Addition Polymerisation (WJEC GCSE Chemistry)

Addition Polymers

What is addition polymerisation?

• Addition polymerisation involves small, reactive molecules called monomers reacting together to form a polymer

  • A monomer is a compound which contains a carbon-carbon double bond / C=C

• The reactivity of a monomer is due to its carbon-carbon double bond / C=C

• One of the bonds in each carbon-carbon double bond / C=C breaks open

  • This allows the molecule to join to another adjacent molecule

  • The end result is a polymer that contains only single bonds 

• Addition polymerisation of different alkene monomers forms various polymers including:

  • Polythene

  • Poly(propene)

  • Poly(vinylchloride)

  • Poly(tetrafluoroethylene) 

• To name a polymer, put the name of the monomer in brackets and add poly- as the prefix

  • The only exception to this is poly(ethene), which becomes polythene

Writing equations for addition polymerisation

• The equations used to represent the addition polymerisation of any monomer use structural formulae 

  • This is to show what happens to the bonds inside the monomer

• Addition polymerisation equations all follow a similar pattern:

  1. Draw the reactant monomer, with a lower case n in front to show that there are "some" monomers involved

  2. Draw the same molecule as a product but with a carbon-carbon single bond

  3. Add brackets around the product molecule

  4. Add one single bond to each carbon atom, continuing outside of the brackets

     • These are often called continuation bonds

  5. Add the lower case n after the brackets 

Addition polymerisation of different monomers

In all examples, the C=C bond breaks open and attaches to an adjacent molecule