Digital Assignment 3: Polymers

Engineering Chemistry

Digital Assignment 3 - Polymers

Name: Prasannakumar Krishnaraj Class: SJT 504

Reg no: 15BCE0985 Semester: 2

Slot: D1 Date: 24/04/2016

Faculty: Prof. Rajagopal D.

Conducting polymers: Polyacetylene and Polyaniline - Mechanism of Conduction, doping;

Conducting polymers:

A conducting polymer is an organic based polymer that can act as a semiconductor or a conductor.

The most widely studied organic polymers are polyaniline (PANI), polypyrroles, polythiophenes, and polyphenylene vinylenes.

Conducting polymers (CPs) are extensively conjugated molecules: they have alternating single and double bonds. In these molecules, electrons are able to move from one end of the polymer to the other through the extended p-orbital system.

Hence Conducting Polymers are known to be either

Density of charge carriers.

2. Their mobility.

3. The direction.

4. Presence of doping materials (additives that facilitate the polymer conductivity)

5. Temperature.

Applications of conducting polymers:

1. As sensors into clothing.

2. Conducting polymer textiles as a camouflage for defense machinery. Since the textiles has no sharp edges they absorb more than 50% of the incident microwave radiation.

3. In LEDs.

4. In controlled drug release applications, etc.

Intrinsically Conducting Polymers

• Polymer consisting of alternating single and double bonds is called conjugated double bonds.

• In conjugation, the bonds between the carbon atoms are alternately single and double. Every bond contains a localised “sigma” (σ) bond which forms a strong chemical bond.

• In addition, every double bond also contains a less strongly localised “pi” (π) bond which is weaker.

• Conjugation of sigma and pi-electrons over the entire backbone, forms valence bands and conduction bands

Eg. Poly-acetylene and Polyaniline