Conjugated polymers doped

An outline of a quantitative description of the dispersion phenomenon is given below. This theory provides a description of the backbone structure of a polymer insofar as it evaluates a distribution function for conjugation lengths on the chains. In certain cases this was found to correlate with the conductivity of the polymer after doping and thus provided important information concerning the conduction mechanism. Fig. 4.8-5b... 

Properties of representative conducting polymers. Doped conjugated polymers have generated substantial interest in view of possible applications such as lightweight batteries, antistatic equipment, and microelectronics to speculative concepts such as molecular electronic devices.37-38 These polymers include doped polyacetylene, polyaniline, polypyrrole, and other polyheterocycles (Figure 5). While the conduction mechanism of metals and inorganic semiconductors is well understood and utilized in microelectronics, this is not true to the same... 

Conductive polymers have been a goal of fundamental polymer research for many years, mainly because such materials would be lightweight and presumably moldable into any shape desired. Ten years ago, almost every polymer known displayed insulator properties, and research efforts to modify their character met with failure. Since that time, however, success has been reported in the literature, and a few conductive polymers do exist now, each with its merits and drawbacks. Various degrees of conductivity can be achieved principally by synthesizing an unsaturated, conjugated polymer and doping it in some fashion. Example polymers are polyphenylene,... 

It was recently shown that doping poly(pPIN) with iodine produces a semi-conductive material, with conductivities of about 8 X 10 S cm typical of non-conjugated doped polymers [99]. This material also showed a large quadratic electro-optic effect which would make it useful for non-linear optics applications [100]. 

Shortly after discovery of methods for preparation of organic soluble derivatives of poly(phenylene vinylene) and polythiophene, Wudl and coworkers reported preparation of each of these polymers with sulfonated side groups. The specific objective of this work was based on the idea that the anionic sulfonate groups could make the polymers self-doping , wherein the covalently linked anionic units could serve to provide charge compensation when the polymer backbone is in the oxidized (semiconducting) state. These first studies focused on the synthetic monomer and polymer chemistry. However, the authors reported in their papers that their newly synthesized conjugated... 

Thin polymeric films of the parent thiophene are blue (Xmax = 730 nm) in the doped (oxidized) state and red (A.max = 470 nm) in the imdoped form. However, because of its lower oxidation potential, the electropolymerization of 3-methyl thiophene has been more intensively studied than the parent thiophene. Furthermore, the introduction of a methyl group at the )8-position of the thiophene ring leads to a significant increase of the polymer conjugation length and hence electronic conductivity (55). This effect has been attributed to the statistical decrease in the number of a-fl couplings and to the decrease of the oxidation potential caused by the inductive effect of the methyl group (55). Poly(3-methylthiophene) is purple when neutral and turns pale blue on oxidation. 

Corresponding to the electrochemical oxydation of the aromatic hydrocarbons the chemic or electrochemical oxydation or reduction of conjugated polymers - called "doping -occurs. 

Table I. Electrical Conductivities of Various rr-Conjugated Polymers in Doped State...

Graph 1. Comparison of conductivities between inorganic materials and various conjugated polymers (d = doped). 

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