Mumbai University > First Year Engineering > Sem1 > Applied Chemistry 1

Marks: 6M

Year: Dec 2013

ICP –

These possess conjugated pie electrons backbone. When such a polymer faces electric field, these electrons get excited, and hence, move through polymeric material.

The orbitals of conjugated pie electrons get overlapped on the backbone and hence valence bands and conduction bands are developed which get distributed over entire surface of polymer. Appropriate proportion of conjugated pie electrons makes polymer to conduct electricity very efficiently.

Eg- polyacetylenes, polyquinoline, poly-p-phenylene etc.

Aromatic- polyaniline, polyanthrylene.

Aromatic heterocyclic- polypyrrole, polythiophene etc.

DCP -

These are prepared by exposure of the polymer to a charged transfer agent either in gas phase or in liquid phase.

As compared to plain ICP, these have low I.P but high E.A. hence these can be easily oxidized or reduced.

ICP can be made more conductive by creating +ive or –ive charge on itd backbone by oxidation or reduction. This technique is called as Doping.

There are two types of doping –

1. P- doping

   P-doping is a technique in which an ICP is oxidized with lewis acid, creating the charge on backbone of polymer. The lewis acid used are known as p-dopant. E.g.- $I_2, Br_2, ASF_5$, naphthylamine etc.

2. N-doping- this technique involves reduction of ICP with lewis base to form negative charge on backbone of ICP. E.g. - Li, Na, Cu etc.