Conducting Polymer 7496f

SHARDA UNIVERSITY

APPLIED CHEMISTRY CHY-102

CONDUCTING POLYMERS Ô SUBMITTED BY:Ú ñUNAL ñAPUR Ú MD.MANJAR HUSSAIN Ú ANIMESH JAISWAL Ú ñAVISH SATIJA Ú JITESH CHAWLA Ú AñSHEY BAJAJ

SUBMITTED TO:DR.NOOPUR SHRIVASTAV

CONDUCTING POLYMERS A polymer which can conduct electricity is termed as conducting polymer. EXAMPLES: 1.Polyaniline is used to make rechargeable batteries in the shape as flat buttons or as laminated rolled films. 2.Polypyrrole is used in µsmart¶ windows .These smart windows can change their colour in response to changes in temperature or amount of sunlight. The colour change is from a transparent yellow-green to blue-black.

ADVANTAGES G It is being said that µone day conducting polymers may be used in place of metals in electrical wiring.¶. G Lighter weight. G They do not corrode.

V VI

I ISIVA V VI S

X ISIVA V VI S

INTRINSICALLY CONDUCTING POLYMERS

CONDUCTING POLYMERS HAVING CONJUGATION

DOPED CONDUCTING POLYMERS

EXTRINSICALLY CONDUCTING POLYMERS

CONDUCTING ELEMENTS FILLED POLYMER

BLENDED CONDUCTING POLYMEERS

INTRINSICALLY CONDUCTING POLYMERS These polymers have extensive conjugation in the backbone which is responsible for conductance.

CONDUCTING POLYMERS HAVING CONJUGATION G Such polymers contain conjugated pie-electrons in the backbone which increases their conductivity to a large extent. G Overlapping of conjugated pie-electrons over the entire backbone results in the formation of valence bands as well as conduction bands. G The valence band and the conduction bands are separated by a significant band gap.

G Electrical conduction could occur only after thermal or photolytic activation of electrons to give them sufficient energy to jump the gap and reach into the lower levels of the conduction band. G EXAMPLES: (1)POLYACETYLENE

(2)POLYPYRROLE

(3) POLYANILINE

GDISADVANTAGE Conductivity of these polymer, having conjugated pie-electrons in the backbone is not sufficient for their use in different applications.

DOPED CONDUCTING POLYMERS These polymers have doping of positive or negative charge on polymer backbone. Conductivities of previous type can be increased by creating positive or negative charge on polymer backbone by oxidation or reduction.

GP-DOPING It is done by oxidation process. Conducting polymers of previous type is treated with lewis acid (A) or with iodine vapour or iodine in CCl4.

GN-DOPING It is done by reduction process. Conducting polymer of previous type is treated with lewis base (B) like sodium naphthalide.

V



Dopants

HCl

BF4-,ClO4-

Tosylate

Conductivity (S cm-1)

1000

500-7500

1000

FACTORS INFLUENCING THE CONDUCTIVITY OF ORGANIC POLYMERS

G Conjugation length of the polymer chain. G Doping Level. G Temperature. G Frequency of current.

INTERSTING RANGE OF PROPERTIES OFFERED BY INTRINSICALLY CONDUCTING POLYMERS GC

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G A ilit t

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G A ilit t i GA r G Tr

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f i i l li t

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SUCCESSFUL APPLICATION DEPENDS ON ACHIEVING THE FOLLOWING FEATURES : G Advantage in processing. G Excellent properties in products. G Economy. G Good product stability. G More efficient recycling. G Demonstration of ecological advantages.

LIMITATIONS OF INTRINSICALLY CONDUCTING POLYMERS G Their conductivities are inferior to metal. m

VV

POLYACETYLENE

400000 S cm-1

Cu

600000 S cm-1

G Improcessibility. G Poor mechanical strength. G Poor stability under exposure to common environmental conditions, particularly at elevated temperatures. G Poor storage stability leading to loss in conductivity.

EXTRINSICALLY CONDUCTING POLYMERS G These polymers owe their conductivity due to the presence of externally added ingredients in them.

CONDUCTIVE ELEMENT FILLED POLYMER G In this, the polymer acts as the binder to hold the conducting element (such as carbon black, metallic fibers, metallic oxides,etc.) together in the solid entity. G Generally, special conducting grade CBlack is used as filler which has very high surface area, more porosity and more of filamentous properties.

GADVANTAGES Ú Good bulk conductivity. Ú Low in cost. Ú Light in weight. Ú Mechanically durable and strong. Ú Easily processable in different forms, shapes and sizes.

GDISADVANTAGE Ú Addition of as little as 10% carbon black will drastically reduce the tensile strength.

BLENDED CONDUCTING POLYMERS G These polymers are obtained by blending a conventional polymer with a conducting polymer. Such polymers possess better physical, chemical, electrical and mechanical properties and they can be easily processed.

For example :upto 40% of polypyrrole will have little efffect on tensile strength than obtained with a carbonblack filled compound at only 10% loading.

APPLICATIONS OF CONDUCTING POLYMERS G IN RECHARGEABLE BATTERIES G IN ANALYTICAL SENSORS G FOR MAñING ION-EXCHANGERS G IN ELECTROCHEMICAL DISPLAYS AND OPTICAL FILTERS G IN ELECTRONICS G IN PHOTOVOLTAIC DEVICES

THANñ YOU FOR YOUR ATTENTION