Chain propagation

Chain propagation (sometimes referred to as propagation) is a process in which a reactive intermediate is continuously regenerated during the course of a chemical chain reaction. For example in the chlorination of methane, there is a two-step propagation cycle involving as chain carriers a chlorine atom and a methyl radical

In a polymerization reaction, the reactive end-groups of a polymer chain react in each propagation step with a new monomer molecule transferring the reactive group to that last unit.