20.1.1—Addition polymerisation
- Syllabus
- 9701–2028–2029
- Objective
- 20.1.1
- Level
- AS
Addition polymerisation joins alkene monomers without eliminating a small molecule
In addition polymerisation, many alkene molecules open their C=C bonds and join into a saturated carbon-chain backbone. No small molecule is eliminated.
Draw the repeat unit by replacing the double bond with single bonds to neighbouring units, then put the repeat unit in brackets with n. The substituent on the monomer remains attached to the backbone.
nCH₂=CH₂ → [–CH₂–CH₂–]ₙ poly(ethene); nCH₂=CHCl → [–CH₂–CHCl–]ₙ PVC.
Do not leave a C=C in the repeat unit or add water as a product; those features belong to different polymerisation chemistry.
ConceptA-Level CAIE Chemistry AS