3. Radical polymerizations

3.1 Radical chain construction

As with ionic polymerization, chain construction begins with a priming reaction, followed by numerous propagation reactions. The active center is a radical, i.e. an unpaired free electron. This is usually brought into the reaction medium by a radical initiator, whose decomposition is triggered by heating or radiation (UV, γ, X).

The very high reactivity of free radicals leads to bimolecular termination reactions between two growing macroradicals, with the result that the lifetimes of these macroradicals are very limited, to less than one second. Radical polymerization therefore lacks the character of living polymerization. This living character can be restored under certain conditions (controlled radical polymerization - CRP)...