Polyacetylene chemical doping

Billaud et al. [99] have also recently proposed a distorted hexagonal structure (actually monoclinic) for highly oriented polyacetylene chemically doped with lithium to y = 0.16. 

Fig. 1. (a) Comparison of normalised electrical conductivity of individual MWCNTs (Langer 96 [17], Ebbesen [18]) and bundles of MWCNTs (Langer 94 [19], Song [20]). (b) Temperature dependence of resistivity of different forms (ropes and mats) of SWCNTs [21], and chemically doped conducting polymers, PAc (FeClj-doped polyacetylene [22]) and PAni (camphor sulfonic acid-doped polyaniline [2. ]) [24]. 

Although it was initially believed that polyacetylene was unstable in contact with water under all conditions, it has been successfully chemically doped in aqueous solutions with no apparent degradation of the material [82] and its electrochemistry has also been investigated [135-137] from which it is clear that no degradation occurs in concentrated aqueous electrolytes. Reaction with water can occur under some circumstances however giving rise to sp3 carbons and carbonyl-type structures [129, 138-141],... 

The synthesis and characterization of polyacetylene (PA) provided new incentive for understanding 7r-electronic spectra, electron-phonon interactions and electronic correlations[l, 2, 14]. The electrical conductivity of chemically doped PA rivals that of metals. Families in Fig. 2 such as polydiacetylenes (PDAs), poly thiophenes (PTs), cr-conjugated polysilane (PSs) and polyparaphenylene vinylene (PPVs), among... 

Akagi, K. Kadokura, T. Shirakawa, H. Stereospecific chlorination of polyacetylene by chemical doping. Polymer 1992, 55(19), 4058-4065. 

It has been first demonstrated in 1977 by MacDiarmid et that films of polyacetylene can be chemically doped to semiconducting and metallic states. Shortly thereafter the possibility of electrochemical doping, resulting in highly conducting materials, had been shown not only for polyacetylene but also for a number of other polyenes, polyphenylenes and polychalcogenides. ... 

A recent study related to the current topic concerns the chlorination of polyacetylene, and addresses a new aspect of chemical doping. Akagi et al. [157] show that iodine doping of stretched polyacetylene films followed by chlorination produces stereoregularly chlorinated... 

Figure 4.14. Mossbauer spectrum of polyacetylene electro-chemically doped with FeCl4". (Reproduced Irom Mai Res. Bull. 17, 1505 (1982), A. Pron, el al. Copyright 1982, with kind permission from Elsevier Science Ltd, Kidlington 0X5 1GB, UK.)...

Organic Materials are new in this field of application. Polyacetylene, (CH), may be chemically doped either p- or n-type and electric conductivity can be... 

Table 1. Conductivity and giavimetiy data for n-doped polyacetylenes chemically synthesized in metal-ammonia solutions. 

Polyacetylene is most commonly obtained by the Shirakawa method in which acetylene gas is polymerized by using a Ziegler-Natta catalyst [10,11]. Many studies have been conducted on the chemical doping of polyacetylene [12-16]. It is also one of the most widely studied conductive polymers with respect to its electrochemical properties. 

Polyacetylene, a one-dimensional, conjugated polymer represented as (CH) exhibits electrical conduction upon chemical doping with an electron acceptor or donor [1,2]. The chemical doping transforms the polyacetylene from insulator or semiconductor to conductor. Ordinary polyacetylene film is composed of fibrils that are bundles of polyene chains. Because the fibrils are randomly oriented, the inherent electrical conductivity of the polyacetylene chain is depressed owing to fibril contact resistance. This makes it difficult for polyacetylene to become a complete one-dimensional conductor at the macroscopic level. Today, the primary concern is how to align the fibrils of polyacetylene film in order to achieve higher electrical conductivity. 

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