From alkene to polymer
Addition polymerisation converts many alkene or substituted-alkene monomers into one long polymer chain.
A monomer is a small molecule that joins to others during polymerisation. A polymer contains a large number of repeating units joined in a chain.
- The C=C bond of each monomer is replaced by C–C single bonding within the polymer.
- The carbon atoms from neighbouring monomers become connected by new C–C bonds.
- No second reaction product is formed.
For ethene, repeated joining of the monomer produces poly(ethene).
Substituents originally bonded to an alkene carbon stay bonded to that carbon when it becomes part of the polymer backbone.
Naming addition polymers
Name the polymer by placing poly before the name of its monomer, with the monomer name in brackets.
- ethene → poly(ethene)
- propene → poly(propene)
- chloroethene → poly(chloroethene), commonly called PVC
Exam Tip: In a polymerisation equation, include with the monomer and outside the polymer brackets. Use the monomer name when naming the polymer.