Condensed conducting polymer

The science and technology of conducting polymers are inherently interdisciplinary they fall at the intersection of three established disciplines chemistry, physics and engineering hence the name for this volume. These macromolccular materials are synthesized by the methods of organic chemistry. Their electronic structure and electronic properties fall within the domain of condensed matter physics. Efficient processing of conjugated polymer materials into useful forms and the fabrication of electronic and opto-electronic devices require input from engineering i. e. materials science (more specifically, polymer science) and device physics. 

In contrast to the interfacial oxidative condensation polymerization, where discharge of anions occurs at the growing end through the conductive polymer, a new cathodic process of formation of unstable monomers has been developed, followed by polymerization. 

In 1961, Gewald and co-workers published the synthesis of poly-substituted thiophenes involving condensation of cyanoacetate and elemental sulphur with ketones or aldehydes in a three-component reaction (Scheme 5.9). Beyond their industrial use in dyes and conducting polymers, 2,5-substituted thiophenes have shown extensive potential in the pharmaceutical industry. Most published Gewald thiophene synthetic procedures require reaction times between 8 and 48 h for the condensation step. Hoener and... 

Although the methods reviewed above have been most widely used for synthesis of conducting polymers, there are many other organic reactions capable of producing conjugated structures. One example is the Wittig condensation of bis-triphenyl-phosphonium compounds with dialdehydes in the presence of a strong base, typified by the synthesis of poly(p-phenylene-vinylene) 102). 

The use of the high internal area of electronically conducting polymers should make such materials good (cheap) electrochemical capacitors (see Section 13.19) where there would be much to gain (economically ) over, say, porous Ru02. In condenser discharge, no net current flows so that ohmic losses in pores are not relevant. 

High quantum yield photochemical reactions of condensed-phase species may become useful for future optical applications such as molecular switches, optical limiters, and read-write data storage media. Toward these ends, much research has been conducted on novel nonlinear chemical-based materials such as conducting polymers and metal-organic species. Monitoring the early time-dependent processes of these photochemical reactions is key to understanding the fundamental mechanisms and rates that control the outcome of these reactions, and this could lead to improved speed and efficiencies of devices. 

In this paper we report on the synthesis of new types of intrinsically conducting polymers using high-temperature reaction of condensation polymers and polyfunctional monomers. We shall show that the new polymers can be regarded as low-dimensional graphites both macroscopically and microscopically and discuss the change in their structural and electronic properties with heat-treatment temperature (HTT). 

The formation of -aminodiphenylamine is supposed to be the key intermediate in the formation of a dark green precipitate at the electrode surface during continued electrolysis of acidic aniline solutions. This has been characterized as an oligomer of aniline, for example, as the octamer emeraldine formed by a cascade of head-to-tail condensations [38,39]. Nelson, however, explained it as a mixture of mainly quinhydrone with a small amount of benzidine salt [37]. Today the electropolymerization of aniline under strongly acidic conditions is intensively studied as an important way to form the conducting polymer polyaniline [40] (see Chapters 31 and 32). 

Organic polymers that possess the electronic, magnetic, and optical properties of metals are known as conductive polymers (CPs). Because of their conjugated u electron backbones, they can be oxidized or reduced more easily and more reversibly than conventional polymers with charge-transfer agents, also commonly called dopants, a term borrowed from condensed matter physics. While retaining some of the mechanical properties of polymers, they do not melt or dissolve in common organic solvents, a major impediment to their widespread commercialization in the same manner as traditional plastics. The same electronic structure that confers electrical conductivity to these polymers also contributes to their intractability and instability. 

Ohmura, K. Kijima, M. Shirakawa, H. Synthesis of conducting polymers with conjugated carbon-carbon triple bonds by electrochemical condensation of acetylene derivatives catalyzed by copper complex. Synth. Metals 1997, 84, 417-418. 

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