Intrinsically Electrically Conducting Polymers ICPs

For many years it has been common practice to improve the electrical conductivity of plastics and rubbers by incorporating certain additives, such as special grades of carbon black. Such compounds have been important, for 

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 ptolymers depend on the presence of particles which can transport or carry an electric charge. Two types may be distinguished  

An example of an ionically conductive polymer is polyethylene oxide containing LiC104, which is used as a solid phase electrolyte in batteries. 

The polymers which have stimulated the greatest interest are the polymers of acetylene, thiophene, pyrrole and aniline, poly-p-phenylene, polyphenylvinylene and poly-l,6-heptadiyne. Of these materials polypyrrole has been available from BASF under the trade name Lutamer PI60 since 1988. 

The properties and applications of intrinsically conductive polymers have been reviewed (Frommer and Chance, 1986 Sauerer, 1991). The important poly-pyrolles have been separately reviewed (Jasne, 1988). 

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Recently the question has been raised as to whether the electrical conductivity of isolated mesoscopic metal particles, that is particles in the submicrometer order of magnitude, and of intrinsic conductive polymers (ICP) have some properties in common. In this section we outline the metallic properties and the origin of mesoscopic conductivity (small metal particles). 

In order to render a plastic conductive although it is, by nature, an electrical and thermal insulator (with the exception of intrinsically conducting polymers, ICPs), we need to dope it with electrically conductive fillers such as steel microfibers (pFSs) [FEL 06], CNPs [FEL 01] or indeed carbon nanotubes [FEL 11]. By gradually varying the proportion of fillers in the polymer matrix, we see that its resistance goes... 

Keywords Electromagnetic interference (EMI) shielding, microwave absorption, electrical conductivity, nanocomposites, intrinsically conducting polymers (ICPs), polyaniline, carbon nanotubes, graphene, shielding effectiveness, reflection loss, absorption loss, complex permittivity and permeabdity... 

An organic polymer that possesses the electrical and optical properties of a metal while retaining its mechanical properties and processability, is termed an intrinsically conducting polymer (ICP). These properties... 

Polymers are usually considered as insulators because of their higher electrical resistance values, ie, 10 S/cm [21]. However, there is a new class of polymers that is known as intrinsically or inherently conductive polymers (ICPs) and also as conjugated polymers or unluckily as organic metals and electroactive polymers, which should be reserved for actuating materials. They are still in a developing phase. 

Furthermore, intrinsically conducting polymers (ICPs) such as polyanilines (PANI), polypyrroles, and polyphenylenes have been used as part of conductive composites on account of their much higher conductivity than other polymers. They are often mixed with other polymers as investigated by Taipalus (2001) and Totsra and Friedrich (2004). On the other hand Dweiri (2007) have found the addition of PANI to a composite of PP/carbon black/graphite for bipolar plates to be unsuitable for processing due to the poor thermal stability of PANI. The company Bac2 is currently the only manufacturer to use a patented electrically conductive polymer called ElectroPhen in their composite bipolar plates. 

One of the main limitations of intrinsically conductive polymers (ICP s) towards their wide application as conductive additives for thermoplastics is their poor thermal-oxidative stability at typical melt processing temperatures (i.e., above 200 °C). On the other hand, the use of high surface area carbon blacks (CB) as conductive additives is limited due to the increased melt viscosity of their blends with thermoplastics. Eeonomers are a new class of thermally stable, chemically neutral, and electrically conductive composites made via in-situ deposition of conductive polyaniline (PANI) or polypyrrole (PPY) on CB substrates. Eeonomer composites are more stable (up to 300 °C) than pure ICP s and more easily processible with thermoplastics than CB. Use of Eeonomers as conductive additives for plastics lead to compounds with improved electrical, mechanical, and processing properties. By varying Ae conductive polymer to CB ratio, it is possible to fine tune the polarity of Eeonomer composites and achieve very low percolation thresholds. This control is possible because of preferred Monomer localization at the 2D phase boundary of the immiscible polymer blends. 

Today, however, there are signs of new ways and means of achieving electrical conductivity in plastics. New kinds of polymers, known as intrinsically conductive polymers (ICPs), have been developed whose electrical conductivity is no longer due to additives but to their chemical and crystalline structure, or morphology. 

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