Formation Mechanism of Polyaniline Nanotubes by a Simplified Template‐Free Method

Ding, Hongyan; Shen, Junyao; Wan, Meixiang; Chen, Zhaojia

doi:10.1002/macp.200700624

Cited by 135 publications

(117 citation statements)

References 41 publications

(26 reference statements)

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“…10,12,14,18,21 The peaks at 757, 740 and 696 cm À1 are related to the monosubstituted aromatic rings, which is associated with AN oligomers. 12,[17][18][19] As shown in Figure 6, the intensity of these eight peaks decreases slightly as [HCl] increases from 0 to 0.10 M. This phenomenon can be explained by the reduction in the availability of neutral ANs because of the increase of [HCl] and hence a decrease of the redox reaction. Thus, the signals associated with ortho-coupled phenazine-like structure and AN oligomers decrease.…”

Section: Resultsmentioning

confidence: 82%

“…[9][10][11][12][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 is then favored. 4,9 The subsequent polymerization processes result in emeraldine salt (ES) PANI.…”

Section: Introductionmentioning

confidence: 99%

“…[10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] In general, there are three experimental approaches to study the effects from the acidic environment. [5][6][7][10][11][12][13][14][15][16][17][18][19][20][21] For the first approach, using automatic titration to control a constant pH, effects of pH on the morphological evolution of PANI nanostructures were discussed. 21 For the second approach, by adopting [APS]/[AN]¼1 or 1.25 in weak acidic or alkaline mediums (that is, starting with high pH), the properties of products obtained at various moments during the strong pH falling were investigated.…”

Section: Introductionmentioning

confidence: 99%

“…21 For the second approach, by adopting [APS]/[AN]¼1 or 1.25 in weak acidic or alkaline mediums (that is, starting with high pH), the properties of products obtained at various moments during the strong pH falling were investigated. [5][6][7][10][11][12][13][14][15][16][17][18][19][20] For the third approach, by choosing [APS]/[AN]¼0.25-1. 25, effects of terminal pH on the final products were analyzed.…”

Section: Introductionmentioning

confidence: 99%

“…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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Polymerization of aniline under various concentrations of APS and HCl

Tang

Wang

Lin

et al. 2011

Polym J

102

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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: Resultsmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Polymerization of aniline under various concentrations of APS and HCl

Tang

Wang

Lin

et al. 2011

Polym J

102

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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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Nanofibers of Conducting Polymer Nanocomposites

Kondawar¹,

Agrawal²

2013

Responsive Materials and Methods

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Formation Mechanism of Polyaniline Nanotubes by a Simplified Template‐Free Method

Cited by 135 publications

References 41 publications

Polymerization of aniline under various concentrations of APS and HCl

Polymerization of aniline under various concentrations of APS and HCl

Polyaniline Nanostructures

Nanofibers of Conducting Polymer Nanocomposites

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