Polymers are generally known for their insulating property.
But in the mid-1970s, the first polymer capable of conducting electricity, polyacetylene, was reportedly prepared by accident by Prof. Hideki Shirakawa. The subsequent discovery by Alan Heeger and Alan MacDiarmid that the polymer would undergo an increase in conductivity of 12 orders of magnitude by oxidative doping quickly reverberated around the polymer and electrochemistry communities, and an intensive search for other conducting polymers soon followed.
In the late seventies, Alan MacDiarmid, Hideki Shirakawa, and Alan Heeger, along with a group of young students started research in the field of conducting polymers and the ability to dope these polymers over the full range from insulator to metal. This was particularly exciting because it created a new field of research and a number of opportunities. Electronically conducting polymers are extensively conjugated in nature.
It is generally agreed that the mechanism of conductivity in these polymers is based on the motion of charged defects within the conjugated framework. Since the late seventies, a large number of polymers have been added to the list of conducting polymers such as polypyrrole, polythiophene, poly para phenylene, polyphenylene sulphide, polyaniline, polyphenylene vinylene, etc.
Conjugated organic polymers are either electrical insulators or semiconductors that can become highly electrically conductive after incorporation of acceptors or donors a process called “doping”. The doping process results in dramatic changes in the electronic, electrical, magnetic, optical, and structural properties of the polymer. The doping process is reversible, and it produces the original polymer with little or no degradation of the polymer backbone.
Conducting polymers find application in a large variety of areas which is due to their conductivity and redox properties. Some of the interesting application areas are anticorrosion paint, Antistatic, EMI Shielding, RADAR absorbing materials, Catalysis, Supercapacitor, Sensors, Membrane, etc. Interest in research on conducting polymers has grown after the 2000 Nobel prize and people found a way to make polymer processible.
Conducting polymers are a good candidate in different applications for the following reasons –
• ease of fabrication
• low production cost
• easy to interface with electronic devices such as MEMS
• Long life
• High stability
• Environmental friendly
• Easy to dispose
• Tune the polymer according to need