Doping with FeCl

For Tsukamoto polyacetylene doped with FeCls, Ishiguro et al. [138] report a more compact structure than found before for Akagi polyacetylene. The authors specify a rectangular, face-centred projected chain array, 17.4 A, 6 = 9.8 A L =L =36 A. 

SbCls results in an electric conductivity of 0.18 S cm, while doping with FeCls leads to a conductivity of 0.8 Scm. ... 

The polymer is stable at temperatures up to 380 °C. Optically clear, self-supporting layers having a modulus of elasticity of 1.3 GPa can be prepared from a solution. Layers of the polymer adhere very well to metals, in particular to gold. By means of oxidation agents, PPSA can be doped to form ap-type material. Doping of a self-supporting layer of PPSA with SbCls results in an electric conductivity of 0.18 S cm , while doping with FeCls leads to a conductivity of 0.8 S cm ... 

In poly(5-vinyl-2,2 5, 2"-terthiophene), in which terthiophene is a side group of a carbon-carbon chain polymer, the terthiophene side chains cross-link when the polymer is doped with FeCls or SbCls in solution or as thin film. The terthiophene radical cations, initially generated upon doping, couple with neighboring neutral species to yield the radical cations of sexithiophene. The dedoping of the polymer with triethylamine yields an insoluble, cross-linked material [242]. 

R. Mertens, P. Nagels, R. Callaerts, J. Briers, and H. J. Geise, Electrical conductivity of poly(para-phenylene vinylene) films doped with FeCL, Synth. Met. 55-57 3538 (1993). 

Fig. 28.14 Raman spectra of doped PA. (a) Pristine, Aexc = 458 nm (b) 2% doped with iodine, Aexc = 458 nm (c) 1% doped with CIO4, Aexc = 458 nm (d) highly doped with Li, Aexc = 458 nm (e) 13% doped with FeCl, Aexc = 413 nm. (From Ref. 142.)...

Alkylated PT films (with decyl substitution) have an electrical conductivity of up to 5Scm" [26] 3,4-dibutoxyPT doped with FeCls reaches only IS cm" [27-30]. Other 3-alkylated PT materials (octyl, decyl) doped with FeCl3 are claimed to be stable for 10 to 100 years (by extrapolation ) [31-32]. 

Scheme 33 shows the reaction of polymer 127 with an excess of iron pen-tacarbonyl under UV irradiation to produce the iron tricarbonyl-coordinated polymer 1287 NMR spectroscopy was used to determine that the ratio of coordinated to non-coordinated silole rings was 2 1. Conductivity measurements were performed on polymers 127 and 128 doped with FeCls. It was found that doped 127 had a conductivity of 10 S/cm, while the conductivity of doped 128 had a conductivity of 10 S/cm. X-ray crystallography studies of model compounds indicated that Fe(CO)3-coordinated silole rings have enhanced n conjugation. 

Olmedo et al. [486] described another typical template-type in-situ chemical polymerization of P(ANi) and poly(alkyl-thiophenes) on many textile fabrics, with various dopants, but using K2Cr207 as oxidant. Real and imaginary permittivities for poly(3-octyl/butyl thiophenes) doped with FeCl/ lay respectively in the 7 to 30 and 2 to 80 ranges. 

Figure 8.14. Absorption spectra of P30T (dash line) and P30T doped with FeCls (dot-dash line). The difference spectrum is shown on the right-hand axis (solid line). (Reproduced by permission of The American Physical Society from ref. 54.)...

Polymeric tubes for clad lead-acid battery plates have been made from intrinsically conductive polymers [19] by weaving fibres of polypyrrole, poly(phenylene vinylene), or polythiophene of several hundred microns in thickness. Polyaniline [20] as well as polypyrrole, polyparaphenylene, and polyacetylene doped with anions (C104, FeCl, AsFj, sol", and HSO4) have also been added as 1.15pm powders or fibres to positive pastes to improve capacity [21]. 

The general reaction describing chemical doping of conjugated polymers with FeCls can be expressed as follows ... 

However, when Pani samples are doped with SnCU or FeCls somewhat different results are obtained. SnCU-doped samples exhibit an absorption band at 370 nm, and a broad absorption band with maximum at 1530 nm. On the other hand, FeCla-doped samples exhibits an extremely broad absorption band extending toward NIR with a maximum around 1700nm. This is evidence of the influence of the Lewis acid on the UV-Vis/NIR (near-infrared) spectra of Lewis acid-doped polyaniline. In the present case, the UV—Vis spectra for the oxide—Pani samples resemble those obtained for Pani doped with Hthium salts. 

In addition to the various dithienothiophene polymers, the related thieno[3,4-h] thiophene (1) and its derivatives have received considerable attention. The first reported example was the alkyl-functionalized derivative, poly(2-decylthieno[3,4-h]thiophene) (73) reported by Pomerantz and Gu [109]. Polymer 73 was prepared by the FeCls oxidation of 2-decylthieno[3,4-l jthiophene, which was synthesized from 2-thiophenecarboxylic acid as illustrated in Scheme 12.16 [109,110]. Such methods produced a fairly high LLk material LLk = 90,000, M = 52,000, PDI =1.7) that was blue-green in color and soluble in a variety of organic solvents (CHCI3, THF, and chlorobenzene). Solvent cast films exhibited a transition at 925 nm with an onset at 1350 nm (F of 0.92 eV). FeCls-doped films gave a conductivity of 3.1 X 10 . Films doped with either I2 or NOBF4 gave lower conductivities (1.0—4.2 x 10 ). 

Doping by FeCls was found to be particularly interesting. When PPP was treated with FeCls dissolved in dry NM, the conductivity of PPP increased at about 0.31 S cm and Mossbauer spectroscopy showed that Fe was completely reduced to Fe [226]. 

The solid-state doping of 6T with FeCls leads to polaron formation up to a dopant level of one effective charge per 6T, and at higher dopant concentrations polaron bands rather than bipolarons are formed [181,182]. The formation of polarons and of bipolarons at higher doping levels are also observed in POT [183]. 

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