Potassium iodate–initiated polymerization of aniline

Abstract

Potassium iodate-initiated polymerization of aniline was carried out in an acidified aqueous medium in the presence and in the absence of sodium thiosulfate salt. The nature of the polyaniline (PANI) produced depended on the aniline/potassium iodate (A/PI) mole ratio. Green emeraldine salt (ES) and blue pernigraniline salt (PS) were produced at A/PI mole ratios greater than 2 and less than 2, respectively. The sodium thiosulfate salt played a significant role in the purification and properties of PANI. The optimum aniline-to-oxidant mole ratio was found to be 2 : 1. Spectral, thermal, and electrical characteristics and viscosity of the materials were studied and compared with the results. A reaction scheme has been proposed to elucidate the role of iodine(V). Sodium thiosulfate makes it easier for iodine to be separated from a system and increases the conductivity of the products.

Chemical Polymerization Kinetics of Poly-O-Phenylenediamine and Characterization of the Obtained Polymer in Aqueous Hydrochloric Acid Solution Using K2Cr2O7as Oxidizing Agent

“…Both of the monomer and HCl concentrations are fixed at 0.1 M while the oxidant concentrations were varied from 0.04 to 0.5 M at 5 ± 0.2 ∘ C to investigate the optimum polymerization condition of K 2 Cr 2 O 7 . The yield-time curve was represented in Figure 1, from which it is clear that the obtained yield increased with the increase of K 2 Cr 2 O 7 reaching maximum value at 0.3 M. From the left part of the curve it is clear that the polymer yield increases from 0.04 M to 0.3 M then decreases from 0.3 M to 0.5 M. This could be due to the fact that, in the first part of the curve, the produced initiator ion radical moieties activate the backbone and simultaneously produced the o-phenylenediamine ion radical, which takes place immediately, and, therefore, yield increases with the increase of potassium dichromate concentration up to 0.3 M. But in the second part of the curve, the polymer yield decreases with increasing K 2 Cr 2 O 7 concentration, may be due to a high concentration of oxidant promote the formation of low molecular weight oxidation product and also degrade the product polymer which easily soluble in water [13]. Figure 2, from which it is clear that the obtained yield increases in the acid concentration range from 0.04 to 0.2 then decreases gradually up to 0.5 M. This behavior may be due to, at higher concentration of HCl, the degradation of the polymer in the early stages of the reaction, which may be due to the hydrolysis of polyemeraldine chain [13].…”

“…Polymerization of conducting polymer may be performed by chemical [11] or electrochemical [12] methods. Various chemical oxidizing agents, such as potassium dichromate [13], potassium iodate [14], hydrogen peroxide [15], ferric chloride, or ammonium persulphate, were used [16]. The applications of polyaniline are limited due to its poor processability [17], which is true for most conducting polymers.…”

Synthesis of polyaniline nanoparticle grafted silica gel and study of its Cr(VI) binding property

“…A UV‐Vis spectrum of the prepared polyaniline is shown in Figure 2. The spectrum exhibited sharp absorption peaks at 495 nm, which could be assigned to protonated polyaniline nanoparticles 28. The size of the PANI remains within 100 nm as evident from TEM picture (Fig.…”

“…The FTIR spectrum of the synthesized PANINP‐ g ‐SSG (Fig. 1) exhibited several characteristic peaks of PANI28 (3458, 2588, 804 cm −1 ) and SSG27 (1338, 1060 cm −1 ). A new peak appears at 594 cm −1 , which is absent in the spectrum of both PANI and SSG.…”

Polymers for the Extraction of Chromium—Role of Polymers in the Removal and Recovery of Chromium from Wastewater

“…The chemical structure of polyaniline (PANI) in acid medium is suitable for adsorbing chromate (68). However, very few works (69) on Cr(VI) adsorption by PANI has been reported.…”