X-ray structure of polyaniline

Pouget, J. P.; Józefowicz, M. E.; Epstein, Arthur J.; Tang, Xinyi; MacDiarmid, A. G.

doi:10.1021/ma00003a022

Cited by 1,342 publications

(826 citation statements)

References 16 publications

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“…It can be inferred from the X-rays patterns that PANI films present a higher degree of crystallinity than the substituted polymer. These diffractograms are similar to those obtained by Pouget et al 15,16 for PANI and ring substituted polyanilines. Those authors have performed an exhaustive analysis of the X-rays patterns of polyaniline family and they concluded that bulky substituint groups lead to an increased disorder due to defects in stacking of the polymeric chains.…”

Section: Thermal Studysupporting

confidence: 88%

Structural, morphological and spectroelectrochemical characterization of poly (2-ethyl aniline)

Schemid

Torresi

Bassetto

et al. 2000

J. Braz. Chem. Soc.

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Neste trabalho foi feito um estudo comparativo da estrutura, morfologia e resposta espectroeletroquímica da poli (2-etilanilina) e da polianilina em função do contra-íon. Os ácidos minerais conferem uma estrutura mais esponjosa a filmes de poli (2-etilanilina) enquanto que ácidos orgânicos tornam a estrutura homogênea e compacta. Para a poli (2-etilanilina) a resposta eletroquímica depende muito da relação carga/tamanho do eletrólito utilizado, devido a efeitos estéricos e eletrônicos. As relações entre as bandas de absorção e os pares redox mostram que mudanças na absorbância são proporcionais a corrente faradaica que é observada nos voltamogramas.In this paper a comparative study of the structure, morphology, and the spectroelectrochemical response of poly (2-ethyl aniline) and polyaniline for different counterions is presented. Spongeous structure of poly (2-ethyl aniline) is obtained when mineral acids are used, while homogeneous and compact films are formed using organic acids. The electrochemical response of poly (2-ethyl aniline) depends on the charge/size ratio of the counterion due to both steric and electronic effects. The correlation between the absorption bands and the redox couple show that the changes in absorbance are proportional to the faradaic current observed in the voltammograms.

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Section: Thermal Studysupporting

confidence: 88%

Structural, morphological and spectroelectrochemical characterization of poly (2-ethyl aniline)

Schemid

Torresi

Bassetto

et al. 2000

J. Braz. Chem. Soc.

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“…42 This crystallinity is caused by the counter-ions (Cl À or HSO 4 À ) accompanying the protons near the N atoms (see Figure 1 for PANI with polarons and bipolarons), which provide the necessary electrostatic forces for inducing a higher degree of chain ordering. 42,43 After the dedoping process to remove these absorbed dopants, the ordering between these chains is reduced and thus the EB PANI samples become amorphous as shown in Figure 11b.…”

Section: Xrd Resultsmentioning

confidence: 99%

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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“…1, the generalized Polyaniline Emeraldine-base form (EB-PANI, blue, undoped) possesses equal amount of imine and amine nitrogen and it can be doped using protonic acids, leading to Emeraldine-salt form (ES-PANI, green, doped). Thus, EB-PANI and ES-PANI assume different types of crystalline arrangements depending on the used synthetic route and neutralization process [9,10].…”

Section: Introductionmentioning

confidence: 99%