Polymers electrically conducting

Various copolymers with the basic backbone of —Ar—NH—Ar—S—, i.e., aromatic amino sulfide copolymers have been synthesized. This type of copolymer is semiconducting and can be used in many electronic and electro-optical applications. Examples of such applications are antistatic layers, electromagnetic-shielding layers, anticorrosion layers, batteries, electroluminescent devices, and in electronic circuits, such as conductor tracks of transistors. 

Polymers with molecular weights greater then 10 Dalton can be dissolved, up to 20%, in DMF, THF, NMP and dimethylacetonitrile, and in particular in dimethyl sulfoxide. 

The polymer is stable at temperatures up to 380°C. Optically clear, self-supporting layers having a modulus of elasticity of 1.3 GPa can be prepared from a solution. Layers of the polymer adhere very well to metals, in particular to gold. By means of oxidation agents, PPSA can be doped to form a p-type material. Doping of a self-supporting layer of PPSA with 

SbCls results in an electric conductivity of 0.18 S cm, while doping with FeCls leads to a conductivity of 0.8 Scm.  

Department of Applied Chemistry, Aligarh Muslim University, Aligarh-202002, India 

Handbook of Advanced Electronic and Photonic Materials and Devices, edited by H.S. Nalwa 

Volumes.- Conducting Polymers Copyright 2001 by Academic Press All rights of reproduction in any form reserved. 

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Reversible oxidation and reduction of polymers is commonly used to increase conductivity in these systems. Ions from the electrolyte are usually incorporated into the polymer as part of this process (see Electrically conducting polymers). 

Functionalized conducting monomers can be deposited on electrode surfaces aiming for covalent attachment or entrapment of sensor components. Electrically conductive polymers (qv), eg, polypyrrole, polyaniline [25233-30-17, and polythiophene/23 2JJ-J4-j5y, can be formed at the anode by electrochemical polymerization. For integration of bioselective compounds or redox polymers into conductive polymers, functionalization of conductive polymer films, whether before or after polymerization, is essential. In Figure 7, a schematic representation of an amperomethc biosensor where the enzyme is covalendy bound to a functionalized conductive polymer, eg, P-amino (polypyrrole) or poly[A/-(4-aminophenyl)-2,2 -dithienyl]pyrrole, is shown. Entrapment of ferrocene-modified GOD within polypyrrole is shown in Figure 7. 

Polypyrroles. Highly stable, flexible films of polypyrrole ate obtained by electrolytic oxidation of the appropriate pyrrole monomers (46). The films are not affected by air and can be heated to 250°C with Htde effect. It is beheved that the pyrrole units remain intact and that linking is by the a-carbons. Copolymerization of pyrrole with /V-methy1pyrro1e yields compositions of varying electrical conductivity, depending on the monomer ratio. Conductivities as high as 10 /(n-m) have been reported (47) (see Electrically conductive polymers). 

Practical appHcations have been reported for PVP/ceUulosics (108,119,120) and PVP/polysulfones (121,122) in membrane separation technology, eg, in the manufacture of dialysis membranes. Electrically conductive polymers of polyaruline are rendered more soluble and hence easier to process by complexation with PVP (123). Addition of small amounts of PVP to nylon 66 and 610 causes significant morphological changes, resulting in fewer but more regular spherulites (124). 

Common conductive polymers are poly acetylene, polyphenylene, poly-(phenylene sulfide), polypyrrole, and polyvinylcarba2ole (123) (see Electrically conductive polymers). A static-dissipative polymer based on a polyether copolymer has been aimounced (124). In general, electroconductive polymers have proven to be expensive and difficult to process. In most cases they are blended with another polymer to improve the processibiUty. Conductive polymers have met with limited commercial success. 

Generally speaking, electrically conductive polymers are composed of conjugated polymer chains with TT-electrons delocalized along the backbone. 

Chapters 10 to 29 consisted of reviews of plastics materials available according to a chemical classification, whilst Chapter 30 rather more loosely looked at plastics derived from natural sources. It will have been obvious to the reader that for a given application plastics materials from quite different chemical classes may be in competition and attempts have been made to show this in the text. There have, however, been developments in three, quite unrelated, areas where the author has considered it more useful to review the different polymers together, namely thermoplastic elastomers, biodegradable plastics and electrically conductive polymers. 

Electrically conductive polymers are just one of a number of esoteric possible uses for synthetic polymers. These materials are now being considered for a variety of applications. 

During the past 30 years considerable research has been undertaken that has led to electrically conducting polymers that do not rely on the use of fillers, the so-called intrinsically conductive polymers. Such polymers depend on the presence of particles which can transport or carry an electric charge. Two types may be distinguished ... 

Frommer JE, Chance RR (1986) in Electrically conductive polymers, in Grayson M, Krosch-witz J (eds) Encyclopedia of Polymer Science and Engineering, 2nd edn, Wiley, New York, vol 5 p 462... 

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