Reduced in-plane swelling of Nafion by a biaxial modification process

Steffen Hink, Dirk Henkensmeier, Jong Hyun Jang, Hyoung Juhn Kim, Jonghee Han, SukWoo Nam

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


A biaxial modification process to reduce the in-plane swelling of perfluorosulfonic acid polymers is demonstrated for Nafion 212 membranes. The process is based on the one-way shape memory effect of the polymer, which can be installed by drying under constrained conditions and observed by water swelling. The through-plane/in-plane swelling ratio at 30 °C for treated Nafion 212 increases from 1.4 to 5.8 (ex situ) and ≈25 (after humidity cycling in a fuel cell). Young modulus and tensile strength increase. X-ray diffraction analysis shows an increase of crystallinity. The influence on through- and in-plane proton conductivity is studied. Finally, fuel cell tests are presented. The results suggest that the process enhances the durability of fuel cell systems under changing humidity conditions. A one-way shape memory effect is used to change the direction of water-induced membrane swelling from in-plane to through-plane. Because membranes are clamped between bipolar plates in a fuel cell, the shape memory effect is re-established when membranes dry. This prevents the membrane expanding and forming wrinkles, and therefore could significantly increase the lifetime of fuel cells.

Original languageEnglish
Pages (from-to)1235-1243
Number of pages9
JournalMacromolecular Chemistry and Physics
Issue number11
Publication statusPublished - 2015 Jun 1


  • direction of swelling
  • ionomers
  • polymer electrolyte membrane fuel cell
  • shape memory effect
  • wide-angle x-ray scattering

ASJC Scopus subject areas

  • Materials Chemistry
  • Polymers and Plastics
  • Organic Chemistry
  • Physical and Theoretical Chemistry
  • Condensed Matter Physics


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