Structural Transitions During Formation and Rehydration of Proton Conducting Polymeric Membranes

Marco Viviani, Paola Lova, Giuseppe Portale*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Knowledge of the transitions occurring during the formation of ion-conducting polymer films and membranes is crucial to optimize material performances. The use of non-destructive scattering techniques that offer high spatio-temporal resolution is essential to investigating such structural transitions, especially when combined with complementary techniques probing at different time and spatial scales. Here, a simultaneous multi-technique study is performed on the membrane formation mechanism and the subsequent hydration of two ion-conducting polymers, the well-known commercial Nafion and a synthesized sulfonated poly(phenylene sulfide sulfone) (sPSS). The X-ray data distinguish the multi-stage processes occurring during drying. A sol-gel-membrane transition sequence is observed for both polymers. However, while Nafion membrane evolves from a micellar solution through the formation of a phase-separated gel, forming an oriented supported membrane, sPSS membrane evolves from a solution of dispersed polyelectrolyte chains via formation of an inhomogeneous gel, showing assembly and ionic phase separation only at the end of the drying process. Impedance spectroscopy data confirm the occurrence of the sol-gel transitions, while gel-membrane transitions are detected by optical reflectance data. The simultaneous multi-technique approach presented here can connect the nanoscale to the macroscopic behavior, unraveling information essential to optimize membrane formation of different ion-conducting polymers.

Original languageEnglish
Article number2000717
Number of pages13
JournalMacromolecular Rapid Communications
Volume42
Issue number12
Early online date16-May-2021
DOIs
Publication statusPublished - Jun-2021

Keywords

  • in situ GISAXS
  • GIWAXS
  • membrane formation mechanisms
  • nafion
  • nanomorphology
  • proton exchange polymers
  • sol&#8208
  • gel transition
  • PERFLUORINATED IONOMER MEMBRANES
  • FUEL-CELL APPLICATIONS
  • SMALL-ANGLE SCATTERING
  • X-RAY-SCATTERING
  • ELECTROLYTE MEMBRANES
  • EXCHANGE MEMBRANES
  • NAFION MEMBRANES
  • MORPHOLOGY
  • NEUTRON
  • TRANSPORT

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