Autogenous Oxidation/Reduction of Polyaniline in Aqueous Sulfuric Acid

Processes

Arindam Sarkar¹  Vinay Juvekar¹  Asfiya Contractor²  Ravindra Kale²  Amrita Singh² 

[1] Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India;Department of Fibers and Textile Processing Technology, Institute of Chemical Technology, Mumbai 400019, India;

关键词: intrinsically conducting polymers;    polyaniline;    highly conjugated polymer;    autogenous oxidation/reduction;    open circuit potential;    equilibrium potential;   

DOI  :  10.3390/pr10030443

来源: DOAJ

【 摘 要 】

In this work, we have shown through open circuit potential experiments that in aqueous sulfuric acid solutions, a thick polyaniline film undergoes autogenous oxidation when reduced below a threshold potential and autogenous reduction when oxidized above the threshold potential. This phenomenon is associated with the high resonance stability of polarons in long polyaniline chains present in thicker films. We have determined the rates of these reactions using a linear sweep chronopotentiometry technique. We propose that the oxidation reaction of polyaniline produces polarons with a concomitant reduction of hydrogen ions to hydrogen radicals, which further combine with each other to produce the hydrogen molecule in the absence of dissolved oxygen. On the other hand, at high potentials polarons are reduced with the concomitant oxidation of water to hydroxyl radicals. Both the radicals are stabilized due to the interaction of their unpaired electrons with pi-electrons of the aromatic rings of the polymer backbone. At the equilibrium value of the open circuit potential, both the hydrogen radicals and hydroxyl radicals are generated at equal rates and react with each other to form water.

【 授权许可】

Unknown