Other addition polymers are made in the same way as poly(ethene). The monomer must contain a C=C double bond. Chemists start from ethene and swap one or more hydrogen atoms for another atom or group, which gives a different monomer and a different polymer.
- Propene, CH3CH=CH2, has a methyl group (CH3) in place of one hydrogen. It makes poly(propene).
- Chloroethene, CH2=CHCl, has one chlorine atom in place of a hydrogen. It makes poly(chloroethene), better known as PVC.
- Tetrafluoroethene, CF2=CF2, has fluorine atoms in place of all four hydrogens. It makes poly(tetrafluoroethene), known as PTFE.
In each case the C=C double bond opens and the monomers join end to end with no other product. The name is poly followed by the monomer name in brackets. Each repeating unit of PTFE has four fluorine atoms, so a PTFE chain made from 100 monomer molecules contains 400 fluorine atoms.
