Infrared Spectra of Poly(acetylene)

Shirakawa, Hideki; Ikeda, Sakuji

doi:10.1295/polymj.2.231

Cited by 747 publications

(219 citation statements)

References 15 publications

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“…as determined by its absorption intensities 20 . For trans-(CH)x, the samples were immediately isomerized by heating at 2001C for 2 hours in vacuo.…”

Section: Methodsmentioning

confidence: 99%

Electron paramagnetic resonance saturation characteristics of pristine and doped polyacetylenes

Chien¹,

Wnek²,

Karasz³

et al. 1982

Macromolecules

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Electron paramagnetic resonance saturation experiments have been carried out on undoped polyacetylene and on the doped polymer as a function of dopant concentration. The relaxation times of undoped trans-(CH)x show considerable variability from sample to sample, Tr = (2.7 ± 1.7) X 10"5 s and T2 = (7.8 ± 1.0) X 10~8 s, suggesting sensitivity to trace impurities. Exposure to air reduces Tx to 8.1 X 10"6 s and T2 to 6.6 X 10"8 s; this effect is reversible. The use of radioassay techniques with 125I made it possible to prepare and characterize samples of known dopant concentration at the level of parts per million (ppm). There are three distinct regimes which characterize the effect of iodine concentration on the EPR characteristics of trans-(CHly)x. In the region 3 X 10"6 < y < 10"3, T1 decreases with increasing y, while T2 is unaffected. The neutral soliton concentration, [S•], remains constant in this region. Dilute doping results in conversion of S• to a spinless positive soliton S+ and/or direct oxidation of (CH)X to create S+S+ pairs. In the intermediate concentration regime, 10~3 < y < 10"2, both 7\ and T2 decrease with y, and [S•] decreases as y"3•7, suggesting that the dopant is predominantly in the material as I3" with the remainder as I5". When y exceeds 1CT3, there Eire one or more dopant molecules per (CH)X chain and the number of neutral solitons is significantly reduced.In the heavily doped samples, the EPR has a Dysonian line shape until it vanishes for y > 2 X 10~2. The observation of changes in relaxation times even at the dopant level of ppm implies that the dopant ions are randomly distributed throughout the polymer and that the solitons are highly mobile. On the other hand, for cis-(CH)x, doping with iodine from y = 3.3 X 10~5 to 3.9 X 10"4 does not significantly affect 7\ or T2, for pristine cis-(CH)x, Tl = (5.4 ± 0.9) X 10"5 s and T2 = (1.0 ± 0.07) X 10"8 s. Therefore, the solitons in cis-(CH)Z have low diffusivity. Very slowly doped trans-[CH(AsF6);y]x also displays three characteristic regions. In the dilute regime, Tb T2, [S•], and the AZ/pp dependence on Hx are not significantly different from those of pristine trans-(CH)x. Above y > 6 X 10"3, [S-] first decreases with y and then the EPR intensity increases rapidly as the Pauli susceptibility makes its contribution. In the transitional regime, 6 X 10"3 < y < 5 X 10"2, the resonance could not be saturated with the power available, implying Einomalously short rekixation times (Tf), whereas saturation was again possible in the heavily doped metallic limit.

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“…as determined by its absorption intensities 20 . For trans-(CH)x, the samples were immediately isomerized by heating at 2001C for 2 hours in vacuo.…”

Section: Methodsmentioning

confidence: 99%

Electron paramagnetic resonance saturation characteristics of pristine and doped polyacetylenes

Chien¹,

Wnek²,

Karasz³

et al. 1982

Macromolecules

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“…1 ra vacuum line pretreated with AsF 5 , elemental analyses for C, K, As'and F give "an arsenic to fluorine ratio of 1:5 (Table I).17,I1…”

Section: Doping Of (Cr) Filmsmentioning

confidence: 99%

“…' Dark red gels of toluene in (01)"'may be prepared using a lower catalyst concentration. 1 Hhl porous, veryx'low density* "foam-.like" (CH! )/I can be obtained from these gels.…”

mentioning

confidence: 99%

Semiconducting and Metallic Covalent Polymers: (CH)X and its Derivatives

MacDiarmid¹,

Heeger²

1980

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“…[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. The electronic conductivity in conjugated polymers is due to the ease of electronic jumps between chains.…”

Section: Introductionmentioning

confidence: 99%

Artificial muscles based on conducting polymers

Cortés

Moreno

2003

E-Polymers

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Natural muscles have mechanical properties that conventional actuators do not possess. These natural machines show large strain, moderate stress, high efficiency and stability, fast response time, high power/weight ratio, long lifetime, etc. In the last years a great interest has arisen to develop materials that mimic natural mechanisms. Conducting polymers have an array of potential applications as artificial muscles since they are capable to produce a moderate displacement when submitted to an electrochemical reaction. This property has been used to fabricate actuator devices that imitate and even improve the performance of natural muscles. For example, conducting polymers show stresses 15 times higher than those generated by mammalian muscles, a high power/weight ratio and a high degree of compliance. However, there are also several responses that need improvement in the actuators based on conducting polymers. Strains are still c. 50% lower than in natural muscles. Most of this kind of actuators only work in liquid media. It is necessary to increase the response time and obtain more durable actuators with longer lifetime and higher stability. In spite of these disadvantages, the first actuators based on conducting polymers are being commercialized. This paper presents a brief summary of some of the actuators based on these polymers, focusing on their design, performance and actuation mechanism.

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Infrared Spectra of Poly(acetylene)

Cited by 747 publications

References 15 publications

Electron paramagnetic resonance saturation characteristics of pristine and doped polyacetylenes

Electron paramagnetic resonance saturation characteristics of pristine and doped polyacetylenes

Semiconducting and Metallic Covalent Polymers: (CH)X and its Derivatives

Artificial muscles based on conducting polymers

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