The C=C double bond in ethene is involved in the polymerisation reaction. It allows ethene molecules to join, so it is an example of an addition reaction>. Poly(ethene) is an addition polymer.

Known as a thia-Michael addition, this reaction is reversible, meaning that the resulting polythioenones (PCTE) can be depolymerized back to the starting monomer. One of the synthesized polymers ...

Addition polymers are made from molecules containing C=C bonds. Polymers have different properties and uses but it is difficult to dispose of them. DNA, starch and proteins are biological polymers.