High‐Field ESR Spectroscopy of Conductive Polymers

Krinichnyi, V.I.

doi:10.1002/047005350x.ch12

Cited by 11 publications

(12 citation statements)

References 36 publications

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“…The hexylTTXTT polymer signals saturated only around 20 K and below whereas measurements for related polymers were taken between 90 and 293 K. Unfortunately, low spin concentrations of <10 16 spins/m 3 (Table ) likely restricted the measurements to such low temperatures as doped organic conducting polymers generally contain 10 22 –10 27 spins/m 3 . At 90 K, doped poly(3-octylthiophene) has a T 2 of about 5 × 10 –7 s, similar to our values at much lower temperatures . However, the T 1 is considerably slower at about 1 × 10 –4 s .…”

Section: Resultssupporting

confidence: 74%

“…The inter- (1D) and intrachain (3D) conductivity of the polymers with temperature were determined using the following equations: where N s is the number of spins, e is the elementary charge, k B is the Boltzmann constant, T is temperature, c 1D and c 3D are the intra- or interchain lattice constant, respectively (Table ). The calculated conductivities are likely rough estimates as we used the X-ray scattering lattice constants of c 1D = 0.785 nm and c 3D = 0.480 nm reported for oriented poly(3-octylthiophene) and due to the previously mentioned difficulties with spin counting.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, at higher fields a more complete picture of the structure, relaxation, and molecular dynamics of conducting polymers can be obtained. An increase in sensitivity to the anisotropy of molecular rotation is also seen when Q-band (35 GHz) EPR is used, but at this frequency the anisotropy of the resonant field of the radical centers is comparable with the anisotropy of superfine interaction, leading to difficulties in spectral interpretation and modeling …”

Section: Introductionmentioning

confidence: 99%

“…An increase in sensitivity to the anisotropy of molecular rotation is also seen when Q-band (35 GHz) EPR is used, but at this frequency the anisotropy of the resonant field of the radical centers is comparable with the anisotropy of superfine interaction, leading to difficulties in spectral interpretation and modeling. 16 Although a wealth of information can be obtained with HF ST-EPR, the method is not commonly used. In the biochemical field, Fajer and co-workers used HF ST-EPR to study the rotational molecular motion of several spin labeled proteins, demonstrating the method's utility in the study of chemical biology problems.…”

Section: ■ Introductionmentioning

confidence: 99%

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Chain Dynamics, Relaxation Times, and Conductivities of Bithiophene–Acene Copolymers Measured Using High Frequency Saturation Transfer EPR

Fraind¹,

Ryzhkov

Tovar³

2016

J. Phys. Chem. B

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We present a study to probe the formation of localized aromatic sextets and their effects on the charge transport properties in polymers with acene cores. Bithiophene-acene copolymers containing benzene, naphthalene, or anthracene as acene cores were synthesized using Yamamoto polymerization. Drop-casted polymer films were chemically doped and analyzed using high frequency saturation transfer EPR (HF ST-EPR), a method which has proven useful in the study of conducting polymers. The spin-spin and spin-lattice relaxation times were determined for these polymers at low temperatures (4 to 20 K) and used to obtain inter- and intrachain spin diffusion rates and conductivities. Similar interchain spin diffusion rates were seen across all polymer systems; however, anthracene containing polymer poly(hexylTTATT) was found to have the largest intrachain spin diffusion rate. The poly(hexylTTATT) intrachain spin diffusion rate may be artificially high if the anthracene ring restricts the diffusion of spin to the hexylated quaterthiophene segment in poly(hexylTTATT) whereas the spins diffuse through the acene cores in the benzene and naphthalene derivatives. Alternatively, as both the spin diffusion rates and conductivities vary unpredictably with temperature, it is possible that the π-electron localization previously seen in the anthracene core could be relieved at lower temperatures.

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Section: Resultssupporting

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Chain Dynamics, Relaxation Times, and Conductivities of Bithiophene–Acene Copolymers Measured Using High Frequency Saturation Transfer EPR

Fraind¹,

Ryzhkov

Tovar³

2016

J. Phys. Chem. B

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“…As such 2D-CPs should be of great interest for room temperature studies of anomalous integer Quantum Hall effect and other quantum electrodynamics phenomena 2,25 . At the same time these Fermi velocities remain comparable to those of conventional doped 1D-conjugated polymers such as Polymeric Tetrathiafulvalenes (PTTF) 26,27 . They have the additional advantages of ballistic carriers and an extended 2D network rather than hopping between finite 1D chains.…”

mentioning

confidence: 59%

Dirac Cones in two-dimensional conjugated polymer networks

et al. 2014

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Linear electronic band dispersion and the associated Dirac physics has to date been limited to special-case materials, notably graphene and the surfaces of three-dimensional (3D) topological insulators. Here we report that it is possible to create two-dimensional fully conjugated polymer networks with corresponding conical valence and conduction bands and linear energy dispersion at the Fermi level. This is possible for a wide range of polymer types and connectors, resulting in a versatile new family of experimentally realisable materials with unique tuneable electronic properties. We demonstrate their stability on substrates and possibilities for doping and Dirac cone distortion. Notably, the cones can be maintained in 3D-layered crystals. Resembling covalent organic frameworks, these materials represent a potentially exciting new field combining the unique Dirac physics of graphene with the structural flexibility and design opportunities of organic-conjugated polymer chemistry.

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Polymer Characterization: Electron Paramagnetic Resonance

Krinichnyi

2018

Encyclopedia of Polymer Science and Technology

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Advantages of multifrequency electron paramagnetic resonance spectroscopy combined with various methods—such as spin labels and probes, microwave saturation, and saturation transfer—for investigating various polymeric systems are presented. Paramagnetic centers that are stabilized and/or initiated as a nanoscope probe can provide detailed information about structure and dynamics of the microenvironment. Correlations of structural, morphological, and dynamic characteristics of polymer systems with magnetic, relaxation, and mobile properties of paramagnetic centers embedded into their bulk are also discussed.

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High‐Field ESR Spectroscopy of Conductive Polymers

Cited by 11 publications

References 36 publications

Chain Dynamics, Relaxation Times, and Conductivities of Bithiophene–Acene Copolymers Measured Using High Frequency Saturation Transfer EPR

Chain Dynamics, Relaxation Times, and Conductivities of Bithiophene–Acene Copolymers Measured Using High Frequency Saturation Transfer EPR

Dirac Cones in two-dimensional conjugated polymer networks

Polymer Characterization: Electron Paramagnetic Resonance

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