Ionic Effect on Electrochemical Behavior of Water-Soluble Radical Polyelectrolytes

Yanlin Shi, Chanaka J Mudugamuwa, Thidas N Abeysinghe, Yasser S M Alotaibi, Michael J Monteiro, Justin M Chalker, Jodie L Lutkenhaus, Zhongfan Jia

Research output: Contribution to journalArticlepeer-review

Abstract

Water-soluble redox-active polymers (RAPs) have emerged as attractive electroactive materials for aqueous redox flow batteries because these systems rely on readily available size-exclusion membranes rather than expensive ion-selective membranes. While incorporating ionic units is the most effective strategy for forming water-soluble redox polyelectrolytes, little is known about how charges dictate their electrochemical behavior. Here, we design a series of water-soluble TEMPO (2,2,6,6-tetramethylpiperidyl-1-oxy) radical polyelectrolytes with identical radical distribution but various ionic groups through a sequential postmodification method. Physical and electrochemical characterizations show disparate diffusion coefficients (D) and charge transfer kinetics (k0) of these radical polyelectrolytes at various pH. Particularly, pH exerts a strong impact on k0 of the negatively charged polymer (i.e., with carboxylic acid groups). The bimolecular reaction rate kex determined from redox-induced polymer films shows electrostatic interactions between charged segments can enhance the electron self-exchange reaction rate by ten folds. The results suggest that charge effects are of great importance when designing water-soluble redox polymers for electrochemical applications.
Original languageEnglish
Pages (from-to)5733-5743
Number of pages11
JournalMacromolecules
Volume55
Issue number13
DOIs
Publication statusPublished - 12 Jul 2022

Keywords

  • Electrochemical Behaviour
  • Water-Soluble
  • Radical
  • Polyelectrolytes

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