On the swelling behavior of poly(N-Isopropylacrylamide) hydrogels exposed to perfluoroalkyl acids

Dustin T. Savage, Nicolas J. Briot, J. Zach Hilt, Thomas D. Dziubla

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Per- and polyfluoroalkyl substances (PFAS) have rapidly accumulated in the environment due to their widespread use prior to commercial discussion in the early 21st century, and their slow degradation has magnified concerns of their potential toxicity. Monitoring their distribution is, therefore, necessary to evaluate and control their impact on the health of exposed populations. This investigation evaluates the capability of a simple polymeric detection scheme for PFAS based on crosslinked, thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) hydrogels. Surveying swelling perturbations induced by several hydrotropes and comparable hydrocarbon analogs, tetraethylammonium perfluorooctane sulfonate (TPFOS) showed a significantly higher swelling ratio on a mass basis (65.5 ± 8.8 at 15°C) than any of the other analytes tested. Combining swelling with the fluorimetric response of a solvachromatic dye, nile red, revealed the fluorosurfactant to initiate observable aggregation (i.e., its critical aggregation concentration) at 0.05 mM and reach saturation (i.e., its charge neutralization concentration) at 0.5 mM. The fluorosurfactant was found to homogeneously distribute throughout the polymer matrix with energy dispersive X-ray spectroscopy, marking the swelling response as a peculiar nexus of fluorinated interfacial positioning and delocalized electrostatic repulsion. Results from the current study hold promise for exploiting the physiochemical response of PNIPAM to assess TPFOS's concentration.

Original languageEnglish
Pages (from-to)289-299
Number of pages11
JournalJournal of Polymer Science
Issue number4
StatePublished - Feb 15 2021

Bibliographical note

Funding Information:
Access to characterization instruments and staff assistance was provided by the Electron Microscopy Center at the University of Kentucky, supported in part by the National Science Foundation/EPSCoR Award No. 1355438 and by the Commonwealth of Kentucky. Research reported was supported by National Institute of Environmental Health Sciences/NIH grant P42ES007380. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

Publisher Copyright:
© 2021 Wiley Periodicals LLC


  • fluorosurfactants
  • hydrogels
  • per- and polyfluoroalkyl substances
  • poly(N-isopropylacrylamide))
  • surfactant-induced swelling

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Materials Chemistry


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