EPR and electrical conductivity in microporous polyaniline

Langer, Jerzy J.; Krzyminiewski, Ryszard; Kruczyński, Z.; Gibiński, T.; Czajkowski, Igor; Framski, Grzegorz

doi:10.1016/s0379-6779(00)00362-3

Cited by 29 publications

(12 citation statements)

References 9 publications

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“…spin concentration has increased by about 2 orders of magnitude. The change in concentration of polarons and effect of oxygen exposure on it in HCl doped polyaniline and in microporous polyaniline samples have also been reported earlier (Kang et al 1999;Langer et al 2001).…”

Section: Resultssupporting

confidence: 68%

Electrical transport and EPR investigations: A comparative study for d.c. conduction mechanism in monovalent and multivalent ions doped polyaniline

Gupta

Luthra²,

Singh

2012

Bull Mater Sci

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A detailed comparative study of electron paramagnetic resonance (EPR) in conjunction with d.c. electrical conductivity has been undertaken to know about the charge transport mechanism in polyaniline (PANI) doped with monovalent and multivalent protonic acids. This work is in continuation of our previous work for further understanding the conduction mechanism in conducting polymers. The results reveal that the polarons and bipolarons are the main charge carriers formed during doping process and these cause increase in electrical conductivity not only by increase in their concentration but also because of their enhanced mobility due to increased inter-chain transport in polyaniline at high doping levels. EPR line asymmetry having Dysonian line shape for highly doped samples shows a marked deviation of amplitudes A/B ratio from values close to one to much high values as usually observed in metals, thereby support the idea of high conductivity at higher doping levels. The nature of dopant ions and their doping levels control the charge carriers concentration as well as electrical conductivity of polyaniline. The electrical conductivity has also been studied as a function of temperature to know the thermally assisted transport process of these charge carriers at different doping levels which has been found to follow the Mott's variable range hopping (VRH) conduction model for all the three dopants used. The charge carriers show a change over from 3D VRH to quasi 1D VRH hopping process for multivalent ions at higher doping levels whereas 1D VRH has been followed by monovalent ion for full doping range. These studies collectively give evidence of inter-chain percolation at higher doping levels causing increase in effective mobility of the charge carriers which mainly seems to govern the electrical conduction behaviour in this system.

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Section: Resultssupporting

confidence: 68%

Electrical transport and EPR investigations: A comparative study for d.c. conduction mechanism in monovalent and multivalent ions doped polyaniline

Gupta

Luthra²,

Singh

2012

Bull Mater Sci

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“…This type of line shape is characteristic for highly doped polymers and indicates an increased interaction of charge carriers within the skin with microwave field [54]. Thus, the increase in the A/B ratio is not only a further evidence for the copolymer formation but also indicates the enhancement of conductivity [55]. This result is also consistent with the room temperature conductivity measurements.…”

Section: Structure and Morphology Analysis Of Poly(i-co-ani)supporting

confidence: 85%

Electrochemical copolymerization and characterization of dianilines linked by polyether bridge with aniline

Tirkeş

Önal

2010

J Appl Electrochem

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Copolymer of aniline and triethylene glycol bis(o-aminophenyl) ether was synthesized by constant potential electrolysis. Cyclic voltammogram of the copolymer films recorded in the monomer-free electrolytic solution revealed that the redox behavior of the films approaches to that of poly(triethylene glycol bis(o-aminophenyl) ether) with increasing amount of triethylene glycol bis(o-aminophenyl) in the feed ratio. Copolymerization was investigated by in situ recording the changes in the electronic absorption spectrum during electrolysis. The free standing copolymer film was characterized utilizing Fourier transform infrared spectrometer, and spectroelectrochemical behavior of the copolymer was investigated via in situ UV-vis spectroscopic technique. Besides the electron spin resonance study of the copolymer film, the different morphologies of the polymers were examined by scanning electron microscopy and the copolymerization was confirmed. The temperature dependence conductivity of the copolymer film was measured by four-probe technique in the temperature range of 100-300 K, and the calculated parameters showed that conduction mechanism fits to variable range hopping.

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“…This result was determined from IR and electronic spectroscopy measurements [3], but no attempt to detect ion radicals of the oligomers by EPR spectroscopy was reported. However, there are a few reports of solid oxidized tetraaniline [4,5] (I, n = 4, oxidized to emeraldine base structure [EB]) and several of the EPR spectra of PANI [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Magnetic resonance studies of aniline oligomers formed in the reaction of aniline with 1,1-diphenyl-2-picrylhydrazyl

et al. 2005

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Aniline oligomers, which are formed in the reaction of aniline with 1,1-diphenyl-2-picrylhydrazyl (DPPH) in methanol and chloroform as solvents, are investigated by means of magnetic resonance techniques. The electron paramagnetic resonance (EPR) spectrum of the products of the reaction of aniline with DPPH (mole ratio, 2:1) in chloroform solution, and of aniline with DPPH (mole ratio, 1:2) in methanol solution, were recorded as the reaction progressed, and after the reaction was finished. The spectra of the products after reaction were resolved into the spectra of two species. For the acidified methanol solution the spectrum of one of the species shows hyperfine coupling to two nitrogen atoms with a coupling constant a(2-t4N) = 5.8 G, in good agreement with previously reported observations for the radical cation of model aniline trimers. A species is observed in the chloroform solution with a(1. t4N)= 11.4 G, which suggests the presence of aniline dimers. Both solutions also show a second signal which is attributed to higher oligomer radical cations with unresolved t4N hyperfine structure, tH nuclear magnetic resonance (NMR) spectra of aniline and aniline-DPPH solutions in CDCI 3 with the peaks due to DPPHH, the product of reduction of DPPH, were observe& The ~H NMR experiments show that only 15% of the available aniline was consumed, in agreement with the theoretical calculations for the formation of polyaniline-emeraldine base salt under these conditions rather than the sole formation of dimers, which would be expected to consume 33% of the available aniline. This is probably due to formation of partially oxidized long-chain aniline oligomers as the main reaction product.

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EPR and electrical conductivity in microporous polyaniline

Cited by 29 publications

References 9 publications

Electrical transport and EPR investigations: A comparative study for d.c. conduction mechanism in monovalent and multivalent ions doped polyaniline

Electrical transport and EPR investigations: A comparative study for d.c. conduction mechanism in monovalent and multivalent ions doped polyaniline

Electrochemical copolymerization and characterization of dianilines linked by polyether bridge with aniline

Magnetic resonance studies of aniline oligomers formed in the reaction of aniline with 1,1-diphenyl-2-picrylhydrazyl

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