Oligoaniline intermediates in the aniline-peroxydisulfate system

Surwade, Sumedh P.; Dua, Vineet; Manohar, Neha; Manohar, Sanjeev K.; Beck, Erling

doi:10.1016/j.synthmet.2008.11.002

Cited by 87 publications

(146 citation statements)

References 52 publications

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“…31 Hence, from the UV-Vis and FTIR results, case (A) samples should be composed of the phenazine-like AN oligomers with some substituted quinones. 14,16,18,30 For case (B), the shape of the spectrum is similar to that obtained from case (A), except that a shifted band at 361 nm (from 371 nm) and a weak broad band B614 nm are observed, which are caused by the para-coupled branches growing from the phenazine-like structures. 20,32 In addition, the color of the test solution is changed from brown for case (A) to olive for case (B).…”

Section: Uv-vis Resultssupporting

confidence: 68%

“…For case (A), the two strong peaks at 277 and 371 nm observed in both doped and dedoped samples are related to the p-p* transitions in substituted quinone. 16,18,30 The peak at 371 nm may also be contributed by phenazine. 31 Hence, from the UV-Vis and FTIR results, case (A) samples should be composed of the phenazine-like AN oligomers with some substituted quinones.…”

Section: Uv-vis Resultsmentioning

confidence: 99%

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Polymerization of aniline under various concentrations of APS and HCl

Tang

Wang

Lin

et al. 2011

Polym J

103

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Effects from various initial molar ratios of aniline (AN), ammonium peroxydisulfate (APS) and HCl ( [AN]: [APS]: [HCl]) on the polymerization of AN were investigated. First, a scheme derived from a molecular point of view was proposed to distinguish formation mechanisms based on their initial conditions. Thereafter, by choosing a relatively low ratio of Keywords: aniline; formation mechanism; phenazine-like oligomers; polyaniline INTRODUCTION Polyaniline (PANI) is one of the most important conducting and semi-conducting polymers widely used in organic optoelectronic devices and has attracted considerable attention recently because of its tunable electrical conductivity, easy preparation from common chemicals and excellent thermal and environmental stabilities. 1,2 The electrical properties of PANI are sensitively dependent on its oxidation and protonation states, of which the emeraldine state (see Figure 1) with a wide range of electrical conductivity can be achieved by simple doping/dedoping chemistry based on acidic/basic reactions. 1-3 The conventional chemical oxidative polymerization of aniline (AN) is carried out in a strong acidic solution and initiated by adding an oxidant (such as ammonium peroxydisulfate, APS). 3 From a technical point of view, the above-mentioned preparation for PANI is a simple process, but the formation mechanism involves an intricate interplay of consecutive chemical and physical reactions. [3][4][5][6][7][8][9][10][11][12] To account for the formation of PANI, the following basic mechanisms were reported. The redox reaction of neutral ANs with APS produces AN radicals. 4 Under a neutral or alkaline condition, the mixed ortho-para coupling of AN radicals together with oxidative intramolecular cyclization forms AN oligomers with phenazine-like structures at the initial stage (see Figures 2a and b for phenazine and phenazine-like trimer). 9-13 The oxidation of AN and AN oligomers with APS both release protons, and the pH of the solution falls. [12][13][14][15][16][17][18][19][20] In a strong acidic environment, the formation of a para-coupled structure

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Section: Uv-vis Resultssupporting

confidence: 68%

Section: Uv-vis Resultsmentioning

confidence: 99%

Polymerization of aniline under various concentrations of APS and HCl

Tang

Wang

Lin

et al. 2011

Polym J

103

View full text Add to dashboard Cite

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“…Aniline droplets serve as oxidation templates and, for that reason oligomers are often produced as microspheres [10]. Their branched structure was proposed to include the quinoneimine groups [22,26].…”

Section: Oligomeric Microspherical Samples Am 02-b and Am 1-bmentioning

confidence: 99%

“…The peak at 1374 cm -1 , typical of a stan- dard PANI base and assigned to C-N stretching in the neighborhood of a quinonoid ring [23], becomes smaller in the products prepared under less acidic conditions, e.g., in acetic acid solutions. The peak located at 1040 cm -1 suggests the presence of sulfonate groups attached to the aromatic rings [8], but sulfate groups have also been proposed as an alternative [22]. The peaks described above have been observed in the FTIR spectra of nanostructured PANI prepared under various conditions by many authors [13,17−22].…”

Section: Introductionmentioning

confidence: 99%

“…Their interpretation and assignment, however, is still open to some discussion. They are also present in the first products of aniline oxidation [8,10,14,19,20,22,24] where aniline oligomers are expected to be generated [22,25,26]. The identification of early-stage intermediate species and their impact on the bulk polymer morphology is of substantial interest.…”

