-9627
Number of pages9
JournalLangmuir
Volume31
Issue number35
DOIs
StatePublished - 8 Sep 2015

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