Addition Polymerisation of Ethene and Other Monomers
Addition Polymerisation of Ethene and Other Monomers
Addition Polymerisation
- Addition polymerisation is a type of chemical reaction where small molecules, known as monomers, combine to form a large molecule, a polymer.
- This process involves unsaturated monomers, monomers that contain double or triple bonds.
- In the polymerisation process, these double bonds break and the monomers link together in a repeating pattern to form a polymer.
Polymerisation of Ethene
- Ethene is a common monomer used in addition polymerisation. Each ethene molecule contains a carbon-carbon double bond.
- Under high pressure and temperature, and in the presence of a catalyst, the carbon-carbon double bonds in ethene molecules break.
- The atoms of each molecule then link together to form a long chain called poly(ethene), more commonly known as polythene.
Monomers in Addition Polymerisation
- Other monomers can also undergo addition polymerisation. These include propene and tetrafluoroethene.
- Propene can form poly(propene), a versatile plastic used in a range of products, from packaging to car parts.
- Tetrafluoroethene polymerises to form poly(tetrafluoroethene), commonly known as PTFE or Teflon, which is resistant to heat and chemical reaction making it useful as a non-stick coating for pans.
Characteristics and Uses of Polymers
- Polymers have high molecular masses, making them strong and resistant to breaking, which is why they are frequently used to produce plastics and resins.
- Different types of polymers possess different characteristics. Some are hard and rigid, others are flexible and light, making the range of uses for polymers very broad.
- Despite their numerous uses, the disposal of polymers presents significant environmental challenges as they are non-biodegradable. This means they take a long time to break down, leading to pollution.
Remember - when drawing diagrams or summarising this process, always represent the monomer unit with the double bond and be aware that n represents a large number – usually thousands or millions – to indicate the length of the polymer chain.