Polymers become conducting when they have conjugated double bonds along their carbon backbone that allow for electron movement. There are two types of conducting polymers - p-type polymers that conduct positive holes and n-type polymers that conduct negative electrons. Important examples include polyacetylene, polyaniline, and PEDOT. Potential applications of conducting polymers include uses in batteries, solar cells, LEDs, electromagnetic shielding, and anti-static coatings due to their ability to combine electrical conductivity with plastic-like mechanical properties.

1. Vinit Shahdeo
15BIT0335|SITE
Conducting Polymers
3RD
DIGITAL ASSIGNMENT
ENGINEERING CHEMISTRY
E2 SLOT
B.TECH-IT

2. Polymers are usually organic substances composed of a very large
number of like molecules.
Polymers are divided, on the basis of their mechanical properties and
strength, into three categories: rubbers or elastomers, plastics and
fibers.
Polymers are generally insulators because the organic molecules of
which they are composed have no free electrons to carry current; all
the electrons are held firmly by atoms forming the molecules.
Polymers in which the carbon atoms in the backbone are linked by
double bonds have the potential to conduct electricity, especially
when a number of such bonds occur in the vicinity of each other are
known as Conducting Polymers.
Conductive polymers or more precisely intrinsically conducting
polymers (ICPs) are organic polymers that conduct electricity.
Such compounds may have metallic conductivity or behave as
semiconductors. Conductive polymers combine the mechanical
properties (flexibility, toughness, malleability, elasticity, etc.) of
plastics with high electrical conductivity. These properties can be
fine-tuned using different methods of organic synthesis.
In 1977, Alan J. Heeger, Alan MacDiarmid and Hideki Shirakawa
proved that polyacetylene doped (oxidised) with iodine has high
conductivity. This research earned them the 2000 Nobel Prize in
Chemistry. It has great applications in day to day life.
INTRODUCTION

3. MECHANISM OF CONDUCTION
It is generally agreed that the mechanism of conductivity in these polymers is based on the motion of
charged defects within the conjugated framework. The charge carriers, either positive p-type or negative
n-type, are the products of oxidizing or reducing the polymer respectively. The following overview
describes these processes in the context of p-type carriers although the concepts are equally applicable
to n-type carriers.

4. Conducting polymers have a
continuous chain of sp2
hybridized carbon centers.
It is these π bonds due to
which they conduct.
Two conditions:
 Presence of conjugated
double bonds.
 Molecule has to be
disturbed- using a
dopant.
Oxidative doping
(halogens): P-type
semiconducting Polymer
Reductive doping (alkali
metals): N-type
semiconducting polymer
HOW DO THEY CONDUCT?

5. FEW COMMON EXAMPLES OF CONDUCTING POLYMERS

6. Conducting polymers have many uses. The most documented are as
follows:
 Anti-static substances for photographic film
 Corrosion Inhibitors
 Compact Capacitors
 Anti Static Coating
 Electromagnetic shielding for computers
 "Smart Windows"
A second generation of conducting polymers have been developed
these have industrial uses like:
 Transistors
 Light Emitting Diodes (LEDs)
 Lasers used in flat televisions
 Solar cells
 Displays in mobile telephones and mini-format television screens
APPLICATIONS OF CONDUCTING POLYMERS

7.  For conductance free
electrons are needed.
 Conjugated polymers are
semiconductor materials
while doped polymers are
conductors.
 The conductivity of
conductive polymers
decreases with falling
temperature in contrast
to the conductivities of
typical metals, e.g. silver,
which increase with
falling temperature.
 Today conductive plastics
are being developed for
many uses.
CONDUCTING POLYMERS

8. There are two main groups of applications for these polymers. The first group
utilizes their conductivity as its main property. The second group utilizes their
electroactivity.
Group 1 Group 2
Electrostatic materials Molecular electronics
Conducting adhesives Electrical displays
Electromagnetic shielding Chemical biochemical and thermal sensors
Printed circuit boards Rechargeable batteries and solid electrolytes
Artificial nerves Optical computers
Antistatic clothing Ion exchange membranes
Piezoceramics Electromechanical actuators
Diodes/Transistors 'Smart' structures
Aircraft structures Switches
APPLICATIONS OF CONDUCTING POLYMERS

10. SMART WINDOWS
Shield for computer screen
against electromagnetic
"smart" windows
radiation
Smart Windows

11. APPLICATIONS

12. CONCLUSION
Due to their poor processability, conductive polymers have few large-scale applications. They have
promise in antistatic materials and they have been incorporated into commercial displays and
batteries, but there have had limitations due to the manufacturing costs, material inconsistencies,
toxicity, poor solubility in solvents, and inability to directly melt process. Literature suggests they
are also promising in organic solar cells, printing electronic circuits, organic light-emitting
diodes, actuators, electrochromism, supercapacitors, chemical sensors
and biosensors, flexible transparent displays, electromagnetic shielding and possibly
replacement for the popular transparent conductor indium tin oxide. Another use is
for microwave-absorbent coatings, particularly radar-absorptive coatings on stealth aircraft.
Conducting polymers are rapidly gaining attraction in new applications with increasingly processable
materials with better electrical and physical properties and lower costs. The new nanostructured
forms of conducting polymers particularly, augment this field with their higher surface area and
better dispersability.
With the availability of stable and reproducible dispersions, PEDOT and polyaniline have gained
some large scale applications. While PEDOT (poly(3,4-ethylenedioxythiophene)) is mainly used in
antistatic applications and as a transparent conductive layer in form of PEDOT:PSS dispersions
(PSS=polystyrene sulfonic acid), polyaniline is widely used for printed circuit board manufacturing
– in the final finish, for protecting copper from corrosion and preventing its solderability.