Optimum reaction conditions for the polymerization of aniline in aqueous solution by ammonium persulphate

Armes, Steven P.; Miller, John F.

doi:10.1016/0379-6779(88)90109-9

Cited by 195 publications

(68 citation statements)

References 23 publications

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“…Protonation by H 2 S0 4 The chemical structure of H 2 SO 4 protonated polyemeraldine and the structural changes associated with its step-wise deprotonation, as revealed by the Nls core-level line shape, are similar to those observed in the HCl or HBr protonated sample. core-level spectra for a typical H 2 S0 4 protonated polyemeraldine.…”

Section: Profanation By Hbrmentioning

confidence: 52%

ESCA Studies of Protonation in Polyaniline

Kang

Neoh

Tan

1989

Polym J

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ABSTRACT:The structural changes associated with the protonation of polyemeraldine base by various protonic acids were studied by X-ray photoelectron spectroscopy (XPS). The imine, amine and positively charged nitrogen corresponding to a particular oxidation state and protonation level were quantitatively differentiated in the properly deconvoluted NI s core-level spectrum. The actual degree of protonation in the HCI and HBr complexes was determined from the halogen anion core-level component. The anion in the H 2SO4 complex was found to be the monovalent HSO4 -species. Treatment of the HBr, HNO3, and H2SO4 protonated polyemeraldine with HCI readily resulted in the exchange of the anion species.KEY WORDS X-Ray Photoelectron Spectroscopy / Polyemeraldine / Protonation / Chemical Structure / Recent interest in the electroactive polymers1 has resulted in renewed interest 2 -4 in the century-olds aniline family of polymers. The conductive polyaniline complexes can be prepared either by chemical 4 or electrochemical6·7 polymerization and oxidation. The polymers are basically poly(p-phenylene amine imine)s in which the oxidation state of the polymer can be varied from the fully reduced poly(p-phenylene amine) or "leucoemeraldine" to the fully oxidized poly(p-phenylene imine) or "pernigraniline". The 50% oxidized polymer has been termed an "emeraldine base". Each oxidation state can exist in the form of its base or protonated form by treatment of the base with an acid. 2 · 3The structures of the polyaniline complexes have been studied by various analytical techniques.8 -ii A number of oligomeric model compounds of aniline have also been investigated.12 -is A number of recent reports have been devoted to the use of electron spectroscopy for chemical analysis (ESCA) or X-ray photoelectron spectroscopy (XPS) technique to characterize polyanilines. 7 · 12 · 16 -19 However, the chemical structure associated with a particular redox state, such as the relative amounts of benzoid amine, quinoid imine and positively charged nitrogen, has yet to be determined quantitatively and unambiguously. The present XPS study indicates that the three nitrogen species can be quantitatively differentiated in the N 1 s core-level spectrum. This allow the investigation of structural changes associated with protonation and deprotonation of polyaniline.

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Section: Profanation By Hbrmentioning

confidence: 52%

ESCA Studies of Protonation in Polyaniline

Kang

Neoh

Tan

1989

Polym J

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“…Peroxydisulfate is the most commonly used oxidant, and its ammonium salt was preferred to the potassium counterpart because of its better solubility in water. The concentration of aniline hydrochloride was set to 0.2 M. Various oxidant/monomer ratios have been used in the literature [15]. To minimize the presence of residual aniline and to obtain the best yield of PANI, the stoichiometric peroxydisulfate/aniline ratio 1.25 is recommended [15] (Fig.…”

Section: Project Descriptionmentioning

confidence: 99%

Polyaniline. Preparation of a conducting polymer(IUPAC Technical Report)

