Impact of substrate and processing on confinement of nafion thin films

Ahmet Kusoglu, Douglas Kushner, Devproshad K. Paul, Kunal Karan, Michael Anthony Hickner, Adam Z. Weber

Research output: Contribution to journalArticle

82 Citations (Scopus)

Abstract

Thin films of ion-conducting polymers are an important area of study due to their function in many electrochemical devices and as analogues for interfacial phenomena that occur in bulk films. In this paper, the properties of Nafion, a prototypical ionomer, are investigated as thin films (4 to 300 nm) on carbon, gold, and platinum substrates that are fabricated using different casting methods and thermal histories. Specifically, water uptake, swelling, and morphology are investigated by quartz-crystal microbalance, ellipsometry, and grazing-incidence X-ray scattering to develop structure/property/processing relationships. For all substrates, as the films' thickness decreased, there is an initial decrease in swelling followed by a subsequent increase for film thicknesses below ≈20 nm due to a disordering of the film hydrophilic/hydrophobic structure. Decreased swelling and less structural order is observed on gold for spin-cast films compared to self-assembled films; the opposite effect is observed for films on carbon. The presented systematic data set and analyses represent a thorough study of the behavior of Nafion thin films on model substrates of interest in metal catalyst/carbon electrodes, and these insights help to elucidate the underlying polymer physics and confinement effects in these and related systems. Structure-property-processing behavior of Nafion thin films is controlled by a complex interplay between substrate/film interactions, thickness, and casting method. Self-assembled and spin-cast films demonstrate different behavior depending on the substrate. Swelling decreases from the bulk polymer values or films between ≈20 to 100 nm thick and then increases for films thinner than 20 nm, for which phase-separation is weak.

Original languageEnglish (US)
Pages (from-to)4763-4774
Number of pages12
JournalAdvanced Functional Materials
Volume24
Issue number30
DOIs
StatePublished - Aug 13 2014

Fingerprint

Thin films
Substrates
thin films
Processing
swelling
Swelling
Carbon
Gold
Film thickness
casts
carbon
Polymers
Casting
film thickness
polymer physics
gold
Ionomers
perfluorosulfonic acid
Quartz crystal microbalances
Ellipsometry

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Kusoglu, Ahmet ; Kushner, Douglas ; Paul, Devproshad K. ; Karan, Kunal ; Hickner, Michael Anthony ; Weber, Adam Z. / Impact of substrate and processing on confinement of nafion thin films. In: Advanced Functional Materials. 2014 ; Vol. 24, No. 30. pp. 4763-4774.
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Impact of substrate and processing on confinement of nafion thin films. / Kusoglu, Ahmet; Kushner, Douglas; Paul, Devproshad K.; Karan, Kunal; Hickner, Michael Anthony; Weber, Adam Z.

In: Advanced Functional Materials, Vol. 24, No. 30, 13.08.2014, p. 4763-4774.

Research output: Contribution to journalArticle

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AU - Kushner, Douglas

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