Switching Anionic and Cationic Semipermeability in Partially Hydrolyzed Polyacrylonitrile: A pH-Tunable Ionic Rectifier

Luthando Tshwenya, Frank Marken, Klaus Mathwig, Omotayo A. Arotiba

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2 Citations (Scopus)


Membrane materials with semipermeability for anions or for cations are of interest in electrochemical and nanofluidic separation and purification technologies. In this study, partially hydrolyzed polyacrylonitrile (phPAN) is investigated as a pH-switchable anion/cation conductor. When switching from anionic to cationic semipermeability, also the ionic current rectification effect switches for phPAN materials deposited asymmetrically onto a 5, 10, 20, or 40 μm diameter microhole in a 6 μm thick polyethylene-terephthalate (PET) film substrate. Therefore, ionic rectifier behavior can be tuned and used to monitor and characterize semipermeability. Effects of electrolyte type and concentration and pH (relative to the zeta potential at approximately 3.1) are investigated by voltammetry, chronoamperometry, and impedance spectroscopy. A computational model provides good qualitative agreement with the observed electrolyte concentration data. High rectification effects are observed for both cations (pH > 3.1) and anions (pH < 3.1) but only at relatively low ionic strengths.

Original languageEnglish
Pages (from-to)3214-3224
JournalACS Applied Materials and Interfaces
Issue number2
Early online date18 Dec 2019
Publication statusPublished - 15 Jan 2020


  • double layer
  • ion channel
  • ion gating
  • ionic rectifier
  • membrane
  • polyacrylonitrile
  • steady state voltammetry

ASJC Scopus subject areas

  • Materials Science(all)

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