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A Redox Conjugated Polymer-Based All-Solid-State Reference Electrode

Department of Chemistry, Oakland University, Rochester, MI 48309, USA
Department of Chemistry, Michigan Technological University, Houghton, MI 49931, USA
Author to whom correspondence should be addressed.
Polymers 2018, 10(11), 1191;
Received: 28 September 2018 / Revised: 19 October 2018 / Accepted: 21 October 2018 / Published: 25 October 2018
(This article belongs to the Special Issue Redox Polymers for Energy Storage)
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This work reports the design, synthesis, and characterization of a novel redox-active conjugated polyaniline containing quinone moiety as a solid state reference electrode. The union of electro-active quinone with π-conjugated polyaniline was created by the first chemical synthesis of para-dimethoxybenzene-functionalized aniline as a monomer using a palladium-mediated coupling. The successful polymerization of the as-prepared monomer was accomplished without acid additives. Its post-polymerization modification with strong Lewis acid boron tribromide furnished unique poly (aniline quinone/hydroquinone) with desired properties for all-solid-state reference electrode (RE) applications. The electrochemical responses from the conjugated polyaniline backbone in this unique polymer have been “suppressed” by the quinone pendant. The resulting poly (aniline quinone) showed a quasi-reversible redox process from the redox behavior of the pendant quinone. The stable electrode potential of this poly (aniline quinone/hydroquinone) suggested that it was a single phase in which the amounts of totally reduced and totally oxidized species could be maintained at a constant in various solvents and electrolytes. Its electrochemical stability was excellent with 95% peak current retention after continuous cyclic voltammetric testing. The aniline and quinone moieties in poly (aniline quinone/hydroquinone) render it to have both hydrophilic and hydrophobic compatibility. It showed excellent behavior as a reference electrode in aqueous and non-aqueous media and can be used in both non-zero current and zero-current conditions, providing a stable potential with a maximum potential drift of ~4.7 mV over ten consecutive days. View Full-Text
Keywords: redox conjugated polymer; polyaniline; electro-polymerization; quinone; reference electrode redox conjugated polymer; polyaniline; electro-polymerization; quinone; reference electrode

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Qu, K.; Fang, M.; Zhang, S.; Liu, H.; Zeng, X. A Redox Conjugated Polymer-Based All-Solid-State Reference Electrode. Polymers 2018, 10, 1191.

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