Difference between chain growth and step growth polymerization

Chain growth polymerisation

Step growth polymerisation

*Concentration of monomers disappears early in the reaction.

* Concentration of monomers decreases steadily throughout the reaction

*Reaction is fast and polymer is formed at once.

*The polymer is formed in gradual steps.

*There is very little change in the molecular mass throughout the reaction.

*The molecular mass of polymer increases throughout the reaction.

*Increase in reaction time increases the yield but molecular weight is affected a little.

*Long reaction time is required to get high molecular mass polymer.

*Only one repeating unit is added at a time.

Any two species present can react.

*Reaction mixture contains only a monomer, polymer and growing chain.

*All molecular species are present at any stage.