Chemical Oxidative Polymerization of Methylene Blue: Reaction Mechanism and Aspects of Chain Structure.

Yaroslav O Mezhuev,Ruslan A Alekperov,Efrem G Krivoborodov,Alexander A Artyukhov,Alexander L Kovarskii,Irina S Ionova,Igor A Derevnin,Mikhail I Shtilman,Yuri V Korshak,Ilya Y Toropygin,Ivan V Plyushchii,Mikhail V Motyakin,Igor Y Vorobev,Mikhail A Volkov,Anna L Luss,Valerie A Dyatlov

doi:10.3390/polym13132188

Abstract

The kinetic regularities of the initial stage of chemical oxidative polymerization of methylene blue under the action of ammonium peroxodisulfate in an aqueous medium have been established by the method of potentiometry. It was shown that the methylene blue polymerization mechanism includes the stages of chain initiation and growth. It was found that the rate of the initial stage of the reaction obeys the kinetic equation of the first order with the activation energy 49 kJ · mol−1. Based on the proposed mechanism of oxidative polymerization of methylene blue and the data of MALDI, EPR, and IR spectroscopy methods, the structure of the polymethylene blue chain is proposed. It has been shown that polymethylene blue has a metallic luster, and its electrical conductivity is probably the result of conjugation over extended chain sections and the formation of charge transfer complexes. It was found that polymethylene blue is resistant to heating up to a temperature of 440 K and then enters into exothermic transformations without significant weight loss. When the temperature rises above 480 K, polymethylene blue is subject to endothermic degradation and retains 75% of its mass up to 1000 K.

Highlights

The ability to control the properties and morphology of thin films of electroactive polymethylene blue [1] during the electrochemical polymerization of methylene blue [2] opens up prospects for the use of this polymer
Films based on polymethylene blue have a high conductivity of about 103 S · cm−1, which is of interest for the creation of conducting glasses [15]
Polymethylene blue can be synthesized by chemical oxidation of methylene blue by the action of ammonium peroxodisulfate [9]

Summary

Introduction

The ability to control the properties and morphology of thin films of electroactive polymethylene blue [1] during the electrochemical polymerization of methylene blue [2] opens up prospects for the use of this polymer. Research aimed at establishing the laws of synthesis and properties of polymethylene blue is still not enough, it has already found application for the manufacture of electrochemical sensors. The successful use of polymethylene blue for the detection of natural substances, such as catechins in green tea [7], pyridoxine [8], DNA [9], hemoglobin [10], and xanthan and uric acid [11], give hope for the creation of new analyzers for medical and biological purposes. Polymethylene blue can be synthesized by chemical oxidation of methylene blue by the action of ammonium peroxodisulfate [9]

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Conclusion