Alan Heeger, MacDiarmid, and Shirakawa discovered that the polymer polyacetylene can be made conductive like a metal when doped. Conducting polymers have overlapping conjugated pi-electrons in their backbone that form valence and conduction bands, allowing electricity to flow. Intrinsically conducting polymers are conjugated materials with alternating single and double bonds that contain delocalized pi-electrons responsible for their optical and electrical properties.

2. Conducting Polymers
Introduction
● Usually, Polymers are considered as insulatingmaterials
● Polymers are one of the most used materials in the modern
world. Their uses and application range from containers to
clothing
● Theyare used tocoat metal wires to preventelectric
shocks.
● Brain, neuron are biologicalpolymers
● How they transmit signals within the body?

3. Conducting Polymers
● Introduction
Alan J. Heeger, Alan G. MacDiarmid and Hideki Shirakawa have changed
this view with their discovery that a polymer, polyacetylene, can be made
conductive almost like ametal.

4. Conducting Polymers
Introduction
● A polymerwhich can conductelectricity is termed as
conducting polymer.
● It is being said thatonedayconducting polymers may
be used in placeof metals in electrical wiring.
● Lighterweight.
● They do notcorrode

5. Conducting Polymers
Mechanism of Conduction
● Flow of electron from atoms toatoms
● Now if any material having free electrons which canmove
will beconducting

6. Mechanism of Conduction
● Band gap
Conducting Polymers

7. Conducting Polymers
Conducting Polymers
Intrinsic Conducting polymers Extrinsic Conducting polymers

8. Conducting Polymers Intrinsically conducting polymers
● Conducting polymersarealsocalled synthetic metals
● Intrinsicallyconducting polymers are conjugated
materials.
● Theycontain alternating doubleand single bonds in
their backbone.
Polyacetylene
Polypyrrole

9. Conducting Polymers Intrinsically conducting polymers
● Such polymers contain conjugated pie-electrons in the
backbone which increases their conductivity to a large
extent.
● Overlapping of conjugated pie-electrons over the entire
backbone results in the formationof valence bands as well
as conduction bands.
● Thevalence band and theconduction bands areseparated
by a significant bandgap.

10. Conducting Polymers
Conduction mechanism
Intrinsically conducting polymers

11. Conducting Polymers Intrinsically conducting polymers
Conduction mechanism
● The bands should be partially filled in order to be
electricallyconducting, as neitherempty nor full bands can
carryelectricity
● Owing to the presenceof partially filled energy bands,
metals have highconductivities
● The energy bands of insulators and semiconductors,
however, areeithercompletely full orcompletelyempty.

12. ● Electrical conduction could occur only after thermal or photolytic
activationof electrons togive them sufficientenergy to jump thegap
and reach intothe lower levels of theconduction band
● Examples
Conducting Polymers Intrinsically conducting polymers

13. Conducting Polymers
Conduction mechanism inpolyacetylene
● Unsaturated polymersconsistsof hydrogenand sp2 hybridized carbon
atoms
Intrinsically conducting polymers
● The localized electrons form the backboneof polymerchain and
dominate the mechanicalproperties.
● The electrons in the pi bond are delocalized along the chain and are
responsible foroptical and electrical propertiesof conjugated polymers

14. Conducting Polymers
Conduction mechanism inpolyacetylene
● Thecurrentalong the polymerchainscan only flow if oneor more
electronsare removed oradded to it.
Intrinsically conducting polymers
● The loneelectronof pi bond from which an electronwas removed can
moveeasily.
● Due tothis, the double bond successively movesalong thechain.

15. Conducting Polymers
● Comparison of conductivity withmetals
Intrinsically conducting polymers