Electrochemically controlled swelling and mechanical properties of a polymer nanocomposite

Daniel J. Schmidt, Fevzi Ç Cebeci, Z. Ilke Kalcioglu, Samantha G. Wyman, Christine Ortiz, Krystyn J. Van Vliet, Paula T. Hammond

Research output: Contribution to journalArticlepeer-review

110 Scopus citations

Abstract

We present the layer-by-layer assembly of an electroactive polymer nanocomposite thin film containing cationic linear poly(ethyleneimine) (LPEI) and 68 vol % anionic Prussian Blue (PB) nanoparticles, which allow for electrochemical control over film thickness and mechanical properties. Electrochemical reduction of the PB doubles the negative charge on the particles, causing an influx of water and ions from solution to maintain electroneutrality in the film; concomitant swelling and increased elastic compliance of the film result. Reversible swelling upon reduction is on the order of 2-10%, as measured via pectroscopic ellipsometry and electrochemical atomic force microscopy. Reversible changes in the Young's elastic modulus of the hydrated composite film upon reduction are on the order of 50% (from 3.40 to 1.75 GPa) as measured with in situ nanoindentation, and a qualitative increase in viscous contributions to energy dissipation upon redox is indicated by electrochemical quartz crystal microbalance. Electrochemical stimuli maintain a mild operating environment and can be applied rapidly, reversibly, and locally. We maintain that electrochemical control over the swelling and mechanical behavior of polymer nanocomposites could have important implications for responsive coatings of nanoscale devices, including mechanically tunable surfaces to modulate behavior of adherent cells.

Original languageEnglish (US)
Pages (from-to)2207-2216
Number of pages10
JournalACS nano
Volume3
Issue number8
DOIs
StatePublished - Aug 25 2009

Keywords

  • Electrochemistry
  • Layer-by-layer thin film
  • Nanoindentation
  • Polymer nanocomposite
  • Prussian Blue
  • Responsive materials
  • Swelling

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