Conducting polymer containing synthetic

The coupling reaction of organic-zinc compounds and organic bromides was also used to prepare a conducting polymer containing synthetic molecular... 

Figure 15. Preparation of Conducting Polymer Containing Synthetic Molecular Receptors...

M. Omastova, S. Kosina, J. Pionteck, A. Janke, and J. Pavlinec. Electrical properties and stability of polypyrrole containing conducting polymer composites. Synthetic Metals 81,49-57 (1996). 

Figure 13 shows the irreversible conversion of a nonconjugated poly (p-phenylene pentadienylene) to a lithiun-doped conjugated derivative which has a semiconducting level of conductivity (0.1 to 1.0 S/cm) (29). Obviously, the neutral conjugated derivative of poly (p-phenylene pentadienylene) can then be reversibly generated from the n-type doped material by electrochemical undoping or by p-type compensation. A very similar synthetic method for the conversion of poly(acetylene-co-1,3-butadiene) to polyacetylene has been reported (30), Figure 14. This synthesis of polyacetylene from a nonconjugated precursor polymer containing isolated CH2 units in an otherwise conjugated chain is to be contrasted with the early approach of Marvel et al (6) in which an all-sp3 carbon chain was employed.

An alternative and often facile route to appropriately functionalised ICPs, that avoids the synthetic problems outlined in (ii) above, is the use of sulfonated species containing the desired molecular recognition/receptor site as the dopant anion for the conducting polymer chains. For example, calixarene-containing polypyrroles [34] and polyanilines [35] for selective metal ion detection have recently been prepared via the use of sulfonated calixarenes as dopant anions. We have similarly found that the incorporation of metal complexing agents such as sulfonated 8-hydroxyquinoline as dopants in polypyrroles provides a simple route to metal ion-selective ICPs [36]. 

Chemical polymerization onto sulfonated (dopant-containing) synthetic polymers has also been described.45 Sulfonated polyethylene-polystyrene was exposed to monomer and then the oxidant. A mixture of Fe11 and Fem led to more accurate control of the E° value of solution. These same workers also described a novel chem-ical/electrochemical method, in which pyrrole was initially polymerized using a low concentration of Fe111. The reduced Fem could then be reoxidized electrochemically to regenerate the oxidant. Using this chemical/electrochemical process, composite polymers with conductivities as high at 35 S cm-1 were obtained. 

Xiao et al. investigated the electrochemical synthetic mechanism of conducting-polymer nanotubes in a porous alumina template using poly(3,4-ethylenedioxythiophaie) (PEDOT) as a model compound [70]. The electrochemical polymerization of EDOT was performed potentiostatically at various potentials from 1.0 to 1.8 V (vs. Ag/AgCl) in a solution containing EDOT, LiC104, and acetonitrile. They found that the tubular portion of the nanotube structure increased as the applied potential increased from 1.4 to 1.8 V at a fixed concentration of EDOT, while the tubular portion decreased with increasing monomer concentration from 10 to 100 mM at a fixed poteitial of 1.6 V. 

Thiophene was found in tar, gas and industrial benzene obtained from coal in the nineteenth century. A large number of thiophene derivatives are described in the literature and their physical properties, nucleophilic substitution and biological activity are still of current interest [ ] As for polymers, thiophene was oxidized by such acidic materials as orthophosphoric acid or a synthetic silica-alumina catalyst to yield liquid oligomer which consisted of its trimer containing a small amount of its pentamer. A report on this was published as early as 1883 [2], However, modem studies on polythiophene, aiming at the preparation of electrically conductive polymers, started at the beginning of the 1980s [3-5]. 

This section reviews the synthesis and characterization of random, alternating, block and graft copolymers of thiophenes. A review [2] of processable electronically conducting polymers published in 1991 contains only two references on polythiophene random copolymers and another article [3] describes the synthetic methods used to prepare block and graft copolymers of thiophene. 

Shaped articles, e.g. rods, fibers, and films, which are electrically conductive can be manufactured from composites containing a nonconductive flexible chain-carrier polymer and a conjugated polymer (e.g., POT, PDDT, poly-(thienylene vinylene)) [831,832]. Polyester blends containing PT can be used as synthetic fibers [833]. Electrically conductive resin adhesives, heat, stock, and moisture resistant with bifunctionality as adhesives and solders can consist of epoxy methacrylates and conducting polymers, e.g., PDDT, PODT [834,835]. 

Polymers containing thiophene systems have been a subject of research for more than twenty five years. One of the first examples was the polymer with thiophene units and conjugated double bonds [ poly(2.5-thiophenediylvinylene)]. It has been studied intensively because of its good electrical conductivity, being a member of the family of synthetic metals or organic metals. 

While Wegner s hypothesis is currently controversial, it is one that deserves the synthetic chemists attention, because it opens a second potential avenue of approach to conducting polymers, namely the use of non-conjugated polymers containing aromatic moieties. Such polymers should have improved processability, mechanical properties and oxidative stability with respect to conjugated polymers. 

This chapter reviews the chemistries, properties, and commercial uses water-containing ionicaUy conductive polymer systems. In medical applications, these polymers serve as the conductive interface between the patient s skin and the medical equipment. These electrolyte systems are commercially produced in gel, paste, or sheet form using either natural or synthetic polymers. Regardless of the physical form, these systems are typically formulated to a conductivity range of 10 to 10 S cm to provide acceptable performance. A new plication of this type of polymer is reported recently in the prevention of steel rebar corrosion in concrete structures. 

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