WHAT ARE CONDUCTING POLYMERS CPs

When one thinks of polymers, one perhaps envisions common plastics, such as polythene, that one may encounter in everyday life. If one then conjures up a conducting polymer, one may perhaps envision these plastics filled up with conductors such as metal or carbon particles. The Conducting Polymers (CPs, also sometimes called Conductive Polymers or Conjugated Conductive Polymers or Organic Polymeric Conductors), which are the subject of this book, are quite a different beast, in the sense that they are intrinsically conducting, and do not have any conductive fillers as such. 

This unique intrinsic conductivity of these organic materials, which generally are comprised simply of C, H and simple heteroatoms such as N and S, and the myriad of properties emanating from it, arise uniquely from v-conjugation. That is to say, a sometimes fairly extended and delocalized conjugation originating in overlap of ir-electrons. Such conjugation is illustrated somewhat simplistically in Fig. 1-1 below for poly(acetylene), a prototypical CP. 

This conductivity of CPs is achieved through simple chemical or electrochemical oxidation, or in some cases reduction, by a number of simple anionic or cationic species, called dopants. That is to say, the polymeric backbone of these materials needs to be oxidized or reduced to introduce charge centers before conductivity is observed, and the oxidation or reduction is performed by anions or cations somewhat misnamed dopants, a term borrowed from condensed matter physics. 

Thus in an elementary fashion and if we consider the three broad materials categories of insulators, semiconductors and conductors (such as metals), CPs differ from typical everyday organic polymers such as poly (ethylene), poly(vinylidene chloride) ( Saran wrap), polyesters (used in textiles) and other everyday plastics, which are generally highly insulating, in that tlieir unique 7r-electron properties impart electrical conductivity at room temperature, and many other derivative and interesting properties discussed at length in this book, on oxidation or reduction. 

In the CP literature and among workers in the field, the monomers are generally represented by abbreviations, e.g. ANi for aniline, and the polymer also abbreviated in short-hand notation, following the custom in other polymer literature. For example, P(ANi) and PANi may be used to represent poly (aniline), P(Py) and PPy poly (pyrrole), and P(3MT), P3MT or PMT may be used to represent poly (3-methyl-thiophene). 

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