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9701 · 20.1

Addition polymerisation

Addition polymerisation is like making a long paper chain from individual rings. Small molecules with a carbon-carbon double bond (monomers) break this bond to link up into a massive chain (polymer) with no other products formed.

Need to know

What you need to know

  • The monomer must be an alkene or a substituted alkene.
  • The C=C double bond breaks, and a C-C single bond backbone forms.
  • No other molecule is produced; the empirical formula of the monomer and the repeat unit are identical.
  • The process is an 'addition' reaction on a massive scale.

Explanation

Linking Up Alkenes

  1. Addition polymer: C=C opens — repeat unit loses double bond.
  2. Monomer must contain C=C — no by-product formed.
  3. Disposal/recycling issues — non-biodegradable polyalkenes.
  4. Draw one repeat unit from displayed formula.