Polymers C11

C11.1 Addition polymerisation

Polymers are huge molecules made from many small molecules (called monomers) joined together. Different types of polymers having very different properties can be made by using different monomers.

Ethene can be used to make polyethene, which is a useful plastic as it is strong and easy to shape. It is transparent and polyethene is used in dustbins, drink bottles, and plastic carrier bags.

ethene monomers -> polyethene

Propene is another alkene and is used to make polypropene, which is a strong, tough plastic. It is used to make ropes and milk crates.

propene monomers -> polypropene

When alkenes react together, the double covalent bond between two carbon atoms opens up, and is replaced by a single carbon-carbon covalent bond between the two carbon atoms, allowing thousands of molecules to join together, end on end. This is called addition polymerisation and the polymer formed is an addition polymer. The double carbon bond in ethene makes it much more reactive than ethane.

In addition polymerisation only one product is formed.

The long chain molecules in polymers are made up of repeated patterns of atoms. This is shown by brackets.

In addition polymerisation, only one product is formed.

C11.2 Condensation polymerisation

Condensation polymerisation forms two different products -


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