Quartz crystal microbalance with coupled spectroscopic ellipsometry-study of temperature-responsive polymer brush systems

Stefan Adam, Meike Koenig, Keith Brian Rodenhausen, Klaus Jochen Eichhorn, Ulrich Oertel, Mathias Schubert, Manfred Stamm, Petra Uhlmann

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

Using a combined setup of quartz crystal microbalance with dissipation monitoring together with spectroscopic ellipsometry, the thermo-responsive behavior of two different brush systems (poly(N-isopropyl acrylamide) and poly(2-oxazoline)s) was investigated and compared to the behavior of the free polymer in solution. Poly(2-oxazoline)s with three different hydrophilicities were prepared by changing the content of a hydrophilic comonomer. While both polymer types exhibit a sharp, discontinuous thermal transition in solution, in the brush state the transition gets broader in the case of poly(N-isopropyl acrylamide) and is transformed into a continuous transition for poly(2-oxazoline)s. The position of the transition in solution is influenced by the degree of hydrophilicity of the poly(2-oxazoline). The difference in areal mass detected by quartz crystal microbalance and by spectroscopic ellipsometry, has been attributed to the chain segment density profile of the polymer brushes. Applying this density profile information, for poly(N-isopropyl acrylamide) two different swelling stages could be identified, while for poly(2-oxazoline) the transition between a parabolic and more step-wise profile is found continuous. The different swelling characteristics were attributed to the different miscibility behavior types, with the brush state acting similar to a crosslinked system.

Original languageEnglish (US)
Pages (from-to)843-851
Number of pages9
JournalApplied Surface Science
Volume421
DOIs
StatePublished - Nov 1 2017

Keywords

  • Poly(2-oxazoline)
  • Poly(N-isopropyl acrylamide)
  • Quartz crystal microbalance
  • Spectroscopic ellipsometry
  • Temperature-sensitive polymer brushes

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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