New Friday Meeting

7/31/2019 New Friday Meeting

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PANI-?


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Conducting Polymers

Conductivity

Outline


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Polymers are long chain like molecular structure

where repeated molecular units are connected by

covalent bonds

Monomers are the building blocks .

Introduction

Monomer Polymer

Amino Acid Protein

Vinyl chloride

n(C2H3Cl)

Polyvinyl Chloride (PVC)

(-C2H3Cl-)n

Aniline Polyaniline


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Polymers with conducting material on its

backbone

1977- Alan Heegar , Hideki Shirakawa and AlanMacdiarmid

Conducting Polymers


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Advantages over Conductors:

Redox behavior

Catalytic properties

Electrochemical effect

Mechanical - light weight , flexible , nonmetallic surface properties

High conductivity at nano scales[1]

Discovery of conducting polymers

[1]Terje A. Skotheim and John R. Reynolds, Conjugated Polymers:

Theory, Synthesis, Properties, and Characterization Handbook of

Conducting Polymers 3rd ed. CRC Press (2007).


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1. Insulating polymer filled with conducting

fillers

2. Ionically conducting polymers

3. Redox Polymers

4. Conjugated polymers

Types of Conducting Polymers


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inherently conducting in nature due to the

presence of a conjugated -electron system in

their structure.

have a low energy optical transition

low potential

electron affinity

Cojugated polymers


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Polymers become conducting upon doping

Polymer becomes electronically charged

Polymer chains generate charge carriers Concentration of dopant causes certain

electrons to become unpaired

Formation of polarons and bipolarons They have extended p-orbital system

Conductivity


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Conjugation: systems that have a p orbital on an atomadjacent to a double bond

Conjugate unsaturated systems - molecules with

delocalized p bonds

saturated

unsaturated

conjugated and unsaturated

Conjugation


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Electron Delocalization


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Biocompatible Polymers-Artificial nerves, Brain cells

Coatings

Sensors ammonia sensors

Polymeric Ferroelectric RAM(PFRAM)

Batteries - Polyaniline - Li

Conductive Adhesive allowing electric current to pass

through the bonds

Applications


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Reproducibility

Stability

Difficulty to process Short life span

High cost

Difficult to fabricate in labs

Drawbacks


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Monomer is inexpensive

Environmentally stable

Good processibility and conductivity Tunable properties

Polyaniline


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Quinoid(phenyl ring with 2 double bonds)

Benzenoid (phenyl ring with 3 double bonds)

[1] Terje A. Skotheim and John R. Reynolds, Conjugated Polymers:

Theory, Synthesis, Properties, and Characterization Handbook of

Conducting Polymers 3rd ed. CRC Press (2007)

Polyaniline Chemical Structure


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Leucoemeraldine Base

Pernigraniline Base

Emeraldine Base

Oxidatives States of Polyaniline[2]

[2]Sambhu Bhadra,Dipak Khastgir, Nikhil Singha and Jong

Hee Lee, Progress in preparation, processing and

applications of Polyaniline, Progress in Polymer Science

34 (2009).

Oxidatives States of Polyaniniline


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Stejskal exploited addition of Silica to the

polyaniline matrix

Discussed the mechanism of PAni growth in asubstrate

Effect of the Silica in the PAni Growth

PAni/Silia as Ammonia Sensor-Odarve, M.

Observed formation of Nanorods

Previous Works


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It is of fundamental importance to elucidate

the conduction of Pani to optimize the

potential of the Pani composites in its various

applications.

This will help determine the possible material

that will improve the conductivity of Pani.

Why study this?


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Implications

Solar cells applications

Sensor Devices

Future Directions

Controlled growth length and direction of

nanorods

Implications and Future Directions

New Friday Meeting

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