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The Partitioning Mechanism of Phenazine Ethosulfate into Polymer Film Electrodes
Author(s) -
Coleman Brian D.
Publication year - 2004
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200302961
Subject(s) - electrochemistry , partition coefficient , polymer , phenazine , glassy carbon , diffusion , electrode , redox , materials science , chemistry , analytical chemistry (journal) , cyclic voltammetry , chemical engineering , inorganic chemistry , thermodynamics , chromatography , organic chemistry , physics , engineering
Phenazine ethosulfate (PES + ) partitioning into the AQ55 cation‐exchange polymer has been demonstrated by immersion and continuous electrochemical cycling experiments. Cyclic voltammetric waveshapes indicate that both the reduction of PES + and the oxidation of PESH are diffusion‐controlled when incorporated into the polymer film. This is in dramatic contrast to the behavior exhibited at bare glassy carbon where the reduction of PES + is diffusion‐controlled but the oxidation of PESH is characteristic of a surface‐confined redox process. The straightforward determination of the partition coefficient is complicated by the uncertainty associated with accurately knowing the thickness of the swollen polymer. Therefore Randles‐Sevcik data for the reduction of PES + at the bare and polymer‐modified electrode were compared to qualitatively assess the extent of possible partitioning, which was determined to be on the order of 10 1 –10 2 . The partition coefficient was determined to be 9.1±0.4, a value in agreement with qualitative assessment. Partitioning was found to be sensitive to the cations present in solution with the order of extractability of PES + from solutions of Li + , Na + , and K + , increasing in the order: Li + >Na + >K + . Continuous cycling experiments suggest PES + partitions into the film during the reductive cycle to restore the equilibrium concentration in the film caused by the electrochemical consumption of the species.