Step Growth Polymerisation and Condensation Polymerization
"Step growth polymerisation" and condensation polymerization are two different concepts, not always identical. In fact polyurethane polymerizes with addition polymerization (because its polymerization produces no small molecules), but its reaction mechanism corresponds to a step-growth polymerization.
The distinction between "addition polymerization" and "condensation polymerization" was introduced by Wallace Hume Carothers in 1929, and refers to the type of products, respectively:
- a polymer only (addition)
- a polymer and a molecule with a low molecular weight (condensation)
The distinction between "step-growth polymerization" and "chain-growth polymerization" was introduced by Paul Flory in 1953, and refers to the reaction mechanisms, respectively:
- by functional groups (step-growth polymerization)
- by free-radical or ion (chain-growth polymerization)
Read more about this topic: Step-growth Polymerization
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