A new inverse emulsion protocol has been developed for the synthesis of polyaniline (PANI), which can be dissolved completely in common organic solvents such as chloroform. Benzoyl peroxide is used as the oxidizing agent and toluene + 2-propanol-water is used as the solvent. Dodecylbenzenesulfonic acid (DBSA) has been selected as the dopant because it also functions as the surfactant. Cyclic voltammetry and spectroelectrochemical investigations were carried out to study the electroactivity, UV-Vis response, and metal-to-insulator transition of the chemically synthesized PANI as a function of applied electrode potential. At more positive potentials, cyclic voltammograms of PANI in aqueous acids show two oxidation waves caused by redox processes of PANI as observed with electrochemically prepared PANI. Peak position and shape are influenced by the slow anion exchange rate. Electrical conductivity of the material is relatively high as the minimum resistance value is nearly 10 Ω. SEM investigations show that the amount of DBSA in the feed strongly influences the morphology of the polymer. In situ UV-Vis spectroscopy measurements reveal good electrochromic reversibility for the polymer very similar to the response of PANI synthesized electrochemically.

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Dodecylbenzenesulfonic acid (DBSA) dissolved in 2-propanol (70% solution), a surfactant and dopant, is used in the synthesis of polyaniline (PANI) colloids. The micelle-aided synthesis yields green dispersions that do not undergo macroscopic precipitation for more than a year. UV-vis studies reveal that polymerization is completed in 3 h irrespective of the feed ratio of DBSA/aniline. The polymerization yield depends on the amount of DBSA in the feed. UV-vis spectroscopy as a function of applied potential was carried out for the first time for thin layers of the dispersion. Bands corresponding to both emeraldine salt and emeraldine base were observed during cathodic potential sweeps whereas in an anodic sweep bands due to only emeraldine base were observed. Electronic absorption spectroscopy and preresonance Raman spectroscopy as a function of pH indicate emeraldine salt (metal) to emeraldine base (insulator) transformation at higher pH (pH 9-10). The high aggregation tendency of PANI particles during solvent drying yields particles with irregular shapes.

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Corrosion protection performance of a completely soluble polyaniline-dodecylbenzenesulfonic acid salt (PANI-DBSA) on C45 steel has been studied with electrochemical impedance and potentiodynamic measurements. Chloroform is the most suitable solvent to process the pristine PANI-DBSA because of negligible interaction of the solvent with the polyaniline (PANI) backbone. An anodic shift in the corrosion potential (E = ~70 mV), a decrease in the corrosion current and a significant increase in the charge transfer resistance indicate a significant anti-corrosion performance of the soluble PANI deposited on the protected steel surface.Corrosion protection follows the mechanism of formation of a passive oxide layer on the surface of C45 steel. In situ UV-Vis spectroscopy was used to investigate the differences in permeability of aqueous anions into PANI-DBSA. Preliminary results of electron diffraction studies show that PANI-DBSA possesses an orthorhombic type of crystal structure. An increase in the feed ratio of DBSA to aniline increases the tendency of aggregation of spherical particles of PANI obvious in transmission electron microscopy. PANI-DBSA slowly loses its electrochemical activity in acid free electrolyte without undergoing degradation.2