Polyacetylene highly conducting

Polyacetylene is considered to be the prototypical low band-gap polymer, but its potential uses in device applications have been hampered by its sensitivity to both oxygen and moisture in its pristine and doped states. Poly(thienylene vinylene) 2 has been extensively studied because it shares many of the useful attributes of polyacetylene but shows considerably improved environmental stability. The low band gap of PTV and its derivatives lends itself to potential applications in both its pristine and highly conductive doped state. Furthermore, the vinylene spacers between thiophene units allow substitution on the thiophene ring without disrupting the conjugation along the polymer backbone. 

Polymer Batteries The discovery that doping of polyacetylene produced a highly conducting material was followed swiftly by the realization that this material was a rechargeable battery material which, optimistically, might lead to lightweight... 

All commodity polymers (that is those manufactured and sold in high volume) act as insulators because they have no free electrons to conduct electricity. Some low-volume polymers, such as polyacetylene, are conductive or semi-conductive, but their applications are specialized and their use limited. In this section, we shall concentrate on the properties of commodity polymers, because these materials represent the vast majority of polymers used in electrical applications. 

These quarternized polymers can be viewed as self-doped but exhibit relatively low intrinsic conductivities. The polymers can be oxidatively doped with iodine, or reductively doped with TTF, to give highly conducting polyacetylenes with conductivities of 10"4 and 10 1 S/cm, respectively. One additional attractive feature of this system is that, unlike PA, these quarternized PAs are very stable in air. 

Though conductivity of polyaniline is not as high as that of some other polymers, it is emerging as the material of choice for many applications. It is stable in air and its electronic properties can be easily tailored. It is one of the oldest synthetic polymers, and probably it is the cheapest conducting polymer used in devices. It can be easily fabricated as thin films or patterned surfaces. Polyaniline will never replace the materials which have extremely high conductivity. However, it will be useful for certain specific applications. Andy Monkman has a program to extrude the polymer braids and lay the insulation of the coaxial cables in a single step. The work is supported by a cable company [3], Properties of polyacetylene are discussed in detail in Chapter 2. 

Nevertheless, there are cases in which conductivity is not governed by disorder, or at least in a less drastic way. This is the case of highly conducting polyacetylene [27]. Conductivity approaching the value of copper at room temperature has been reported, and a high value is still observed at low temperature. Recently, polyaniline with camphor sulfonic add (CSA) as the counterion has been reported to present an almost flat temperature dependence of conductivity [28]. Such examples are quite rare, but they are of major importance for an understanding of the intrinsic conduction process. 

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