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Conducting polymers

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Introduction to conducting polymers

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Conducting polymers

  1. 1. 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?
  2. 2. 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.
  3. 3. 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
  4. 4. Conducting Polymers Mechanism of Conduction ● Flow of electron from atoms toatoms ● Now if any material having free electrons which canmove will beconducting
  5. 5. Mechanism of Conduction ● Band gap Conducting Polymers
  6. 6. Conducting Polymers Conducting Polymers Intrinsic Conducting polymers Extrinsic Conducting polymers
  7. 7. Conducting Polymers Intrinsically conducting polymers ● Conducting polymersarealsocalled synthetic metals ● Intrinsicallyconducting polymers are conjugated materials. ● Theycontain alternating doubleand single bonds in their backbone. Polyacetylene Polypyrrole
  8. 8. 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.
  9. 9. Conducting Polymers Conduction mechanism Intrinsically conducting polymers
  10. 10. 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.
  11. 11. ● 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
  12. 12. 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
  13. 13. 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.
  14. 14. Conducting Polymers ● Comparison of conductivity withmetals Intrinsically conducting polymers

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