Question

What is chain growth polymerisation and how does it take place?

Answer 1

Chain growth polymerization is the term used to describe the polymerization process in which monomer units are added one after the other to a growing chain containing a reactive intermediate (such as a free radical, a carbocation, or a carbanion).

Through a chain growth process involving specific reactive intermediates, chain growth polymerization occurs. The mechanism entails a sequential process.

1. Initiation: An initiator that can create a reactive intermediate, like a free radical (or a carbocation, or a carbanion), is necessary for chain-growth polymerization. For this, organic peroxides like benzoyl peroxide are typically used. A small quantity of initiator is provided, and it is broken down by heat, light, or an oxidation-reduction reaction to create reactive species, such as free radicals. In order to create a reactive intermediate monomer with an active center, the free radical attacked a monomer molecule.
2. Chain propagation: Now that the monomer has an active center, it attacks other monomer molecules to create dimer, trimer, and so on polymer units with active centers (free radicals).
3. Chain termination: A specific mechanism that involves the removal of the active center from the polymer chain stops its growth.