RRS characterization of selected oligomers of polyaniline in situ spectroelectrochemical study

Boyer, M. I.; Quillard, S.; Cochet, M.; Louarn, G.; Lefrant, S.

doi:10.1016/s0013-4686(98)00307-7

Cited by 38 publications

(36 citation statements)

References 19 publications

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“…3). Previous studies 37 are dominated by strong peaks resulting from resonance enhancement of the highly symmetric 8a (C ar -C ar stretching), 9a (C ar -H bending) and N-SQ (stretching) vibrations. Two pairs of bands correspond to 8a and 9a vibrations located at 1610-1595 and 1190-1160 cm 1 , respectively.…”

Section: Acid-h 2 O Systemsmentioning

confidence: 94%

Protonation, sol formation and precipitation of poly‐ and oligoanilines

Grüger

Khalki

Colomban

2003

J Raman Spectroscopy

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Raman spectrometry, UV-visible-near IR and attenuated total reflection IR absorptions are used to analyze the protonation of the emeraldine form of the phenyl/ -NH 2 end-capped BQBBa tetramer and of the phenyl/ -NH 2 end-capped (BQBB) 4 a hexadecamere in strong (H 2 SO 4 or HCl), intermediate (CH 3 COOH) and weak (CH 3 OH) acids. Evolution of the pristine solution with aqueous dilution and time is analyzed in order to understand the formation of a sol of nanofilaments, which agglomerate and finally precipitate. Water in an acidic solution favors the precipitation of the corresponding emeraldine salt material, i.e. increases the degree of aggregation of the oligomeric species and the aromatic behavior of the rings. The secondary doping effect consists in intercalation of water molecules in the highly aggregated (paramagnetic) species, strongly bound to the oligomeric units and whose removal is always accompanied by elimination of the protonating agent (primary doping). The role of interchain interactions in charge carrier mobility appears more important than that of intrachain behavior.

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Section: Acid-h 2 O Systemsmentioning

confidence: 94%

Protonation, sol formation and precipitation of poly‐ and oligoanilines

Grüger

Khalki

Colomban

2003

J Raman Spectroscopy

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“…Since the electrode potential can be controlled continuously, these spectroelectrochemical experiments could provide with information on either distinctness or continuity of redox transformations between different forms of polyaniline. A number of papers deal with various aspects of in situ Raman spectroelectrochemistry of polyaniline [12][13][14][15][16][17][18][19][20], some of its derivatives [20][21][22][23] and model compounds [24]. Gradual changes in Raman spectra have been observed as a function of increasing electrode potential [15], and a large variety of different segments, differing in their redox state, has been claimed to exist at any potential [17].…”

Section: Introductionmentioning

confidence: 99%

Raman spectroelectrochemical study of polyaniline and sulfonated polyaniline in solutions of different pH

Mažeikienė

Tomkutė

Kuodis

et al. 2007

Vibrational Spectroscopy

101

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“…When compared to the Raman spectrum of pure powder B5 in Figure 2a, even though almost all the bands are slightly red-shifted all spectroscopic features of the molecules are preserved, (Figure 3b) are assigned to semiquinone species. [21][22][23][24] The band at 1636 cm −1 can be assigned to a radical cation species that formed. 21,24 The other bands arising in this spectrum are 1603 cm (very weak).…”

Section: Resultsmentioning

confidence: 99%

“…Figure 4a shows a Raman spectrum of B4Q1 drop cast from methanol onto a glass substrate, while Figure 4b shows a Raman spectrum of B4Q1 drop-cast from methanol onto a steel substrate (native oxide) and Figure 4c to the semiquinone species. [21][22][23][24] The band at 1498 cm −1 still belongs to B4Q1 but the bands at 1568 and 1180 cm −1 are an indication that B4Q1 tends to transform into the fully oxidized form (B3Q2) upon exposure to methanol. It means that B4Q1 molecules change their oxidation states in part to semiquinone and in part to B3Q2 through interaction with methanol.…”

Section: Resultsmentioning

confidence: 99%

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Interactions of Different Redox States of Phenyl-Capped Aniline Tetramers with Iron Oxide Surfaces and Consequences for Corrosion Inhibition

Chowdhury

Mohtasebi

Kostina

et al. 2017

J. Electrochem. Soc.

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The phenyl capped aniline tetramer (PCAT) is known for its redox properties and is being studied for its ability to inhibit corrosion of iron and steel in addition to being of interest for sensors and molecular electronics. Here we investigate the interactions, orientation and corrosion inhibition ability of all three oxidation states of the free base form of PCAT with iron oxide surfaces. Raman spectroscopy demonstrates interconversion of these molecules to one another due to charge transfer to the surface. Polarized mid-IR spectroscopy and atomic force microscopy were used to elucidate the molecular orientations on the surface. Electrochemical impedance spectroscopy shows the corrosion resistance of fully reduced PCAT coatings on low carbon steel to be higher than that for half-oxidized and fully oxidized PCAT coatings. A weight loss test, laser line measurements and Raman spectroscopy reveal that even though half-oxidized PCAT initially shows a lower corrosion resistance due to transformation into the fully oxidized form, with time it transforms back into the half-oxidized form and protects the surface. Fully oxidized PCAT molecules show opposite behavior, causing the degradation of the surface over time. We thus attained a deeper insight into the interplay of the different oxidation states for corrosion control. Polyaniline (PANI) is a prominent member of the conducting polymer family because of its diverse application in biosensors, 1 electrochromic devices, 2 fuel cells, 3,4 etc. One of the most studied applications of this polymer is corrosion inhibition of metals. DeBerry showed in 1985 that PANI can inhibit corrosion of iron and steel by passivating the surface in acidic media. [5][6][7] Similarly to the native oxides, the passive oxides on iron or steel maintain a layered structure of a fully oxidized outer layer, followed by an intermediate mixed iron (II) and iron (III) oxide layer transitioning to a very thin inner iron (II) oxide layer next to the bulk metal. PANI is mainly found in three different stable oxidation states (fully reduced or leucoemeraldine, half-oxidized or emeraldine, and fully oxidized or pernigraniline) and several protonation states. The complete mechanism behind the corrosion inhibition ability of this polymer is still unclear due to its complex chemistry. PANI coatings can break down catastrophically, which is the reason why their commercialization has failed. Recent work demonstrated that this breakdown happens due to a high conductivity and long-range electronic interactions.8 Even though historically it had been assumed that conductivity is essential to the inhibition mechanism, recent work has shown that conductivity of pure PANI coatings and PANI containing coatings can be interrupted by sparse addition of small PANI particles without hurting corrosion inhibition efficiency.9-11 Oligoanilines do not share certain drawbacks intrinsic to PANI coatings (e.g. catastrophic failure, poor solubility). Very little work has been done on oligoanilines, which have related physical a...

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RRS characterization of selected oligomers of polyaniline in situ spectroelectrochemical study

Cited by 38 publications

References 19 publications

Protonation, sol formation and precipitation of poly‐ and oligoanilines

Protonation, sol formation and precipitation of poly‐ and oligoanilines

Raman spectroelectrochemical study of polyaniline and sulfonated polyaniline in solutions of different pH

Interactions of Different Redox States of Phenyl-Capped Aniline Tetramers with Iron Oxide Surfaces and Consequences for Corrosion Inhibition

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