Salt Sensitivity of the Thermoresponsive Behavior of PNIPAAm Brushes

Meike Koenig, Keith Brian Rodenhausen, Sebastian Rauch, Eva Bittrich, Klaus Jochen Eichhorn, Mathias Schubert, Manfred Stamm, Petra Uhlmann

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


We report investigations on the salt sensitivity of the thermoresponsive behavior of PNIPAAm brushes applying the quartz crystal microbalance coupled with spectroscopic ellipsometry technique. This approach enables a detailed study of the optical and mechanical behavior of the polymer coatings. Additional conclusions can be drawn from the difference between both techniques due to a difference in the contrast mechanism of both methods. A linear shift of the phase-transition temperature to lower temperatures with the addition of sodium chloride was found, similar to the behavior of free polymer chains in solution. The thermal hysteresis was found to be decreased by the addition of sodium chloride to the solution, hinting to the interaction of the ions with the amide groups of the polymer, whereby the formation of hydrogen bonds is hindered. The results of this study are of relevance to the application of PNIPAAm brushes in biological fluids and demonstrate the additional potential of the ion sensitivity besides the better known thermosensitivity.

Original languageEnglish (US)
Pages (from-to)2448-2454
Number of pages7
Issue number7
StatePublished - Feb 20 2018

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry


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