Section: Introductionmentioning

confidence: 99%

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Polyaniline: The infrared spectroscopy of conducting polymer nanotubes (IUPAC Technical Report)

Trchová

Stejskal

2011

Pure and Applied Chemistry

530

241

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Polyaniline (PANI), a conducting polymer, was prepared by the oxidation of aniline with ammonium peroxydisulfate in various aqueous media. When the polymerization was carried out in the solution of strong (sulfuric) acid, a granular morphology of PANI was obtained. In the solutions of weak (acetic or succinic) acids or in water, PANI nanotubes were produced. The oxidation of aniline under alkaline conditions yielded aniline oligomers. Fourier transform infrared (FTIR) spectra of the oxidation products differ. A group of participants from 11 institutions in different countries recorded the FTIR spectra of PANI bases prepared from the samples obtained in the solutions of strong and weak acids and in alkaline medium within the framework of an IUPAC project. The aim of the project was to identify the differences in molecular structure of PANI and aniline oligomers and to relate them to supramolecular morphology, viz. the nanotube formation. The assignment of FTIR bands of aniline oxidation products is reported.

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Polyaniline Nanostructures

Ćirić‐Marjanović

2010

Nanostructured Conductive Polymers

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Polyaniline (PANI) is one of the most extensively studied conducting polymers because of its simple synthesis [1] and doping/dedoping chemistry [2], low cost, high conductivity, and excellent environmental stability. PANI has a wide applicability in rechargeable batteries [3], erasable optical information storage [4], shielding of electromagnetic interference [5], microwave-and radar-absorbing materials [6], sensors [7], indicators [8], catalysts [9], electronic and bioelectronic components [10], membranes [11], electrochemical capacitors [12], electrochromic devices [13], nonlinear optical [14] and light-emitting devices [15], electromechanical actuators [16], antistatic [17] and anticorrosion coatings [18]. Its electromagnetic and optical properties depend mostly on its oxidation state and degree of protonation [19]. The green emeraldine salt form of PANI is conducting ($1-10 S cm À1 for granular powders) [1]. It contains, depending on the synthetic route, variousunits (in the preceeding formulae B, Q and A À denote a benzenoid ring, quinonoid ring and dopant anion, respectively). The blue emer-The preparation of bulk quantities of conducting granular PANI is usually performed Nanostructured Conductive PolymersEdited by Ali Eftekhari by the oxidative polymerization of aniline with ammonium peroxydisulfate (APS) in an acidic aqueous solution (initial pH < 2.0) [1]. Colloidal PANI nanoparticles are prepared by dispersion polymerization of aniline in the presence of various colloidal stabilizers [20,21]. The average size of colloidal PANI nanoparticles decreases with increasing stabilizer/aniline ratio. PANI colloids often have nonspherical (rice grain, needle-like, etc.) core-shell morphology. The colloidal nanoparticle core most likely has a composite nature, i.e. it is composed of both the PANI and the incorporated stabilizer, while the shell is formed by the stabilizer. Nowadays, conducting PANI nanostructures are the focus of intense research owing to their significantly enhanced dispersibility and processability, and substantially improved performance in many applications, in comparison with granular and colloidal PANI [22][23][24][25][26][27]. The continuously growing interest in the study of zero-dimensional (0-D) (solid nanospheres), one-dimensional (1-D) (nanofibers (nanowires), nanorods (nanosticks), nanoneedles, rice-like nanostructures, nanotubes), two-dimensional (2-D) (nanoribbons (nanobelts), nanosheets (nanoplates, nanoflakes, nanodisks, leaf-like nanostructures), nanorings (cyclic nanostructures), net-like nanostructures), and three-dimensional (3-D) PANI nanostructures (hollow nanospheres, dendritic and polyhedral nanoparticles, flower-like, rhizoid-like, brain-like, urchin-like, and star-like nanostructures, etc.) has dramatically increased in recent years (Figure 2.1). The major focus of research has been the preparation, characterization, processing, and application of PANI nanofibers (PANI-NFs) and nanotubes (PANI-NTs). PANI-NFs are 1-D PANI nanoobjects of cylindrical profile with diameters ...

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Oligoaniline intermediates in the aniline-peroxydisulfate system

Cited by 87 publications

References 52 publications

Polymerization of aniline under various concentrations of APS and HCl

Polymerization of aniline under various concentrations of APS and HCl

Polyaniline: The infrared spectroscopy of conducting polymer nanotubes (IUPAC Technical Report)

Polyaniline Nanostructures

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