3.4- ethylenedioxythiophene polythiophenes based

Early progress in polythiophene chemistry was achieved by the synthesis of mono- and dialkoxy-substituted thiophene derivatives developed by Leclerc [6] and industrial scientists at Hoechst AG [7-9]. However, most polymers of mono- and dialkoxythiophenes exhibited low conductivity in the oxidized, doped state. A breakthrough in this area was the synthesis of polymers of the bicyclic 3,4-ethylenedioxythiophene (EDT or EDOT) and its derivatives—electrochemically polymerized by Heinze et al. and chemically polymerized by Jonas et al. of the Bayer Corporate Research Laboratories [10,11]. In contrast to the nonbicyclic polymers of mono- and dialkoxythiophenes, PEDT has a very stable and highly conductive cationic doped state. The low HOMO-LUMO bandgap of conductive PEDT allowed the formation of a tremendously stable, highly conductive ICP [12]. Technical use and commercialization quickly followed today ICPs based on PEDT are commercially available in multiton quantities. 

One class of polythiophene derivative has been studied for use in Type I supercapacitors research into poly(3,4-ethylenedioxythiophene) (PEDOT, Figure 9.4J)-based supercapacitors has been driven by PEDOT s superior chemical and electrochemical stability [148] as well as its fast switching times [161]. Carlberg and Inganas [148] demonstrated energy density of 1 Wh/kg at power densities of... 

Poly (thiophene)s are of particular interest as electfochromic materials owing to their chemical stability, ease of synthesis and processability. For the most part, current research has been focused on composites, blends and copolymer formations of several conjugated polyheterocyclics, polythiophene and its derivatives, especially PEIX)T. In one example, poly(3,4-ethylenedioxythiophene) (PEDOT)/poly(2-acrylamido-2-methyl-l-propanesulfonate) (PAMPS) composite films were prepared by Sonmez et al. for alternative electrochromic applications [50]. Thin composite films comprised of PEDOT/PAMPS were reported to switch rapidly between oxidized and neufial states, in less than 0.4 s, with an initial optical contrast of 76% at A.max. 615 nm. Nanostructured blends of electrochromic polymers such as polypyrrole and poly(3,4-ethylenedioxythiophene) were developed via self-assembly by Inganas etal. for application as an electrochromic window [26]. Uniir etal. developed a graft-type electrochromic copolymer of polythiophene and polytetrahydrofuran for use in elecfiochromic devices [51]. Two EDOT-based copolymers, poly[(3,4-ethylenedioxythiophene)-aZ/-(2,5-dioctyloxyphenylene)] and poly[(3,4-ethylenedioxythiophene)-aft-(9,9 -dioctylfluorene)] were developed by Aubert et al. as other candidates for electrochromic device development [52],... 

Nanofibers of conducting polymers such as those spun from polyaniline (PANi) are particularly well suited for use in conductivity sensors. Polymers commonly explored in sensor research include PANi, polythiophene (PT), poly(3,4-ethylenedioxythiophene) (PEDOT), and polypyrrol (PPy), sometimes with other constituents, to enhance their sensing capability. Some of these such as PANi (Norris et al. 2000 Zhu et al. 2006a) and PPy (Kang et al. 2005 Nair et al. 2005) (as well as their hlends), can be readily electrospun into nanofibers. Polyaniline is somewhat unique in that its doped state can be controlled by the pH of the medium, allowing it to exist either as the emaraldine base or as the salt (Scheme 8.1). Simple acids and... 

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