addition polymerisation

Chemsitry only

Addition polymerisation examples

You should know what addition polymerisation is and how addition polymers are formed before you read this page.

The simplest addition polymer is poly(ethene) or polythene. This is made by simply polymerising or joining lots of small ethene molecules or monomers to form the large covalent molecule poly(ethene).

polymerisation of ethene

All addition polymers are made in the same way as shown. Different polymers can be made by simply starting with different monomers e.g.

polymerisation of chloroethene to make poly(chloroethene)

By replacing one of the hydrogen atoms on ethene with a chlorine atom, a molecule called chloroethene is produced. Chloroethene is a small unsaturated molecule, similar to ethene and just like ethene it can be polymerised. To name the polymer formed produced you simply add the word poly to the name of the monomer, which must be in brackets. e.g.

polymerisation of chloroethene

Chloroethene is the modern name of the molecule shown above, traditional it was also called vinyl chloride. So its polymer would be called poly(vinyl chloride) or PVC. A polymer we are probably familiar with as it is used to make such materials as: window frames, mobile phone cases, TV frames, CDs and DVDs, guttering and drain pipes as well as waterproof coats, wellington boots and even fake leather jackets.

Poly(tetrafluoroethene) or Teflon

In the example above we replaced one of the hydrogen atoms on ethene with a chlorine atom and made a molecule called chloroethene. Instead of replacing one hydrogen with a chlorine atom replace all the hydrogen atoms in an ethene molecule with fluorine atoms. We use the prefix -fluoro to represent fluorine atoms and tetra indicates there are 4 atoms of fluorine present. The new molecule will be called tetrafluoroethene.

tetrafluoroethene

We can show the polymerisation of tetrafluoroethene to give the polymer poly(tetrafluoroethene) below. As with an addition polymerisation, the C=C bonds in the monomer are broken and the molecule simply link together:

polymerisation of tetrafluoroethene

Poly(propene)

Poly(propene) or polypropylene as it is often referred to is a widely used polymer. Its main uses are in fibres for carpets, ropes, and clothing, although it is widely used for car bumpers, milk crates and fishing nets. It is made from the monomer propene, an unsaturated alkene molecule. The structure of propene is shown below:

3D model of propene displayed formula formula condensed formula
propene propene 2d CH3CHCH2
C3H6 C3H6 C3H6

We can show the polymerisation of propene to form poly(propene) in exactly the same way as was done for the addition polymerisation of ethene, tetrafluoroethene and chloroethene:

polymerisation of propene

We can also simply use word and symbolic equations to represent the polymerisation reaction:

propene → poly(propene)
nCH3CHCH2 → (-CH3CHCH2-)n

Key Points

Practice questions

Check your understanding - Questions on addition polymerisation

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