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.