a) b - École Polytechnique de Montréal

Although polymer and carbon-black composites are versatile, relatively inexpensive, and
permanently conductive, there are several disadvantages related to the use of carbon black. The
possibility of contamination of clean-room environments by shedding of carbon particles, a
process known as sloughing, makes it unusable in many areas. Also, the level of conductivity for
a particular resin is hard to control because of the steepness of the percolation curve (Figure 2-
25). Thereby, resistivity levels ranging from 10 6 to 10 9 Ω are hard to reach, and also other
conductivity values are not completely reproducible.
2.3.1.2 Intrinsically Conductive Polymers
Applications of conductive polymers have been extended during the last years, with the emphasis
being to make better, smaller and faster electronic instruments. A few years ago, semiconductor
silicon was the only material used to fabricate almost all electronic devices. Around 16 million
bits of information can be stored by an advanced silicon chip in an area of less than 1 cm 2 ,
although a practical limit to the density of stored information in a chip exists. With further
decreasing of the size, overheating occurs and electronic components do not work properly. To
overcome this limitation, it has been suggested to use conductive polymers as a conventional
semiconductor. Moreover, polymers have the advantages of flexibility, lightweight, high
chemical inertness, corrosion resistivity, and ease of processing.
Intrinsically conductive polymers have caused a dramatic change in polymer architecture. A key
property of a conductive polymer is the presence of conjugated double bonds along the backbone
of the polymer. A regular chemical bond (C–C) occurs when two atoms share a pair of electrons.
Such sharing of electrons allows atoms to bind together and keeps molecules from flying apart.
A double bond denoted as (C=C) occurs when the atoms share an extra pair of electrons.
Conjugation occurs when there are single and double bonds alternating along the polymer chain
in a π-conjugated system of the conductive polymers(Gerard, Chaubey, & Malhotra, 2002;
Inzelt, Pineri, Schultze, & Vorotyntsev, 2000; Pron & Rannou, 2002). Consequently, electrically
conducting polymers are composed of macromolecules having fully conjugated sequences of
double bonds along the chains. It implies that in intrinsically conductive polymers, the polymer
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