Q. Write short note on "Electrically conducting polymers".
Ans. electrically conducting polymers: Many synthetic organic polymers have been found to possess high electrical conductivity. Catalyst of some of these polymers exhibits superconductivity at low temperature. This is due to their crystal lattice in which electron-donor and acceptor molecules are stacked one over the other. Such organic crystalline substances are placed in the category of organic electronic material. Synthetic organic polymers that are intrinsically insulating, can conduct electricity after doping them with suitable Dopants. Dopants are the chemical substances that are either electron donor or electron-acceptors. Electron-acceptor Dopants or p-type (holes dominant) like acids (HCl, HNO3 etc.) possess oxidizing property and they are said to be exert p-doping effect. Some examples of polymers, which when doped are electrically conducting properties.
Factors affecting the conductivity of organic polymer:
1. Doping level: The conductivity of conjugated polymers increases length f their doping level.
2. Conjugation: The conductivity increases rapidly with increasing conjugation length to the chain.
3. Temperature: the conductivity increases with increase in temperature. This is reverse of the metals where the temperature increases the conductivity decreases.
4. Current frequency: the conductivity is strongly dependent on current frequency. It plays an important role on doping.
Applications:
(1) In solid batteries.
(2) In rechargeable batteries based on par chlorate doped oxyacetylene lithium systems.
(3) In sensors used for making sensors.
(4) In microelectronic devices useful for electron lithography and data storage.
(5) In solar cells.
(6) As drug delivery systems.
(7) In telecommunication systems.
(8) For making ion exchangers.
In wiring of aircrafts and aerospace components.