Stejskal

Gilbert

2002

Pure and Applied Chemistry

1,228

569

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Eight persons from five institutions in different countries carried out polymerizations of aniline following the same preparation protocol. In a "standard" procedure, aniline hydrochloride was oxidized with ammonium peroxydisulfate in aqueous medium at ambient temperature. The yield of polyaniline was higher than 90 % in all cases. The electrical conductivity of polyaniline hydrochloride thus prepared was 4.4 ± 1.7 S cm-1 (average of 59 samples), measured at room temperature. A product with defined electrical properties could be obtained in various laboratories by following the same synthetic procedure. The influence of reduced reaction temperature and increased acidity of the polymerization medium on polyaniline conductivity were also addressed. The conductivity changes occurring during the storage of polyaniline were monitored. The density of polyaniline hydrochloride was 1.329 g cm-3. The average conductivity of corresponding polyaniline bases was 1.4 x108 S cm-1, the density being 1.245 g cm-1. Additional changes in the conductivity take place during storage. Aging is more pronounced in powders than in compressed samples. As far as aging effects are concerned, their assessment is relative. The observed reduction in the conductivity by ~10 % after more than one-year storage is large but, compared with the low conductivity of corresponding polyaniline (PANI) base, such a change is negligible. For most applications, an acceptable level of conductivity may be maintained throughout the expected lifetime.

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“…A distinctive feature of polyaniline among the conducting polymers is that its conductivity is not only controlled by the degree of chain oxidation but also by the level of protonation in {l (-B-NH-B-NH-)y (-B-N=Q=N-)1-yl (HA)Q,, (15,16 (17). After a thorough washing with water, the materials were dried under vacuum.…”

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confidence: 99%

Conducting Polyaniline Filaments in a Mesoporous Channel Host

Bein

1994

Science

1,119

594

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Conducting filaments of polyaniline have been prepared in the 3-nanometer-wide hexagonal channel system of the aluminosilicate MCM-41. Adsorption of aniline vapor into the dehydrated host, followed by reaction with peroxydisulfate, leads to encapsulated polyaniline filaments. Spectroscopic data show that the filaments are in the protonated emeraldine salt form, and chromatography indicates chain lengths of several hundred aniline rings. The filaments have significant conductivity while encapsulated in the channels, as measured by microwave absorption at 2.6 gigahertz. We have demonstrated previously the encapsulation of several different conjugated polymers such as polypyrrole and pyrolyzed polyacrylonitrile in the well-defined channels of zeolite molecular sieves (7-10). The template synthesis of conducting polymers in the much larger, random pores (about 0.1 to 1 pm) of insulating host membranes has also been described (11). Networks of poly(3-methylthiophene) dendrites have been grown between electrodes (12). We have now achieved the stabilization of conducting polyaniline filaments in the ordered, 3-nm-wide hexagonal channels of the mesoporous aluminosilicate host (13, 14) MCM-41. We were able to demonstrate the ac conductivity of such encapsulated filaments of nanometer dimensions.A distinctive feature of polyaniline among the conducting polymers is that its conductivity is not only controlled by the degree of chain oxidation but also by the level of protonation in {l (-B-NH-B-NH-)y (-B-N=Q=N-)1-yl (HA)Q,, (15,16 (Fig. 2). The similarity of the ring and C-H bending modes between PANI-loaded host (PANI-MCM) and emeraldine salt, seen in their Raman spectra (Fig. 3) 4.6, 3.4 (shoulder), and 1.6 eV, typical for the band-gap and polaron transitions of emeraldine salt (20). The encapsulated, evacuated polymer shows a single, fairly broad (8 G) electron spin resonance line at g = 2.0032, suggesting slightly lower protonation levels than in emeraldine salt (21) or dipolar interactions with the MCM channel walls.The relative chain length of intrachannel polyaniline [versus polystyrene (PS) (Fig. 4). If we assume a polymer density of 1.3 g/cm3 (23), the loading of 0.28 g per gram of host closely corresponds to the change in poros- Fig. 1. Reaction scheme for the encapsulation of polyaniline in the channels of

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Optimum reaction conditions for the polymerization of aniline in aqueous solution by ammonium persulphate

Cited by 195 publications

References 23 publications

ESCA Studies of Protonation in Polyaniline

ESCA Studies of Protonation in Polyaniline

Polyaniline. Preparation of a conducting polymer(IUPAC Technical Report)

Conducting Polyaniline Filaments in a Mesoporous Channel Host

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