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Polyenes and copolymerisation.

Polyenes

  • Polyenes are polyunsaturated organic compounds that contain atleast three alternating double and single carbon-carbon bond. For example polyacetylene, β - carotene.
    Polyenes
    Example of polyene; polyacetylene.
  • These carbon - carbon double bond undergoes an interaction known as conjugation which lead to unusual optical properties of polyenes.
  • Some polyenes are bright in colour which is unusual in hydrocarbons.
  • β-carotene is responsible for the orange colour of carrots.
  • Polyenes are more reactive than simple alkenes and they also have high electrical conductivity.
  • Dienes are related to polyenes in which there is two alternating double and single carbon-carbon bonds.

Copolymerisation

The polymers containing two or more different monomers are called  Copolymers  and  the process of formation of Copolymers is called copolymerisation. Nylon 6,6 is a copolymer.
Let A and B be two monomers. The different types of Copolymers are

1) Random (or Statistical) Copolymers:

In these polymers, the monomers are attached randomly as
Statistical Copolymers.
Random copolymer.

2) Alternating Copolymer:

Here the two monomers are arranged in an alternating manner as
Alternating Copolymers
Alternating Copolymer.

3)Block Copolymer:

Here a long sequence or block of one monomer is attached to the block of second monomer as
Block copolymer.

4)Graft Copolymer:

Here a chain of one monomer is attached to the backbone (main chain) of another monomer as
Graft Copolymer.

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